安卓小案例
UI界面
ProgressBar
增加较小进度条及进度条的隐藏
实现效果
activity_main.xml文件
MainActivity
package com.ypf.second_layout;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;
public class MainActivity extends AppCompatActivity {
private boolean flag = true;
private static final String TAG = "MainActivity";
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button button1 = findViewById(R.id.btn_1);
Button button2 = findViewById(R.id.btn_2);
Button button3 = findViewById(R.id.btn_3);
ProgressBar progressBar = findViewById(R.id.pb_1);
button1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
int progress = progressBar.getProgress();
progressBar.setProgress(progress - 10);
}
});
button2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
int progress = progressBar.getProgress();
progressBar.setProgress(progress + 10);
}
});
button3.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (flag) {
flag = false;
progressBar.setVisibility(View.INVISIBLE);
} else {
flag = true;
progressBar.setVisibility(View.VISIBLE);
}
}
});
}
}AlertDialog
效果
xml文件
java文件
package com.ypf.second_layout;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
private boolean flag = true;
private static final String TAG = "MainActivity";
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button button = findViewById(R.id.btn_1);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
AlertDialog.Builder dialog = new AlertDialog.Builder(MainActivity.this);
dialog.setTitle("title");
dialog.setMessage("message");
dialog.setIcon(R.mipmap.ic_launcher);//设置图标
dialog.setCancelable(false);//表示不能通过back返回
dialog.setPositiveButton("确定", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
Toast.makeText(MainActivity.this, "确定", Toast.LENGTH_SHORT).show();
}
});
dialog.setNegativeButton("取消", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
Toast.makeText(MainActivity.this, "取消", Toast.LENGTH_SHORT).show();
}
});
dialog.show();
}
});
}
}ProgressDialog
效果
xml文件
java文件
package com.ypf.second_layout;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import android.app.ProgressDialog;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button button = findViewById(R.id.btn_1);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
ProgressDialog dialog = new ProgressDialog(MainActivity.this);
dialog.setTitle("title");
dialog.setMessage("message");
dialog.setCancelable(true);//表示可以通过back退出
dialog.show();
// dialog.dismiss();//关闭进度对话框
}
});
}
}自定义控件
效果
title.xml
TitleLayout
package com.ypf.second_layout;
import android.content.Context;
import android.util.AttributeSet;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.Toast;
import androidx.annotation.Nullable;
public class TitleLayout extends LinearLayout {
public TitleLayout(Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
LayoutInflater.from(context).inflate(R.layout.title, this);
Button buttonBack = findViewById(R.id.btn_back);
Button buttonEdit = findViewById(R.id.btn_edit);
buttonBack.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(context, "返回键", Toast.LENGTH_SHORT).show();
}
});
buttonEdit.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(context, "编辑键", Toast.LENGTH_SHORT).show();
}
});
}
}
activity_main.xml
MainActivity
package com.ypf.second_layout;
import androidx.annotation.Nullable;
import androidx.appcompat.app.ActionBar;
import androidx.appcompat.app.AppCompatActivity;
import android.app.ProgressDialog;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button button = findViewById(R.id.btn_1);
ActionBar actionBar = getSupportActionBar();
if (actionBar != null) {
actionBar.hide();//隐藏标题栏
}
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
ProgressDialog dialog = new ProgressDialog(MainActivity.this);
dialog.setTitle("title");
dialog.setMessage("message");
dialog.setCancelable(true);//表示可以通过back退出
dialog.show();
// dialog.dismiss();//关闭进度对话框
}
});
}
}三种菜单
效果
activity_main.xml
option.xml
MainActivity
package com.ypf.itemtest;
import android.os.Bundle;
import android.util.Log;
import android.view.ActionMode;
import android.view.ContextMenu;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
import android.widget.PopupMenu;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity {
private static final String TAG = "MainActivity";
private Button ctxButton;
private Button popupButton;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ctxButton = findViewById(R.id.ctx_btn);
popupButton = findViewById(R.id.popup_btn);
//popup_btn:演示PopupMenu
popupButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//1. 实例化PopupMenu对象,参数2表示出现在谁的下方
PopupMenu popupMenu = new PopupMenu(MainActivity.this, popupButton);
//2. 加载菜单资源：利用MenuInflater将Menu资源加载到PopupMenu.getMenu()所返回的Menu对象中
//将R.menu.xxx对应的菜单资源加载到弹出式菜单中
popupMenu.getMenuInflater().inflate(R.menu.popul, popupMenu.getMenu());
//3. 为PopulMenu设置点击监听器
popupMenu.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
@Override
public boolean onMenuItemClick(MenuItem item) {
if (item.getItemId() == R.id.copy) {
Toast.makeText(MainActivity.this, "复制", Toast.LENGTH_SHORT).show();
} else if (item.getItemId() == R.id.paste) {
Toast.makeText(MainActivity.this, "粘贴", Toast.LENGTH_SHORT).show();
}
return false;
}
});
//4. 将PopupMenu显示出来
popupMenu.show();
}
});
//---------中间显示---------
//ctx_btn：演示ContextMenu
//1. 注册
// registerForContextMenu(findViewById(R.id.ctx_btn));
//2. 创建 覆盖 onCreateContextMenu 方法
//3. 菜单项操作 覆盖 onContextItemSelected 方法
//---------上方显示---------
//1. 为按钮设置上下文操作模式
//①实现ActionMode CallBack
//②在View的长按事件中去启动上下文操作模式
ActionMode.Callback callback = new ActionMode.Callback() {
@Override//创建，在启动上下文操作模式（startActionMode(CallBack))时调用
public boolean onCreateActionMode(ActionMode mode, Menu menu) {
Log.d(TAG, "onCreateActionMode: ");
getMenuInflater().inflate(R.menu.context, menu);
return true;
}
@Override//在创建方法后进行调用
public boolean onPrepareActionMode(ActionMode mode, Menu menu) {
Log.d(TAG, "onPrepareActionMode: ");
return false;
}
@Override//菜单项被点击
public boolean onActionItemClicked(ActionMode mode, MenuItem item) {
Log.d(TAG, "onActionItemClicked: ");
if (item.getItemId() == R.id.delete_context_menu) {
Toast.makeText(MainActivity.this, "delete_context_menu", Toast.LENGTH_SHORT).show();
} else if (item.getItemId() == R.id.set_context_meun) {
Toast.makeText(MainActivity.this, "set_context_meun", Toast.LENGTH_SHORT).show();
} else if (item.getItemId() == R.id.sub_operation1) {
Toast.makeText(MainActivity.this, "sub_operation1", Toast.LENGTH_SHORT).show();
} else if (item.getItemId() == R.id.sub_operation2) {
Toast.makeText(MainActivity.this, "sub_operation2", Toast.LENGTH_SHORT).show();
}
return true;
}
@Override//上下文操作模式结束时被调用
public void onDestroyActionMode(ActionMode mode) {
Log.d(TAG, "onDestroyActionMode: ");
}
};
ctxButton.setOnLongClickListener(new View.OnLongClickListener() {
@Override
public boolean onLongClick(View v) {
startActionMode(callback);
return false;
}
});
}
//创建 ContextMenu 方法
@Override
public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
if (v.getId() == R.id.ctx_btn) {
getMenuInflater().inflate(R.menu.context, menu);
}
}
// ContextMenu 选中方法
@Override
public boolean onContextItemSelected(@NonNull MenuItem item) {
if (item.getItemId() == R.id.delete_context_menu) {
Toast.makeText(this, "delete_context_menu", Toast.LENGTH_SHORT).show();
} else if (item.getItemId() == R.id.set_context_meun) {
Toast.makeText(this, "set_context_meun", Toast.LENGTH_SHORT).show();
} else if (item.getItemId() == R.id.sub_operation1) {
Toast.makeText(this, "sub_operation1", Toast.LENGTH_SHORT).show();
} else if (item.getItemId() == R.id.sub_operation2) {
Toast.makeText(this, "sub_operation2", Toast.LENGTH_SHORT).show();
}
return super.onContextItemSelected(item);
}
//创建 optionMenu 方法
@Override
public boolean onCreateOptionsMenu(Menu menu) {
//加载菜单资源
getMenuInflater().inflate(R.menu.option, menu);
return true;//将optionMenu显示出来
}
//optionMenu的选中方法
@Override
public boolean onOptionsItemSelected(@NonNull MenuItem item) {
if (item.getItemId() == R.id.save_manu) {
Toast.makeText(this, "添加菜单", Toast.LENGTH_SHORT).show();
} else if (item.getItemId() == R.id.set_manu) {
Toast.makeText(this, "设置菜单", Toast.LENGTH_SHORT).show();
} else if (item.getItemId() == R.id.sub_manu1) {
Toast.makeText(this, "sub_manu1", Toast.LENGTH_SHORT).show();
} else if (item.getItemId() == R.id.sub_manu2) {
Toast.makeText(this, "sub_manu2", Toast.LENGTH_SHORT).show();
} else if (item.getItemId() == R.id.sub_manu3) {
Toast.makeText(this, "sub_manu3", Toast.LENGTH_SHORT).show();
}
return super.onOptionsItemSelected(item);
}
}ListView
效果
activity_main.xml
MainActivity
package com.ypf.second_layout;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
private static final String TAG = "MainActivity";
private List data = new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initData();
UserAdapter userAdapter = new UserAdapter(
MainActivity.this, R.layout.user_layout, data);
ListView listView = findViewById(R.id.view_list);
listView.setAdapter(userAdapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView parent, View view, int position, long id) {
User user = data.get(position);
Toast.makeText(MainActivity.this, user.name, Toast.LENGTH_SHORT).show();
}
});
}
public void initData() {
for (int i = 0; i < 30; i++) {
User user = new User(i+"", "name" + i);
data.add(user);
}
}
}
User
package com.ypf.second_layout;
public class User {
public String id;
public String name;
public User(String id, String name) {
this.id = id;
this.name = name;
}
}
user_layout.xml
UserAdapter
package com.ypf.second_layout;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import java.util.List;
public class UserAdapter extends ArrayAdapter {
private int resourceId;
public UserAdapter(@NonNull Context context, int resource, @NonNull List objects) {
super(context, resource, objects);
this.resourceId = resource;
}
@NonNull
@Override
public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
View view;
ViewHolder viewHolder;
User user = getItem(position);
if (convertView == null) {
view = LayoutInflater.from(getContext()).inflate(resourceId, parent, false);
viewHolder = new ViewHolder();
viewHolder.user_id = view.findViewById(R.id.user_id);
viewHolder.user_name = view.findViewById(R.id.user_name);
view.setTag(viewHolder);
} else {
view = convertView;
viewHolder = (ViewHolder) view.getTag();
}
viewHolder.user_id.setText(user.id);
viewHolder.user_name.setText(user.name);
return view;
}
class ViewHolder {
TextView user_id;
TextView user_name;
}
} RecyclerView
效果：上下滑动
activity_main.xml
MainActivitypackage com.ypf.second_layout;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.os.Bundle;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.UUID;
public class MainActivity extends AppCompatActivity {
private List list = new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initData();
RecyclerView recyclerView = findViewById(R.id.recycler_view);
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(layoutManager);//设置布局管理器
UserAdapter userAdapter = new UserAdapter(list);
recyclerView.setAdapter(userAdapter);//设置适配器
}
public void initData() {
for (int i = 0; i < 30; i++) {
User user = new User(i + "", UUID.randomUUID().toString().substring(0, new Random().nextInt(30) + 5));
list.add(user);
}
}
}
user_item.xml
UserAdapter
package com.ypf.second_layout;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import java.util.List;
public class UserAdapter extends RecyclerView.Adapter {
private List list;
public UserAdapter(List list) {
this.list = list;
}
@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.user_item, parent, false);
ViewHolder viewHolder = new ViewHolder(view);
viewHolder.userName.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
int position = viewHolder.getAdapterPosition();
User user = list.get(position);
Toast.makeText(v.getContext(), user.getName(), Toast.LENGTH_SHORT).show();
}
});
viewHolder.view.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
int position = viewHolder.getAdapterPosition();
User user = list.get(position);
Toast.makeText(v.getContext(), user.toString(), Toast.LENGTH_SHORT).show();
}
});
return viewHolder;
}
@Override
public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
User user = list.get(position);
holder.userId.setText(user.getId());
holder.userName.setText(user.getName());
//也可以在这里设置点击事件,这里设置的代码后执行
// holder.userName.setOnClickListener(new View.OnClickListener() {
// @Override
// public void onClick(View v) {
// int position1 = holder.getAdapterPosition();
// User user1 = list.get(position1);
// Toast.makeText(v.getContext(), user1.getName(), Toast.LENGTH_SHORT).show();
// }
// });
// holder.view.setOnClickListener(new View.OnClickListener() {
// @Override
// public void onClick(View v) {
// int position1 = holder.getAdapterPosition();
// User user1 = list.get(position1);
// Toast.makeText(v.getContext(), user1.toString(), Toast.LENGTH_SHORT).show();
// }
// });
}
@Override
public int getItemCount() {
return list.size();
}
static class ViewHolder extends RecyclerView.ViewHolder {
TextView userId;
TextView userName;
View view;
public ViewHolder(@NonNull View itemView) {
super(itemView);
view = itemView;
userId = view.findViewById(R.id.user_id);
userName = view.findViewById(R.id.user_name);
}
}
} 效果：左右滑动
MainActivity
package com.ypf.second_layout;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.os.Bundle;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.UUID;
public class MainActivity extends AppCompatActivity {
private List list = new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initData();
RecyclerView recyclerView = findViewById(R.id.recycler_view);
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
layoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);
recyclerView.setLayoutManager(layoutManager);//设置布局管理器
UserAdapter userAdapter = new UserAdapter(list);
recyclerView.setAdapter(userAdapter);//设置适配器
}
public void initData() {
for (int i = 0; i < 30; i++) {
User user = new User(i + "", UUID.randomUUID().toString().substring(0, new Random().nextInt(10) + 5));
list.add(user);
}
}
}
效果：瀑布
MainActivity
package com.ypf.second_layout;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.RecyclerView;
import androidx.recyclerview.widget.StaggeredGridLayoutManager;
import android.os.Bundle;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;
import java.util.UUID;
public class MainActivity extends AppCompatActivity {
private List list = new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initData();
RecyclerView recyclerView = findViewById(R.id.recycler_view);
UserAdapter userAdapter = new UserAdapter(list);
recyclerView.setAdapter(userAdapter);//设置适配器
StaggeredGridLayoutManager layoutManager =
new StaggeredGridLayoutManager(3, StaggeredGridLayoutManager.VERTICAL);
recyclerView.setLayoutManager(layoutManager);
}
public void initData() {
for (int i = 0; i < 30; i++) {
User user = new User(i + "", UUID.randomUUID().toString().substring(0, new Random().nextInt(30) + 5));
list.add(user);
}
}
}
效果：QQ聊天
activity_main
MainActivity
package com.ypf.second_layout;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import java.util.ArrayList;
import java.util.List;
import java.util.UUID;
public class MainActivity extends AppCompatActivity {
private List list = new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//-----聊天内容-----
initData();
RecyclerView recyclerView = findViewById(R.id.recycler_view);
MsgAdapter msgAdapter = new MsgAdapter(list);
recyclerView.setAdapter(msgAdapter);
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(layoutManager);
//-----发送内容------
Button button = findViewById(R.id.btn);
EditText editText = findViewById(R.id.edit_text);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String context = editText.getText().toString();
if (!"".equals(context)) {
Msg msg = new Msg(context, Msg.TYPE_SEND);
list.add(msg);
//当有新消息的时候，刷新RecyclerView中的显示。其中，position中的值多少都可以
msgAdapter.notifyItemInserted(list.size() - 1);
//将RecyclerView定位到最后一行
recyclerView.scrollToPosition(list.size() - 1);
editText.setText("");
}
}
});
}
private void initData() {
for (int i = 0; i < 30; i++) {
Msg msg;
if (i % 2 == 0) {
msg = new Msg(UUID.randomUUID().toString().substring(0, 15), Msg.TYPE_RECEIVER);
} else {
msg = new Msg(UUID.randomUUID().toString().substring(0, 15), Msg.TYPE_SEND);
}
list.add(msg);
}
}
}
msg_item.xml
MsgAdapter
package com.ypf.second_layout;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import java.util.List;
public class MsgAdapter extends RecyclerView.Adapter {
private List list;
public MsgAdapter(List list) {
this.list = list;
}
@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.msg_item, parent, false);
ViewHolder viewHolder = new ViewHolder(view);
return viewHolder;
}
@Override
public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
Msg msg = list.get(position);
if (msg.getType() == Msg.TYPE_RECEIVER) {
holder.leftLinearLayout.setVisibility(LinearLayout.VISIBLE);
holder.leftMsg.setText(msg.getContent());
holder.rightLinearLayout.setVisibility(LinearLayout.GONE);
} else {
holder.leftLinearLayout.setVisibility(LinearLayout.GONE);
holder.rightLinearLayout.setVisibility(LinearLayout.VISIBLE);
holder.rightMsg.setText(msg.getContent());
}
}
@Override
public int getItemCount() {
return list.size();
}
static class ViewHolder extends RecyclerView.ViewHolder {
LinearLayout leftLinearLayout;
LinearLayout rightLinearLayout;
TextView leftMsg;
TextView rightMsg;
View msgView;
public ViewHolder(@NonNull View itemView) {
super(itemView);
msgView = itemView;
leftLinearLayout = msgView.findViewById(R.id.left_layout);
rightLinearLayout = msgView.findViewById(R.id.right_layout);
leftMsg = msgView.findViewById(R.id.left_msg);
rightMsg = msgView.findViewById(R.id.right_msg);
}
}
}
Msg
public class Msg {
public static final int TYPE_RECEIVER = 0;
public static final int TYPE_SEND = 1;
private String content;
private int type;
public Msg(String content, int type) {
this.content = content;
this.type = type;
}
}广播
接收广播
效果：动态监听网络变化
MainActivity
package com.ypf.second_layout;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.os.Bundle;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
private IntentFilter intentFilter;
private NetworkChangeReceiver networkChangeReceiver;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
intentFilter = new IntentFilter();
intentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE");
networkChangeReceiver = new NetworkChangeReceiver();
registerReceiver(networkChangeReceiver, intentFilter);
}
@Override
protected void onDestroy() {
super.onDestroy();
unregisterReceiver(networkChangeReceiver);
}
class NetworkChangeReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
Toast.makeText(context, "network changed", Toast.LENGTH_SHORT).show();
ConnectivityManager connectivityManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
if (networkInfo != null && networkInfo.isAvailable()) {//判断当前是否有网络
Toast.makeText(context, "network is Available", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(context, "network is Unavailable", Toast.LENGTH_SHORT).show();
}
}
}
}
权限
点开getActiveNetworkInfo()方法源码即可查看需要的权限
效果：静态注册实现开机启动
BootComplete
package com.ypf.second_layout;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;
public class BootComplete extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
Toast.makeText(context, "boot complete ....", Toast.LENGTH_LONG).show();
}
}AndroidManifest.xml
注：权限定义在Manifest类中，action定义在Intent类中
发送自定义广播
activity_main.xml
MainActivity
package com.ypf.second_layout;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import android.content.ComponentName;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
public class MainActivity extends AppCompatActivity {
private static final String TAG = "MainActivity";
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button button = findViewById(R.id.btn);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent("com.ypf.second_layout.MyBroadcastReceiver");
intent.setComponent(new ComponentName("com.ypf.second_layout", "com.ypf.second_layout.MyBroadcastReceiver"));
sendBroadcast(intent);
Log.d(TAG, "onClick: " + intent);
}
});
}
}
MyBroadcastReceiver
package com.ypf.second_layout;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.util.Log;
import android.widget.Toast;
public class MyBroadcastReceiver extends BroadcastReceiver {
private static final String TAG = "MyBroadcastReceiver";
@Override
public void onReceive(Context context, Intent intent) {
Toast.makeText(context, "receive in MyBroadcastReceiver", Toast.LENGTH_SHORT).show();
Log.d(TAG, "onReceive: " + intent);
}
}AndroidManifest.xml
使用本地广播
MainActivity
package com.ypf.second_layout;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.localbroadcastmanager.content.LocalBroadcastManager;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
private IntentFilter intentFilter;
private LocalReceiver localReceiver;
private LocalBroadcastManager localBroadcastManager;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
localBroadcastManager = LocalBroadcastManager.getInstance(this);//获取实例
intentFilter = new IntentFilter();
intentFilter.addAction("com.ypf.second_layout.MainActivity.LocalReceiver");
localReceiver = new LocalReceiver();
localBroadcastManager.registerReceiver(localReceiver, intentFilter);
Button button = findViewById(R.id.btn);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent("com.ypf.second_layout.MainActivity.LocalReceiver");
localBroadcastManager.sendBroadcast(intent);//发送本地广播
}
});
}
@Override
protected void onDestroy() {
super.onDestroy();
localBroadcastManager.unregisterReceiver(localReceiver);
}
class LocalReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
Toast.makeText(context, "接收本地广播", Toast.LENGTH_SHORT).show();
}
}
}
案例，账号的强制下线功能
效果
ActivityCollector
package com.ypf.second_layout;
import android.app.Activity;
import java.util.ArrayList;
import java.util.List;
public class ActivityCollector {
public static List activities = new ArrayList<>();
public static void addActivity(Activity activity) {
activities.add(activity);
}
public static void deleteActivity(Activity activity) {
activities.remove(activity);
}
public static void finishAll() {
for (Activity activity : activities) {
if (!activity.isFinishing()) {
activity.finish();
}
}
activities.clear();
}
}
BaseActivity
package com.ypf.second_layout;
import android.app.AlertDialog;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
public class BaseActivity extends AppCompatActivity {
private ForceOfflineReceiver receiver;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
ActivityCollector.addActivity(this);
}
@Override
protected void onResume() {
super.onResume();
IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction("com.ypf.second_layout.BaseActivity");
receiver = new ForceOfflineReceiver();
registerReceiver(receiver, intentFilter);
}
@Override
protected void onPause() {
super.onPause();
if (receiver != null) {
unregisterReceiver(receiver);
receiver = null;
}
}
@Override
protected void onDestroy() {
super.onDestroy();
ActivityCollector.deleteActivity(this);
}
class ForceOfflineReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
AlertDialog.Builder dialog = new AlertDialog.Builder(context);
dialog.setTitle("警告");
dialog.setMessage("你的账号已经在别处登录");
dialog.setCancelable(false);
dialog.setPositiveButton("确定", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
ActivityCollector.finishAll();
Intent intent1 = new Intent(context, LoginActivity.class);
startActivity(intent1);
}
});
dialog.show();
}
}
}
activity_login.xml
LoginActivity
package com.ypf.second_layout;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
public class LoginActivity extends BaseActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
EditText loginName = findViewById(R.id.edit_login_name);
EditText loginPassword = findViewById(R.id.edit_login_password);
Button button = findViewById(R.id.btn);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String userName = loginName.getText().toString().trim();
String password = loginPassword.getText().toString().trim();
if (userName.equals("ypf") && password.equals("123")) {
Intent intent = new Intent(LoginActivity.this, MainActivity.class);
startActivity(intent);
finish();
} else {
Toast.makeText(LoginActivity.this, "用户名或密码错误", Toast.LENGTH_SHORT).show();
}
}
});
}
}activity_main.xml
MainActivity
package com.ypf.second_layout;
import androidx.annotation.Nullable;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
public class MainActivity extends BaseActivity {
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button button = findViewById(R.id.force_offline);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent("com.ypf.second_layout.BaseActivity");
sendBroadcast(intent);
}
});
}
}
持久化
文件存储
package com.ypf.second_layout;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
public class MainActivity extends AppCompatActivity {
private EditText editText;
private Button button;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
editText = findViewById(R.id.username);
button = findViewById(R.id.login);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(MainActivity.this, SecondActivity.class);
startActivity(intent);
}
});
}
@Override
protected void onResume() {
super.onResume();
try {
String read = read();
editText.setText(read);
editText.setSelection(read.length());
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
protected void onPause() {
super.onPause();
try {
String s = editText.getText().toString();
save(s);
} catch (Exception e) {
e.printStackTrace();
}
}
public void save(String data) throws Exception {
//存储到/data/data//files/user文件中
FileOutputStream out = openFileOutput("user", MODE_PRIVATE);
BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(out));
writer.write(data);
writer.close();
}
public String read() throws Exception {
FileInputStream in = openFileInput("user");
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
StringBuilder builder = new StringBuilder();
String str = "";
while ((str = reader.readLine()) != null) {
builder.append(str);
}
reader.close();
return builder.toString();
}
}
SharedPreferences存储
package com.ypf.second_layout;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import java.util.function.Predicate;
public class MainActivity extends AppCompatActivity {
private EditText editText;
private Button button;
private SharedPreferences sharedPreferences;
private SharedPreferences.Editor editor;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
editText = findViewById(R.id.username);
button = findViewById(R.id.login);
// 存放路径： /data/data//shared_prefs/user.xml文件中
// sharedPreferences = getSharedPreferences("user", MODE_PRIVATE);
// 存放路径： /data/data//shared_prefs/MainActivity.xml文件中
// sharedPreferences = getPreferences(MODE_PRIVATE);
// 存放路径： /data/data//shared_prefs/com.ypf.second_layout_preferences.xml文件中
sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
editor = sharedPreferences.edit();
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent = new Intent(MainActivity.this, SecondActivity.class);
startActivity(intent);
}
});
}
@Override
protected void onResume() {
super.onResume();
String username = sharedPreferences.getString("username", "");
editText.setText(username);
editText.setSelection(username.length());
}
@Override
protected void onPause() {
super.onPause();
String username = editText.getText().toString();
editor.putString("username", username);
editor.apply();
}
} SQLite数据库存储
activity_main.xml
MyDatabaseHelper
package com.ypf.databaseapplication;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.widget.Toast;
import androidx.annotation.Nullable;
public class MyDatabaseHelper extends SQLiteOpenHelper {
public static final String CREATE_BOOK = "create table book(" +
"id integer primary key autoincrement," +
"author text," +
"price real," +
"pages integer," +
"name text" +
")";
public static final String CREATE_CATEGORY = "create table category(" +
"id integer primary key autoincrement," +
"name text," +
"code integer" +
")";
private Context myContext;
public MyDatabaseHelper(@Nullable Context context, @Nullable String name, @Nullable SQLiteDatabase.CursorFactory factory, int version) {
super(context, name, factory, version);
this.myContext = context;
}
//创建数据库
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_BOOK);
db.execSQL(CREATE_CATEGORY);
Toast.makeText(myContext, "数据库创建成功", Toast.LENGTH_SHORT).show();
}
//升级数据库
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("drop table if exists book");
db.execSQL("drop table if exists category");
onCreate(db);
}
}
MainActivity
package com.ypf.databaseapplication;
import androidx.appcompat.app.AppCompatActivity;
import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private static final String TAG = "MainActivity";
private Button createDatabase;
private MyDatabaseHelper dbHelper;
private Button addData;
private Button deleteData;
private Button updateData;
private Button queryData;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
dbHelper = new MyDatabaseHelper(this, "BookStore.db", null, 2);
//创建数据库
createDatabase = findViewById(R.id.create_database);
createDatabase.setOnClickListener(this::onClick);
//添加数据
addData = findViewById(R.id.add_data);
addData.setOnClickListener(this::onClick);
//删除数据
deleteData = findViewById(R.id.delete_data);
deleteData.setOnClickListener(this::onClick);
//修改数据
updateData = findViewById(R.id.update_data);
updateData.setOnClickListener(this::onClick);
//查询数据
queryData = findViewById(R.id.query_data);
queryData.setOnClickListener(this::onClick);
}
@Override
public void onClick(View v) {
if (v.getId() == R.id.create_database) {
dbHelper.getWritableDatabase();
} else if (v.getId() == R.id.add_data) {
SQLiteDatabase database = dbHelper.getWritableDatabase();
ContentValues values = new ContentValues();
//组装的第一条数据
values.put("author", "daogeli");
values.put("price", 188.8);
values.put("pages", 100);
values.put("name", "java");
database.insert("book", null, values);
values.clear();
//组装的第二条数据
values.put("author", "lisi");
values.put("price", 123.8);
values.put("pages", 58);
values.put("name", "android");
database.insert("book", null, values);
values.clear();
} else if (v.getId() == R.id.delete_data) {
SQLiteDatabase database = dbHelper.getWritableDatabase();
database.delete("book", "pages>?", new String[]{"80"});
} else if (v.getId() == R.id.update_data) {
SQLiteDatabase database = dbHelper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put("price", 10.99);
database.update("book", values, "author=?", new String[]{"lisi"});
} else if (v.getId() == R.id.query_data) {
SQLiteDatabase database = dbHelper.getWritableDatabase();
Cursor cursor = database.query("book", null, null,
null, null, null, null);
if (cursor != null) {
while (cursor.moveToNext()) {
String author = cursor.getString(cursor.getColumnIndex("author"));
double price = cursor.getDouble(cursor.getColumnIndex("price"));
int pages = cursor.getInt(cursor.getColumnIndex("pages"));
String name = cursor.getString(cursor.getColumnIndex("name"));
Log.d(TAG, "onClick: " + author);
Log.d(TAG, "onClick: " + price);
Log.d(TAG, "onClick: " + pages);
Log.d(TAG, "onClick: " + name);
}
}
}
}
}使用LitePal操作数据库
引入依赖
implementation 'org.litepal.android:core:1.4.1'app/src/main/assets/litepal.xml文件
Book
package com.ypf.second_layout;
import org.litepal.crud.DataSupport;
import lombok.Data;
@Data
public class Book extends DataSupport {
private int id;
private String name;
private double price;
private int pages;
private String author;
private String press;
}
AndroidManifest.xml
MainActivity
package com.ypf.second_layout;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import org.litepal.LitePal;
import org.litepal.crud.DataSupport;
import java.util.List;
public class MainActivity extends AppCompatActivity {
private static final String TAG = "MainActivity";
private Button makeDatabase;
private Button addData;
private Button deleteData;
private Button updateData;
private Button queryData;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//创建数据库
makeDatabase = findViewById(R.id.make_database);
makeDatabase.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
SQLiteDatabase database = LitePal.getDatabase();
Log.d(TAG, "onClick: " + database);
}
});
//增加数据
addData = findViewById(R.id.add_data);
addData.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Book book = new Book();
book.setName("java");
book.setAuthor("dageli");
book.setPages(300);
book.setPrice(260);
book.setPress("unknown");
book.save();
Log.d(TAG, "onClick: " + book);
}
});
//删除数据
deleteData = findViewById(R.id.delete_data);
deleteData.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
DataSupport.deleteAll(Book.class, "id>?", "10");
}
});
//修改数据
updateData = findViewById(R.id.update_data);
updateData.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Book book = new Book();
book.setName("java");
book.setAuthor("dageli");
book.setPages(300);
book.setPrice(100);
book.setPress("unknown");
//将列的值更新为默认值
book.setToDefault("press");
//根据id修改值
// book.update(1);
//根据条件修改值
book.updateAll("name=? and author=?", "java", "dageli");
Log.d(TAG, "onClick: " + book);
}
});
//查询数据
queryData = findViewById(R.id.query_data);
queryData.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//查询所有列数据
List books = DataSupport.findAll(Book.class);
//查询指定列的数据,也可以按条件查询
List bookList = DataSupport.select("id", "name").where("id<10").order("id desc").find(Book.class);
//按照SQL语句查询
Cursor cursor = DataSupport.findBySQL("select * from book where id=?", "1");
}
});
}
} 内容提供器
效果：打电话
AndroidManifest.xml
activity_main.xml
MainActivity
package com.ypf.second_layout;
import android.Manifest;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private Button button;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button = findViewById(R.id.call_phone);
button.setOnClickListener(this::onClick);
}
@Override
public void onClick(View v) {
if (v.getId() == R.id.call_phone) {
if (ContextCompat.checkSelfPermission(this, Manifest.permission.CALL_PHONE) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.CALL_PHONE}, 1);
} else {
call();
}
}
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
if (requestCode == 1) {
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
call();
} else {
Toast.makeText(this, "你拒绝了该权限", Toast.LENGTH_SHORT).show();
}
}
}
private void call() {
Intent intent = new Intent(Intent.ACTION_CALL);
intent.setData(Uri.parse("tel:10086"));
startActivity(intent);
}
}访问其他程序中的数据
效果：读取通讯录
常见参数
AndroidManifest.xml
activity_main.xml
activity_contact.xml
contact_item.xml
MainActivity
package com.ypf.second_layout;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private Button findContact;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//查询所有联系人
findContact = findViewById(R.id.find_contact);
findContact.setOnClickListener(this::onClick);
}
@Override
public void onClick(View v) {
if (v.getId() == R.id.find_contact) {
Intent intent = new Intent(MainActivity.this, ContactActivity.class);
startActivity(intent);
}
}
}
ContactActivity
package com.ypf.second_layout;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.Manifest;
import android.content.pm.PackageManager;
import android.database.Cursor;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.List;
public class ContactActivity extends AppCompatActivity {
private RecyclerView recyclerView;
private ContactAdapter contactAdapter;
private List contactList = new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_contact);
recyclerView = findViewById(R.id.recycler_view);
contactAdapter = new ContactAdapter(contactList);
recyclerView.setAdapter(contactAdapter);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(linearLayoutManager);
if (ContextCompat.checkSelfPermission(this, Manifest.permission.READ_CONTACTS) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.READ_CONTACTS}, 1);
} else {
readContacts();
}
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
if (requestCode == 1) {
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
readContacts();
} else {
Toast.makeText(this, "你拒绝了查看联系人权限", Toast.LENGTH_SHORT).show();
}
}
}
private void readContacts() {
Cursor cursor = null;
try {
//查询所有联系人
cursor = getContentResolver().query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI,
null, null, null, null);
if (cursor != null) {
while (cursor.moveToNext()) {
//获取联系人姓名
String contactName = cursor.getString(cursor.getColumnIndex(ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME));
//获取联系人电话
String contactPhone = cursor.getString(cursor.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));
Contact contact = new Contact(contactName, contactPhone);
contactList.add(contact);
}
contactAdapter.notifyDataSetChanged();
}
} catch (Exception e) {
e.printStackTrace();
} finally {
if (cursor != null) {
cursor.close();
}
}
}
} ContactAdapter
package com.ypf.second_layout;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import java.util.List;
public class ContactAdapter extends RecyclerView.Adapter {
private List contacts;
public ContactAdapter(List contacts) {
this.contacts = contacts;
}
@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.contact_item, parent, false);
ViewHolder viewHolder = new ViewHolder(view);
return viewHolder;
}
@Override
public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
Contact contact = contacts.get(position);
holder.contactName.setText(contact.getContactName());
holder.contactPhone.setText(contact.getContactPhone());
}
@Override
public int getItemCount() {
return contacts.size();
}
static class ViewHolder extends RecyclerView.ViewHolder {
TextView contactName;
TextView contactPhone;
View view;
public ViewHolder(@NonNull View itemView) {
super(itemView);
this.view = itemView;
contactName = view.findViewById(R.id.contact_name);
contactPhone = view.findViewById(R.id.contact_phone);
}
}
}
内容提供器
效果：增删改查
AndroidManifest.xml
activity_main.xml
MyDatabaseHelper
package com.ypf.databaseapplication;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.widget.Toast;
import androidx.annotation.Nullable;
public class MyDatabaseHelper extends SQLiteOpenHelper {
public static final String CREATE_BOOK = "create table book(" +
"id integer primary key autoincrement," +
"author text," +
"price real," +
"pages integer," +
"name text" +
")";
public static final String CREATE_CATEGORY = "create table category(" +
"id integer primary key autoincrement," +
"name text," +
"code integer" +
")";
private Context myContext;
public MyDatabaseHelper(@Nullable Context context, @Nullable String name, @Nullable SQLiteDatabase.CursorFactory factory, int version) {
super(context, name, factory, version);
this.myContext = context;
}
//创建数据库
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(CREATE_BOOK);
db.execSQL(CREATE_CATEGORY);
Toast.makeText(myContext, "数据库创建成功", Toast.LENGTH_SHORT).show();
}
//升级数据库
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("drop table if exists book");
db.execSQL("drop table if exists category");
onCreate(db);
}
}
DatabaseProvider
package com.ypf.databaseapplication;
import android.content.ContentProvider;
import android.content.ContentValues;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;
public class DatabaseProvider extends ContentProvider {
public static final int BOOK_DIR = 0;
public static final int BOOK_ITEM = 1;
public static final int CATEGORY_DIR = 2;
public static final int CATEGORY_ITEM = 3;
public static final String authority = "com.ypf.databaseapplication.provider";
private MyDatabaseHelper dbHelper;
private static UriMatcher uriMatcher;
static {
uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);
uriMatcher.addURI(authority, "book", BOOK_DIR);
uriMatcher.addURI(authority, "book/#", BOOK_ITEM);
uriMatcher.addURI(authority, "category", CATEGORY_DIR);
uriMatcher.addURI(authority, "category/#", CATEGORY_ITEM);
}
@Override
public boolean onCreate() {
dbHelper = new MyDatabaseHelper(getContext(), "BookStore.db", null, 2);
return true;//表示内容初始化器初始化成功
}
@Override
public Uri insert(Uri uri, ContentValues values) {
SQLiteDatabase database = dbHelper.getReadableDatabase();
Uri returnUri = null;
if (uriMatcher.match(uri) == BOOK_DIR || uriMatcher.match(uri) == BOOK_ITEM) {
long bookId = database.insert("book", null, values);
returnUri = Uri.parse("content://" + authority + "/book/" + bookId);
} else if (uriMatcher.match(uri) == CATEGORY_DIR || uriMatcher.match(uri) == CATEGORY_ITEM) {
long categoryId = database.insert("category", null, values);
//返回一个能表示这条新增数据的uri
returnUri = Uri.parse("content://" + authority + "/category/" + categoryId);
}
return returnUri;
}
@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
SQLiteDatabase database = dbHelper.getWritableDatabase();
int deleteRows = 0;
if (uriMatcher.match(uri) == BOOK_DIR) {
deleteRows = database.delete("book", selection, selectionArgs);
} else if (uriMatcher.match(uri) == BOOK_ITEM) {
//此方法将uri按照/进行切割，结果放到字符串列表中
String bookId = uri.getPathSegments().get(1);
deleteRows = database.delete("book", "id=?", new String[]{bookId});
} else if (uriMatcher.match(uri) == CATEGORY_DIR) {
deleteRows = database.delete("category", selection, selectionArgs);
} else if (uriMatcher.match(uri) == CATEGORY_ITEM) {
String categoryId = uri.getPathSegments().get(1);
deleteRows = database.delete("category", "id=?", new String[]{categoryId});
}
return deleteRows;
}
@Override
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
SQLiteDatabase database = dbHelper.getWritableDatabase();
int updateRows = 0;
if (uriMatcher.match(uri) == BOOK_DIR) {
updateRows = database.update("book", values, selection, selectionArgs);
} else if (uriMatcher.match(uri) == BOOK_ITEM) {
String bookId = uri.getPathSegments().get(1);
updateRows = database.update("book", values, "id=?", new String[]{bookId});
} else if (uriMatcher.match(uri) == CATEGORY_DIR) {
updateRows = database.update("category", values, selection, selectionArgs);
} else if (uriMatcher.match(uri) == CATEGORY_ITEM) {
String categoryId = uri.getPathSegments().get(1);
database.update("category", values, "id=?", new String[]{categoryId});
}
return updateRows;
}
//查询数据
@Override
public Cursor query(Uri uri, String[] projection, String selection,
String[] selectionArgs, String sortOrder) {
SQLiteDatabase database = dbHelper.getReadableDatabase();
Cursor cursor = null;
if (uriMatcher.match(uri) == BOOK_DIR) {
cursor = database.query("book", projection,
selection, selectionArgs, null, null, sortOrder);
return cursor;
} else if (uriMatcher.match(uri) == BOOK_ITEM) {
String bookId = uri.getPathSegments().get(1);
cursor = database.query("book", projection,
"id=?", new String[]{bookId}, null, null, sortOrder);
return cursor;
} else if (uriMatcher.match(uri) == CATEGORY_DIR) {
cursor = database.query("category", projection,
selection, selectionArgs, null, null, sortOrder);
return cursor;
} else if (uriMatcher.match(uri) == CATEGORY_ITEM) {
String categoryId = uri.getPathSegments().get(1);
cursor = database.query("category", projection,
"id=?", new String[]{categoryId}, null, null, sortOrder);
return cursor;
}
return null;
}
@Override
public String getType(Uri uri) {
if (uriMatcher.match(uri) == BOOK_DIR) {
return "vnd.android.cursor.dir/vnd.com.ypf.databaseapplication.provider.book";
} else if (uriMatcher.match(uri) == BOOK_ITEM) {
return "vnd.android.cursor.item/vnd.com.ypf.databaseapplication.provider.book";
} else if (uriMatcher.match(uri) == CATEGORY_DIR) {
return "vnd.android.cursor.dir/vnd.com.ypf.databaseapplication.provider.category";
} else if (uriMatcher.match(uri) == CATEGORY_ITEM) {
return "vnd.android.cursor.item/vnd.com.ypf.databaseapplication.provider.category";
}
return null;
}
}MainActivity
package com.ypf.databaseapplication;
import androidx.appcompat.app.AppCompatActivity;
import android.content.ContentValues;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private static final String TAG = "MainActivity";
private String newId;
private Button addData;
private Button deleteData;
private Button updateData;
private Button queryData;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//添加数据
addData = findViewById(R.id.add_data);
addData.setOnClickListener(this::onClick);
//删除数据
deleteData = findViewById(R.id.delete_data);
deleteData.setOnClickListener(this::onClick);
//修改数据
updateData = findViewById(R.id.update_data);
updateData.setOnClickListener(this::onClick);
//查询数据
queryData = findViewById(R.id.query_data);
queryData.setOnClickListener(this::onClick);
}
@Override
public void onClick(View v) {
if (v.getId() == R.id.add_data) {
Uri uri = Uri.parse("content://com.ypf.databaseapplication.provider/book");
ContentValues values = new ContentValues();
//组装的第一条数据
values.put("author", "daogeli");
values.put("price", 188.8);
values.put("pages", 100);
values.put("name", "java");
Uri newUri = getContentResolver().insert(uri, values);
newId = newUri.getPathSegments().get(1);
Toast.makeText(this, newUri.toString(), Toast.LENGTH_SHORT).show();
} else if (v.getId() == R.id.delete_data) {
Uri uri = Uri.parse("content://com.ypf.databaseapplication.provider/book");
getContentResolver().delete(uri, "id=?", new String[]{newId});
} else if (v.getId() == R.id.update_data) {
Uri uri = Uri.parse("content://com.ypf.databaseapplication.provider/book");
ContentValues values = new ContentValues();
values.put("author", "ypf");
values.put("price", 128.8);
values.put("pages", 56);
values.put("name", "kafka");
int updateRow = getContentResolver().update(uri, values, "id=?", new String[]{newId});
Toast.makeText(this, updateRow + "", Toast.LENGTH_SHORT).show();
} else if (v.getId() == R.id.query_data) {
Uri uri = Uri.parse("content://com.ypf.databaseapplication.provider/book");
Cursor cursor = getContentResolver().query(uri, null, null, null, null);
if (cursor != null) {
List list = new ArrayList<>();
while (cursor.moveToNext()) {
int id = cursor.getInt(cursor.getColumnIndex("id"));
String author = cursor.getString(cursor.getColumnIndex("author"));
double price = cursor.getDouble(cursor.getColumnIndex("price"));
int pages = cursor.getInt(cursor.getColumnIndex("pages"));
String name = cursor.getString(cursor.getColumnIndex("name"));
list.add(id + "-" + author + "-" + price + "-" + pages + "-" + name);
}
Log.d(TAG, "onClick: " + list);
Toast.makeText(this, list.toString(), Toast.LENGTH_SHORT).show();
}
}
}
}
运用手机多媒体
通知
AndroidManifest.xml
MainActivity
package com.ypf.second_layout;
import android.app.Notification;
import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.graphics.BitmapFactory;
import android.graphics.Color;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import androidx.annotation.Nullable;
import androidx.annotation.RequiresApi;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.NotificationCompat;
import java.io.File;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private Button button;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button = findViewById(R.id.send_notification);
button.setOnClickListener(this);
}
@RequiresApi(api = Build.VERSION_CODES.O)
@Override
public void onClick(View v) {
if (v.getId() == R.id.send_notification) {
//创建意图
Intent intent = new Intent(this, NotificationActivity.class);
PendingIntent pendingIntent = PendingIntent.getActivity(this, 1, intent, 1);
//创建NotificationChannel
NotificationChannel channel = new NotificationChannel("1", "发送通知", NotificationManager.IMPORTANCE_DEFAULT);
//创建NotificationManager
NotificationManager notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
//在NotificationManager中设置Channel
notificationManager.createNotificationChannel(channel);
//创建通知
Notification notification = new NotificationCompat.Builder(this, channel.getId())
//-----基础设置-----
.setContentTitle("title")//设置通知标题
.setContentText("text")//设置通知内容
.setWhen(System.currentTimeMillis())//设置通知时间
.setSmallIcon(R.mipmap.ic_launcher)//设置通知小图标
//设置通知大图标
.setLargeIcon(BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher_foreground))
//设置点击通知后自动取消
.setAutoCancel(true)
//设置点击通知后需要跳转的意图
.setContentIntent(pendingIntent)
//设置channel的id值
.setChannelId(channel.getId())
//-----进阶设置-----
//设置音频
.setSound(Uri.fromFile(new File("/system/media/audio/ringtones/Luna.ogg")))
//设置手机禁止和振动的时长：偶数禁止，奇数振动
.setVibrate(new long[]{0, 1000, 1000, 1000})
//设置手机IED灯。第一个参数为灯的颜色，第二个参数为灯亮起的时长，第三个参数位灯暗去的时长
.setLights(Color.GREEN, 1000, 1000)
//设置默认效果
// .setDefaults(NotificationCompat.DEFAULT_ALL)
//-----高级设置-----
//设置长文本
.setStyle(new NotificationCompat.BigTextStyle().bigText("这里显示的是全部文本"))
//显示大图片
.setStyle(new NotificationCompat.BigPictureStyle().
bigPicture(BitmapFactory.decodeResource(getResources(), R.drawable.cerfication)))
.setPriority(NotificationCompat.PRIORITY_DEFAULT)
.build();
//发送通知
notificationManager.notify(1, notification);
}
}
}NotificationActivity
package com.ypf.second_layout;
import androidx.appcompat.app.AppCompatActivity;
import android.app.NotificationManager;
import android.os.Bundle;
public class NotificationActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_notification);
NotificationManager notificationManager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
notificationManager.cancel(1);
}
}拍照片
AndroidManifest.xml
resource/xml/file_paths.xml
activity_main.xml
MainActivity
package com.ypf.databaseapplication;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.provider.MediaStore;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.content.FileProvider;
import java.io.File;
import java.io.IOException;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private ImageView picture;
private Button takePicture;
private Uri imageUri;
public static final int TAKE_PICTURE = 1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//照片
picture = findViewById(R.id.picture);
//拍照片
takePicture = findViewById(R.id.take_picture);
takePicture.setOnClickListener(this::onClick);
}
public void onClick(View v) {
if (v.getId() == R.id.take_picture) {
//创建File对象，用于存储拍照后的图片
//图片名称为output_image.jpg，存放在手机SD卡的应用关联缓存目录下
//具体路径为/sdcard/Android/data//cache
File outputImage = new File(getExternalCacheDir(), "output_image.jpg");
try {
if (outputImage.exists()) {
outputImage.delete();
}
outputImage.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
if (Build.VERSION.SDK_INT >= 24) {
//将File对象转为Uri对象
imageUri = FileProvider.getUriForFile(MainActivity.this,
"com.ypf.databaseapplication.fileprovider", outputImage);
} else {
//如果设备的系统版本低于Android7.0，则调用此方法将File对象转为Uri对象，
imageUri = Uri.fromFile(outputImage);//uri对象标识着这张图片的真实路径
}
startTakePicture();
}
}
private void startTakePicture() {
//启动相机程序
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
//指定图片的输出地址
intent.putExtra(MediaStore.EXTRA_OUTPUT, imageUri);
startActivityForResult(intent, TAKE_PICTURE);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == TAKE_PICTURE) {
if (resultCode == RESULT_OK) {
try {
//将拍摄的照片显示出来
Bitmap bitmap = BitmapFactory.decodeStream(getContentResolver().openInputStream(imageUri));
picture.setImageBitmap(bitmap);
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
}
放音乐
AndroidManifest.xml
activity_main.xml
MainActivity
package com.ypf.databaseapplication;
import android.Manifest;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.media.MediaPlayer;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import androidx.core.content.FileProvider;
import java.io.File;
import java.io.IOException;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private Button play;
private Button pause;
private Button stop;
private MediaPlayer mediaPlayer = new MediaPlayer();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
play = findViewById(R.id.play);
pause = findViewById(R.id.pause);
stop = findViewById(R.id.stop);
play.setOnClickListener(this::onClick);
pause.setOnClickListener(this::onClick);
stop.setOnClickListener(this::onClick);
if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
} else {
initMediaPlayer();
}
}
private void initMediaPlayer() {
try {
File file = new File(Environment.getExternalStorageDirectory(), "music.mp3");
mediaPlayer.setDataSource(file.getPath());
mediaPlayer.prepare();//让MediaPlayer进入到准备阶段
} catch (Exception e) {
e.printStackTrace();
}
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
if (requestCode == 1) {
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
initMediaPlayer();
} else {
Toast.makeText(this, "拒绝权限将无法使用程序", Toast.LENGTH_SHORT).show();
finish();
}
}
}
@Override
public void onClick(View v) {
if (v.getId() == R.id.play) {
if (!mediaPlayer.isPlaying()) {
mediaPlayer.start();//开始播放
}
} else if (v.getId() == R.id.pause) {
if (mediaPlayer.isPlaying()) {
mediaPlayer.pause();//暂停播放
}
} else if (v.getId() == R.id.stop) {
if (mediaPlayer.isPlaying()) {
mediaPlayer.stop();//停止播放
}
}
Toast.makeText(this, "点击成功", Toast.LENGTH_SHORT).show();
}
@Override
protected void onDestroy() {
super.onDestroy();
if (mediaPlayer != null) {
mediaPlayer.stop();
mediaPlayer.release();//释放掉与MediaPlayer对象相关的资源
}
}
}
播放视频
效果
AndroidManifest.xml
activity_main.xml
MainActivity
package com.ypf.databaseapplication;
import android.Manifest;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.media.MediaPlayer;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;
import android.widget.VideoView;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import androidx.core.content.FileProvider;
import java.io.File;
import java.io.IOException;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private Button play;
private Button pause;
private Button replay;
private VideoView videoView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
play = findViewById(R.id.play);
pause = findViewById(R.id.pause);
replay = findViewById(R.id.replay);
videoView = findViewById(R.id.video_view);
play.setOnClickListener(this::onClick);
pause.setOnClickListener(this::onClick);
replay.setOnClickListener(this::onClick);
if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
} else {
initVideoPath();
}
}
private void initVideoPath() {
File file = new File(Environment.getExternalStorageDirectory(), "00-设计模式前言.mp4");
videoView.setVideoPath(file.getPath());//指定视频文件的路径
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
if (requestCode == 1) {
if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
initVideoPath();
} else {
Toast.makeText(this, "拒绝权限将无法使用程序", Toast.LENGTH_SHORT).show();
finish();
}
}
}
@Override
public void onClick(View v) {
if (v.getId() == R.id.play) {
if (!videoView.isPlaying()) {
videoView.start();//开始播放
}
} else if (v.getId() == R.id.pause) {
if (videoView.isPlaying()) {
videoView.pause();//暂停播放
}
} else if (v.getId() == R.id.replay) {
if (videoView.isPlaying()) {
videoView.resume();//重新播放
}
}
Toast.makeText(this, "点击成功", Toast.LENGTH_SHORT).show();
}
@Override
protected void onDestroy() {
super.onDestroy();
if (videoView != null) {
videoView.suspend();//释放掉与MediaPlayer对象相关的资源
}
}
}
网络技术 WebView 发送网络请求及解析Json
效果
依赖
compile 'com.squareup.okhttp3:okhttp:3.4.1'
compile 'com.google.code.gson:gson:2.7'AndroidManifest.xml
activity_main.xml
MainActivity
package com.ypf.databaseapplication;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import com.google.gson.Gson;
import com.google.gson.reflect.TypeToken;
import org.json.JSONArray;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
public class MainActivity extends AppCompatActivity {
private static final String TAG = "MainActivity";
private String address = "http://192.168.10.161/get";
private Button sendRequest;
private TextView responseText;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
sendRequest = findViewById(R.id.send_request);
responseText = findViewById(R.id.response_text);
sendRequest.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
sendRequestWithHttpUrlConnection();
// sendRequestWithOkHttp();
}
});
}
//使用HTTPURLConnection发送网络请求
private void sendRequestWithHttpUrlConnection() {
//开启新线程发起网络请求
new Thread(new Runnable() {
@Override
public void run() {
HttpURLConnection connection = null;
BufferedReader reader = null;
try {
URL url = new URL(address);
connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
connection.setConnectTimeout(8000);
connection.setReadTimeout(8000);
InputStream in = connection.getInputStream();
reader = new BufferedReader(new InputStreamReader(in));
StringBuilder responseData = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
responseData.append(line);
}
// parseJsonWithGson(responseData.toString());
parseJsonWithJsonObject(responseData.toString());
} catch (Exception e) {
e.printStackTrace();
} finally {
if (reader != null) {
try {
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (connection != null) {
connection.disconnect();
}
}
}
}).start();
}
//使用OkHttp发起网络请求
private void sendRequestWithOkHttp() {
new Thread(new Runnable() {
@Override
public void run() {
try {
OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder()
.url(address)
.build();
Response response = client.newCall(request).execute();
String responseData = response.body().string();
parseJsonWithGson(responseData);
} catch (Exception e) {
e.printStackTrace();
}
}
}).start();
}
//使用JsonObject解析json格式
private void parseJsonWithJsonObject(String responseData) {
try {
JSONArray jsonArray = new JSONArray(responseData);
List userList = new ArrayList<>();
for (int i = 0; i < jsonArray.length(); i++) {
JSONObject jsonObject = (JSONObject) jsonArray.get(i);
int id = jsonObject.getInt("id");
String name = jsonObject.getString("name");
int age = jsonObject.getInt("age");
User user = new User(id, name, age);
userList.add(user);
Log.d(TAG, "parseJsonWithJsonObject: " + user);
}
showResponse(userList);
} catch (Exception e) {
e.printStackTrace();
}
}
//使用Gson解析JSON格式
private void parseJsonWithGson(String responseData) {
Gson gson = new Gson();
List userList = gson.fromJson(responseData, new TypeToken>() {
}.getType());
showResponse(userList);
for (User user : userList) {
Log.d(TAG, "parseJsonWithGson: " + user);
}
}
private void showResponse(List users) {
runOnUiThread(new Runnable() {
@Override
public void run() {
responseText.setText(users.toString());
}
});
}
}
实战，封装发送过程
HttpCallbackListtenner
package com.ypf.databaseapplication;
public interface HttpCallbackListtenner {
void onFinish(String response);
void onError(Exception e);
}
HttpUtil
package com.ypf.databaseapplication;
import android.view.textclassifier.TextLinks;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import okhttp3.Callback;
import okhttp3.OkHttpClient;
import okhttp3.Request;
public class HttpUtil {
public static void sendHttpRequest(String address, HttpCallbackListtenner listenner) {
new Thread(new Runnable() {
@Override
public void run() {
HttpURLConnection connection = null;
BufferedReader reader = null;
try {
URL url = new URL(address);
connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
connection.setConnectTimeout(8000);
connection.setReadTimeout(8000);
connection.setDoInput(true);
connection.setDoOutput(true);
InputStream in = connection.getInputStream();
reader = new BufferedReader(new InputStreamReader(in));
StringBuilder builder = new StringBuilder();
String line;
while ((line = reader.readLine()) != null) {
builder.append(line);
}
if (listenner != null) {
listenner.onFinish(builder.toString());
}
} catch (Exception e) {
e.printStackTrace();
listenner.onError(e);
} finally {
if (reader != null) {
try {
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (connection != null) {
connection.disconnect();
}
}
}
}).start();
}
public static void sendOkHttpRequest(String address, Callback callback) {
OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder()
.url(address)
.build();
client.newCall(request).enqueue(callback);
}
}
MainActivity
package com.ypf.databaseapplication;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import java.io.IOException;
import okhttp3.Call;
import okhttp3.Callback;
import okhttp3.Response;
public class MainActivity extends AppCompatActivity {
private static final String TAG = "MainActivity";
private Button sendRequest;
private TextView responseData;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
sendRequest = findViewById(R.id.send_request);
responseData = findViewById(R.id.response_text);
sendRequest.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
HttpUtil.sendOkHttpRequest("https://www.baidu.com", new Callback() {
@Override
public void onResponse(Call call, Response response) throws IOException {
String responseData = response.body().string();
Log.d(TAG, "onResponse: " + responseData);
}
@Override
public void onFailure(Call call, IOException e) {
Log.d(TAG, "onFailure: " + e.toString());
}
});
}
});
}
}
服务
AndroidManifest.xml
activity_main.xml
MyService
package com.ypf.databaseapplication;
import android.app.Notification;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Intent;
import android.graphics.BitmapFactory;
import android.os.Binder;
import android.os.IBinder;
import android.util.Log;
import androidx.core.app.NotificationCompat;
public class MyService extends Service {
private static final String TAG = "MyService";
private DownloadBinder mBinder = new DownloadBinder();
public MyService() {
}
class DownloadBinder extends Binder {
public void startDownload() {
Log.d(TAG, "startDownload: ");
}
public int getProgress() {
Log.d(TAG, "getProgress: ");
return 0;
}
}
@Override
public IBinder onBind(Intent intent) {
return mBinder;
}
//服务创建时调用
@Override
public void onCreate() {
super.onCreate();
Log.d(TAG, "onCreate: ");
//让服务在前台运行
Intent intent = new Intent(this, MainActivity.class);
PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, intent, 0);
Notification notification = new NotificationCompat.Builder(this)
.setContentTitle("title")
.setContentText("text")
.setSmallIcon(R.mipmap.ic_launcher)
.setLargeIcon(BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher_round))
.setContentIntent(pendingIntent)
.build();
startForeground(1, notification);
}
//服务启动时调用
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
Log.d(TAG, "onStartCommand: ");
new Thread(new Runnable() {
@Override
public void run() {
Log.d(TAG, "run: " + "处理业务逻辑");
stopSelf();
}
}).start();
return super.onStartCommand(intent, flags, startId);
}
//服务销毁时调用
@Override
public void onDestroy() {
super.onDestroy();
Log.d(TAG, "onDestroy: ");
}
}MyIntentService
package com.ypf.databaseapplication;
import android.app.IntentService;
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.util.Log;
import androidx.annotation.Nullable;
public class MyIntentService extends IntentService {
private static final String TAG = "MyIntentService";
public MyIntentService() {
super("MyIntentService");
}
//这里调用的子线程来执行的
@Override
protected void onHandleIntent(@Nullable Intent intent) {
Log.d(TAG, "onHandleIntent: " + Thread.currentThread().getId());
}
@Override
public void onDestroy() {
super.onDestroy();
Log.d(TAG, "onDestroy: " + Thread.currentThread().getId());
}
}MainActivity
package com.ypf.databaseapplication;
import android.content.ComponentName;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.support.v4.app.INotificationSideChannel;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private static final String TAG = "MainActivity";
private Button startService;
private Button stopService;
private Button bindService;
private Button unbindService;
private Button startIntentService;
private MyService.DownloadBinder downloadBinder;
private ServiceConnection serviceConnection = new ServiceConnection() {
//活动与服务成功绑定之后调用
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
downloadBinder = (MyService.DownloadBinder) service;
downloadBinder.startDownload();
downloadBinder.getProgress();
}
//活动与服务断开的时候调用
@Override
public void onServiceDisconnected(ComponentName name) {
}
};
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
startService = findViewById(R.id.start_service);
stopService = findViewById(R.id.stop_service);
startService.setOnClickListener(this::onClick);
stopService.setOnClickListener(this::onClick);
bindService = findViewById(R.id.bind_service);
unbindService = findViewById(R.id.unbind_service);
bindService.setOnClickListener(this::onClick);
unbindService.setOnClickListener(this::onClick);
startIntentService = findViewById(R.id.start_intent_service);
startIntentService.setOnClickListener(this::onClick);
}
@Override
public void onClick(View v) {
if (v.getId() == R.id.start_service) {
Intent intent = new Intent(this, MyService.class);
startService(intent);
} else if (v.getId() == R.id.stop_service) {
Intent intent = new Intent(this, MyService.class);
stopService(intent);
} else if (v.getId() == R.id.bind_service) {
Intent intent = new Intent(this, MyService.class);
bindService(intent, serviceConnection, BIND_AUTO_CREATE);
} else if (v.getId() == R.id.unbind_service) {
Intent intent = new Intent(this, MyService.class);
unbindService(serviceConnection);
} else if (v.getId() == R.id.start_intent_service) {
Log.d(TAG, "onClick: " + Thread.currentThread().getId());
Intent intent = new Intent(this, MyIntentService.class);
startService(intent);
}
}
}
完整的文件下载
效果
AndroidManifest.xml
activity_main.xml
DownloadListener
package com.ypf.myapplication;
public interface DownloadListener {
//用于通知当前的下载进度
void onProgress(int progress);
//用于通知下载成功事件
void onSuccess();
//用于通知下载失败事件
void onFailed();
//用于通知下载暂停事件
void onPaused();
//用于通知下载取消事件
void onCanceled();
}
DownloadTask
package com.ypf.myapplication;
import android.os.AsyncTask;
import android.os.Environment;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.RandomAccessFile;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;
/**
* 第一个参数：表示在执行DownloadTask的时候需要传入一个String参数给后台任务
* 第二个参数：表示使用Integer参数表示进度显示单位
* 第三个参数：表示使用Integer参数来反馈执行的结果
*/
public class DownloadTask extends AsyncTask {
public static final int TYPE_SUCCESS = 0;
public static final int TYPE_FAILED = 1;
public static final int TYPE_PAUSED = 2;
public static final int TYPE_CANCELED = 3;
private DownloadListener downloadListener;//下载状态通过这个参数来回调
private boolean isPaused = false;
private boolean isCanceled = false;
private int lastProgress;
public DownloadTask(DownloadListener downloadListener) {
this.downloadListener = downloadListener;
}
//后台执行下载逻辑
@Override
protected Integer doInBackground(String... params) {
InputStream is = null;
File file = null;
RandomAccessFile randomAccessFile = null;
try {
String downloadUrl = params[0];//从参数中获取下载URL地址
long downloadedLength = 0;
String fileName = downloadUrl.substring(downloadUrl.lastIndexOf("/"));//根据URL地址解析出文件名称
String directory = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).getPath();
file = new File(directory + fileName);
if (file.exists()) {
downloadedLength = file.length();//读取已下载的文件字节数
}
long contentLength = getContentLength(downloadUrl);
if (contentLength == 0) {
return TYPE_FAILED;
} else if (contentLength == downloadedLength) {
return TYPE_SUCCESS;
}
OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder()
//告诉服务器要从哪个字节开始下载
.addHeader("RANGE", "bytes=" + downloadedLength + "-")
.url(downloadUrl)
.build();
Response response = client.newCall(request).execute();
if (response != null) {
is = response.body().byteStream();
randomAccessFile = new RandomAccessFile(file, "rw");
randomAccessFile.seek(downloadedLength);
byte[] b = new byte[1024];
int total = 0;
int len = 0;
while ((len = is.read(b)) != -1) {
if (isPaused) {
return TYPE_PAUSED;
} else if (isCanceled) {
return TYPE_CANCELED;
} else {
total += len;
randomAccessFile.write(b, 0, len);
int progress = (int) ((total + downloadedLength) * 100 / contentLength);
publishProgress(progress);
}
}
response.close();
return TYPE_SUCCESS;
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if (is != null) {
is.close();
}
if (randomAccessFile != null) {
randomAccessFile.close();
}
if (isCanceled && file != null) {
file.delete();
}
} catch (Exception e) {
e.printStackTrace();
}
}
return TYPE_FAILED;
}
//在界面上更新当前下载进度
@Override
protected void onProgressUpdate(Integer... values) {
int progress = values[0];
if (progress > lastProgress) {
downloadListener.onProgress(progress);
lastProgress = progress;
}
}
//通知最终的下载结果
@Override//根据传入的下载状态进行回调
protected void onPostExecute(Integer status) {
if (status == TYPE_SUCCESS) {
downloadListener.onSuccess();
} else if (status == TYPE_FAILED) {
downloadListener.onFailed();
} else if (status == TYPE_PAUSED) {
downloadListener.onPaused();
} else if (status == TYPE_CANCELED) {
downloadListener.onCanceled();
}
}
//获取需要下载的文件总长度
private long getContentLength(String downloadUrl) throws IOException {
OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder()
.url(downloadUrl)
.build();
Response response = client.newCall(request).execute();
if (response != null && response.isSuccessful()) {
long contentLength = response.body().contentLength();
response.body().close();
return contentLength;
}
return 0;
}
public void pauseDownload() {
isPaused = true;
}
public void cancelDownload() {
isCanceled = true;
}
}
DownloadService
package com.ypf.myapplication;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Intent;
import android.graphics.BitmapFactory;
import android.os.Binder;
import android.os.Environment;
import android.os.IBinder;
import android.widget.Toast;
import androidx.core.app.NotificationCompat;
import java.io.File;
public class DownloadService extends Service {
private DownloadTask downloadTask;
private String downloadUrl;
private DownloadListener downloadListener = new DownloadListener() {
@Override
public void onProgress(int progress) {
getNotificationManager().notify(1, getNotification("Downloading...", progress));
}
@Override
public void onSuccess() {
downloadTask = null;
//下载成功时前台服务通知关闭
stopForeground(true);
//创建一个下载成功的通知
getNotificationManager().notify(1, getNotification("Download Success", -1));
Toast.makeText(DownloadService.this, "Download Success", Toast.LENGTH_SHORT).show();
}
@Override
public void onFailed() {
downloadTask = null;
//下载失败时前台服务关闭
stopForeground(true);
//并关键一个下载失败的通知
getNotificationManager().notify(1, getNotification("Download Failed", -1));
Toast.makeText(DownloadService.this, "Download Failed", Toast.LENGTH_SHORT).show();
}
@Override
public void onPaused() {
downloadTask = null;
Toast.makeText(DownloadService.this, "Paused", Toast.LENGTH_SHORT).show();
}
@Override
public void onCanceled() {
downloadTask = null;
stopForeground(true);
Toast.makeText(DownloadService.this, "Canceled", Toast.LENGTH_SHORT).show();
}
};
public DownloadService() {
}
private DownloadBinder mBinder = new DownloadBinder();
@Override
public IBinder onBind(Intent intent) {
return mBinder;
}
class DownloadBinder extends Binder {
public void startDownload(String url) {
if (downloadTask == null) {
downloadUrl = url;
downloadTask = new DownloadTask(downloadListener);
downloadTask.execute(downloadUrl);
startForeground(1, getNotification("Downloading", 0));
Toast.makeText(DownloadService.this, "Downloading", Toast.LENGTH_SHORT).show();
}
}
public void pauseDownload() {
if (downloadTask != null) {
downloadTask.pauseDownload();
}
}
public void cancelDownload() {
if (downloadTask != null) {
downloadTask.cancelDownload();
}
if (downloadUrl != null) {
//取消下载时需要将文件删除，并将通知关闭
String fileName = downloadUrl.substring(downloadUrl.lastIndexOf("/"));
String directory = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).getPath();
File file = new File(directory + fileName);
if (file.exists()) {
file.delete();
}
getNotificationManager().cancel(1);
stopForeground(true);
Toast.makeText(DownloadService.this, "Canceled", Toast.LENGTH_SHORT).show();
}
}
}
private NotificationManager getNotificationManager() {
return (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
}
private Notification getNotification(String title, int progress) {
Intent intent = new Intent(this, MainActivity.class);
PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, intent, 0);
NotificationCompat.Builder builder = new NotificationCompat.Builder(this);
builder.setContentTitle(title);
builder.setSmallIcon(R.mipmap.ic_launcher);
builder.setLargeIcon(BitmapFactory.decodeResource(getResources(), R.mipmap.ic_launcher));
builder.setContentIntent(pendingIntent);
if (progress >= 0) {
//当progress>=0时，显示进度条
builder.setContentText(progress + "%");
builder.setProgress(100, progress, false);
}
return builder.build();
}
}MainActivity
package com.ypf.myapplication;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import android.Manifest;
import android.content.ComponentName;
import android.content.Intent;
import android.content.ServiceConnection;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.os.IBinder;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private Button startDownload;
private Button pauseDownload;
private Button cancelDownload;
private DownloadService.DownloadBinder downloadBinder;
private ServiceConnection connection = new ServiceConnection() {
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
downloadBinder = (DownloadService.DownloadBinder) service;
}
@Override
public void onServiceDisconnected(ComponentName name) {
}
};
private String[] permissions = new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE};
private boolean checkPermissions() {
for (String permission : permissions) {
if (ContextCompat.checkSelfPermission(this, permission) != PackageManager.PERMISSION_GRANTED) {
return false;
}
}
return true;
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
startDownload = findViewById(R.id.start_download);
pauseDownload = findViewById(R.id.pause_download);
cancelDownload = findViewById(R.id.cancel_download);
startDownload.setOnClickListener(this::onClick);
pauseDownload.setOnClickListener(this::onClick);
cancelDownload.setOnClickListener(this::onClick);
Intent intent = new Intent(this, DownloadService.class);
startService(intent);//启动服务
bindService(intent, connection, BIND_AUTO_CREATE);//绑定服务
if (!checkPermissions()) {
ActivityCompat.requestPermissions(this, permissions, 1);
}
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
if (requestCode == 1) {
if (grantResults.length > 0 && grantResults[0] != PackageManager.PERMISSION_GRANTED) {
Toast.makeText(this, "拒绝权限将无法使用程序", Toast.LENGTH_SHORT).show();
finish();
}
}
}
@Override
public void onClick(View v) {
if (v.getId() == R.id.start_download) {
String url = "https://download.jetbrains.com.cn/idea/ideaIU-2021.1.exe";
downloadBinder.startDownload(url);
} else if (v.getId() == R.id.pause_download) {
downloadBinder.pauseDownload();
} else if (v.getId() == R.id.cancel_download) {
downloadBinder.cancelDownload();
}
}
@Override
protected void onDestroy() {
super.onDestroy();
unbindService(connection);
}
}效果，前台下载简单实现
activity_download.xml
DownloadActivity
package com.ypf.myexample;
import androidx.appcompat.app.AppCompatActivity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Environment;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;
import android.widget.TextView;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.nio.channels.AsynchronousChannelGroup;
/**
* 下载文件
* 1. 网络上请求数据：申请网络权限，读写存储权限
* 2. 布局我们的Layout
* 3. 下载前 UI
* 4. 下载中 数据，更新进度
* 5. 下载后 UI
*/
public class DownloadActivity extends AppCompatActivity implements View.OnClickListener {
private static final int INIT_PROGRESS = 0;
public static final String APK_URL = "https://download.jetbrains.com.cn/idea/ideaIU-2021.1.exe";
private ProgressBar progressBar;
private Button button;
private TextView textView;
String filePath;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_download);
//初始化视图，点击监听
initView();
//初始化UI数据
setData();
}
private void initView() {
progressBar = findViewById(R.id.download_progress_bar);
button = findViewById(R.id.download_button);
textView = findViewById(R.id.download_text_view);
button.setOnClickListener(this::onClick);
}
@Override
public void onClick(View v) {
if (v.getId() == R.id.download_button) {
// TODO: 2021/5/1 下载任务
DownloadAsyncTask task = new DownloadAsyncTask();
task.execute(APK_URL);
}
}
private void setData() {
progressBar.setProgress(INIT_PROGRESS);
button.setText(R.string.click_download);
textView.setText(R.string.download_text);
}
public class DownloadAsyncTask extends AsyncTask {
@Override//异步任务之前，在主线程中
protected void onPreExecute() {
//可以操作UI
button.setText(R.string.downloading);
textView.setText(R.string.downloading);
progressBar.setProgress(INIT_PROGRESS);
}
@Override//在另外一个事件中处理事件
protected Boolean doInBackground(String... strings) {
if (strings == null || strings.length < 1) {
return false;
}
try {
//构造URL
URL url = new URL(strings[0]);
//构造connection
URLConnection connection = url.openConnection();
//获取输入流
InputStream inputStream = connection.getInputStream();
//获取下载内容的总长度
int contentLength = connection.getContentLength();
//已下载的大小
int downloadSize = 0;
//准备下载地址
String fileName = url.getPath().substring(url.getPath().lastIndexOf("/") + 1);
filePath = Environment.getExternalStorageDirectory() + File.separator + fileName;
File file = new File(filePath);
if (file.exists()) {
boolean b = file.delete();
if (!b) {//表示删除失败
return false;
}
}
byte[] bytes = new byte[1024];
int len;
//创建一个输出管道
OutputStream outputStream = new FileOutputStream(file);
while ((len = inputStream.read(bytes)) != -1) {
//将下载的文件放到文件管道里
outputStream.write(bytes, 0, len);
//累加大小
downloadSize += len;
//发送进度
publishProgress(downloadSize * 100 / contentLength);
}
outputStream.close();
inputStream.close();
} catch (Exception e) {
e.printStackTrace();
return false;
}
return true;
}
@Override
protected void onProgressUpdate(Integer... values) {
super.onProgressUpdate();
if (values != null && values.length > 0) {
progressBar.setProgress(values[0]);
}
}
@Override//异步任务之后，在主线程中 处理结果
protected void onPostExecute(Boolean result) {
//处理结果
button.setText(result ? getString(R.string.download_finish) : getString(R.string.download_failed));
textView.setText(result ? getString(R.string.download_finish) + filePath : getString(R.string.download_failed));
}
}
}