一、安卓上手（Intent）

第一行代码的笔记

入门

Activity的基本写法：

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    //不显示标题栏，要在OnCreate之前执行
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    setContentView(R.layout.first_layout);
    //使用吐司
    Button button1 = (Button) findViewById(R.id.button_1);
    button1.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View arg0) {
            // TODO Auto-generated method stub
            Toast.makeText(FirstActivity.this, "点击啦", Toast.LENGTH_LONG).show();
        }
    });
}

AndroidManifest.xml基本写法

   <application  android:allowBackup="true" android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" >
       <activity  android:name=".FirstActivity" android:label="@string/app_name" >
           <intent-filter>
               <action android:name="android.intent.action.MAIN" />
               <category android:name="android.intent.category.LAUNCHER" />
           </intent-filter>
       </activity>

   </application>

Layout基本写法

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" >

    <Button android:id="@+id/button_1" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="Button_1" />

</LinearLayout>

使用Menu

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android" >
    <item android:id="@+id/add_item" android:title="Add" />
    <item android:id="@+id/remove_item" android:title="Remove" />
</menu>

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // TODO Auto-generated method stub
        getMenuInflater().inflate(R.menu.main, menu);
        //false无法显示
        return true;
    }

    public boolean onOptionsItemSelected(MenuItem item) {
        // TODO Auto-generated method stub
        switch(item.getItemId()){
        case R.id.add_item:
            Toast.makeText(this, "点了加", Toast.LENGTH_SHORT).show();
            break;
        case R.id.remove_item:
            Toast.makeText(this, "点了清除", Toast.LENGTH_SHORT).show();
            break;
        default:
        }
        return true;
    }
}

销毁一个活动

@Override
public void onClick(View arg0) {
    // TODO Auto-generated method stub
// Toast.makeText(FirstActivity.this, "点击啦", Toast.LENGTH_LONG).show();
    finish();
}

使用Intent

显式intent

新键一个layout:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" >
    <Button android:id="@+id/button_2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Button 2" />

</LinearLayout>

创建Activity:

public class SecondActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.second_layout);
    }

}

<activity android:name=".SecondActivity" >
</activity>   

设置点击事件：

public void onClick(View arg0) {
    // TODO Auto-generated method stub
    Intent intent = new Intent(FirstActivity.this, SecondActivity.class);
    startActivity(intent);
}

隐式intent

<activity android:name=".SecondActivity" >
    <intent-filter >
        <action android:name="com.example.activitytest.ACTION_START"/>
        <category android:name="android.intent.category.DEFAULT" />
        <category android:name="com.example.activitytest.MY_CATEGORY" />"
    </intent-filter>
</activity> 

@Override
public void onClick(View arg0) {
    // TODO Auto-generated method stub
    //intent只能指定一个action，但能指定多个category
    Intent intent = new Intent("com.example.activitytest.ACTION_START");
    intent.addCategory("com.example.activitytest.MY_CATEGORY");
    startActivity(intent);
}

更多隐式Intent

使用内置浏览器：

public void onClick(View v) {
    // TODO Auto-generated method stub
    //安卓内置动作
    Intent intent = new Intent(Intent.ACTION_VIEW);
    intent.setData(Uri.parse("http://www.baidu.com"));
    startActivity(intent);
}

Intent-filter的data标签：

android：scheme //指定协议
android:host   //指定主机名
android:port   //指定端口
android:path   //主机名和端口之后的部分
android:mimeType  //指定可以处理的数据类型

只有data中指定的内容和intent中携带的data完全一致时，当前活动才能够响应改intent

自建一个活动能响应浏览器：

<activity android:name=".ThirdActivity" >
    <intent-filter >
        <action android:name="android.intent.action.VIEW"/>
        <category android:name="android.intent.category.DEFAULT"/>
        //能响应上面的访问网站的请求
        <data android:scheme="http"/>
    </intent-filter>
</activity>

调用拨号：

public void onClick(View v) {
    // TODO Auto-generated method stub
    //拨号
    Intent intent = new Intent(Intent.ACTION_DIAL);
    intent.setData(Uri.parse("tel:100086"));
    startActivity(intent);
}

向下一个活动传递数据

String data = "哈哈";
Intent intent = new Intent(FirstActivity.this, SecondActivity.class);
intent.putExtra("info", data);
startActivity(intent);

Intent intent = getIntent();
String data = intent.getStringExtra("info");
Log.d("SecondeActivity", data);

返回数据给上一个活动

FirstActivity:

Intent intent = new Intent(FirstActivity.this, SecondActivity.class);
//第二个参数是请求码，用于回调中判断数据的来源，请求码是唯一值
startActivityForResult(intent, 1);

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    // TODO Auto-generated method stub
    switch(requestCode){
    //确定来源
    case 1:
        if(resultCode == RESULT_OK){
            String returnedData = data.getStringExtra("data_return");
            Log.d("FirstAcitivity", returnedData);
        }
        break;

    default:
    }
}

SecondActivity:

Button button2 = (Button) findViewById(R.id.button_2);
button2.setOnClickListener(new OnClickListener() {
    @Override
    public void onClick(View v) {
        // TODO Auto-generated method stub
        Intent intent = new Intent();
        intent.putExtra("data_return", "Hello First");
        //第一个参数是返回的结果
        setResult(RESULT_OK,intent);
        finish();
    }
});

如果不想按button键返回，按返回键返回则要重写：

@Override
public void onBackPressed() {
    // TODO Auto-generated method stub
    Intent intent = new Intent();
    intent.putExtra("data_return", "hello firstacitivity");
    setResult(RESULT_OK,intent);
    finish();
}