一个列表展示

main

package com.example.zhoukao_01_mn;

import android.app.AlertDialog;

import android.app.Dialog;

import android.content.ContentResolver;

import android.content.ContentValues;

import android.content.Context;

import android.content.DialogInterface;

import android.database.Cursor;

import android.net.ConnectivityManager;

import android.net.NetworkInfo;

import android.net.Uri;

import android.os.AsyncTask;

import android.os.Bundle;

import android.support.v7.app.AppCompatActivity;

import android.util.Log;

import android.view.View;

import android.widget.AdapterView;

import android.widget.ListView;

import android.widget.Toast;

import com.example.zhoukao_01_mn.adapter.MyAdapter;

import com.example.zhoukao_01_mn.bean.MyData;

import com.google.gson.Gson;

import java.io.BufferedReader;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.net.HttpURLConnection;

import java.net.MalformedURLException;

import java.net.URL;

import java.util.ArrayList;

import java.util.Collections;

import java.util.List;

public class MainActivityextends AppCompatActivity {

private ListViewlv;

private StringmUrl="https://suggest.taobao.com/sug?code=utf-8&q=%E6%89%8B%E6%9C%BA";

private MyAdaptermyAdapter;

private ContentResolverresolver;

private Uriuri = Uri.parse("content://com.example.zhoukao_01_mn.provider.provider.MyContentprovider/user");

private List>mList =new ArrayList<>();

@Override

    protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

initView();

resolver = getContentResolver();

myAdapter =new MyAdapter(MainActivity.this,mList);

lv.setAdapter(myAdapter);

if(isNetworkConnected(MainActivity.this)){

Cursor cursor =resolver.query(uri,null,null,null,null);

if(cursor.getCount()==0){

new MyToack().execute(mUrl);

}else{

Toast.makeText(MainActivity.this,"有网，已经请求过数据并且保存到了数据库",Toast.LENGTH_SHORT).show();

Cursor query =resolver.query(uri,null,null,null,null);

while (query.moveToNext()){

String string = query.getString(query.getColumnIndex("string"));

mList.add(Collections.singletonList(string));

}

myAdapter.setmList(mList);

}

}else{

Toast.makeText(MainActivity.this,"没有联网,从数据库请求数据",Toast.LENGTH_SHORT).show();

Cursor cursorw =resolver.query(uri,null,null,null,null);

if(cursorw.getCount()==0){

Toast.makeText(MainActivity.this,"数据库没有数据",Toast.LENGTH_SHORT).show();

}else {

while (cursorw.moveToNext()) {

String string = cursorw.getString(cursorw.getColumnIndex("string"));

mList.add(Collections.singletonList(string));

}

//                Log.d("zzz",mList.toString());

                myAdapter.setmList(mList);

}

}

lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {

@Override

            public void onItemClick(AdapterView parent, View view,final int position,long id) {

AlertDialog.Builder builder =new AlertDialog.Builder(MainActivity.this);

builder.setTitle("确认删除吗？");

builder.setNegativeButton("取消",new DialogInterface.OnClickListener() {

@Override

                    public void onClick(DialogInterface dialog,int which) {

}

});

builder.setPositiveButton("确认",new DialogInterface.OnClickListener() {

@Override

                    public void onClick(DialogInterface dialog,int which) {

//                        Toast.makeText(MainActivity.this,mList.get(position).toString()+"",Toast.LENGTH_SHORT).show();

                        resolver.delete(uri,"string=?",new String[]{mList.get(position).toString()});

Toast.makeText(MainActivity.this,"删除成功！",Toast.LENGTH_SHORT).show();

mList.remove(position);

myAdapter.notifyDataSetChanged();

}

});

builder.show();

}

});

}

public boolean isNetworkConnected(Context context) {

if (context !=null) {

ConnectivityManager mConnectivityManager = (ConnectivityManager) context

.getSystemService(Context.CONNECTIVITY_SERVICE);

NetworkInfo mNetworkInfo = mConnectivityManager.getActiveNetworkInfo();

if (mNetworkInfo !=null) {

return mNetworkInfo.isAvailable();

}

}

return false;

}

private void initView() {

lv = (ListView) findViewById(R.id.lv);

}

class MyToackextends AsyncTask>>{

@Override

        protected List> doInBackground(String... strings) {

try {

URL url =new URL(strings[0]);

HttpURLConnection connection = (HttpURLConnection) url.openConnection();

if(connection.getResponseCode()==200){

InputStream stream = connection.getInputStream();

Gson gson =new Gson();

MyData myData = gson.fromJson(new BufferedReader(new InputStreamReader(stream)), MyData.class);

mList=myData.getResult();

for(int i=0;i

ContentValues values =new ContentValues();

Log.d("zzz",mList.get(i).toString());

values.put("string",mList.get(i).toString());

resolver.insert(uri,values);

}

return mList;

}

}catch (Exception e) {

e.printStackTrace();

}

return null;

}

@Override

        protected void onPostExecute(List> lists) {

super.onPostExecute(lists);

myAdapter.setmList(lists);

}

}

}

内容提供者

package com.example.zhoukao_01_mn.provider;

import android.content.ContentProvider;

import android.content.ContentValues;

import android.content.Context;

import android.content.UriMatcher;

import android.database.Cursor;

import android.database.sqlite.SQLiteDatabase;

import android.net.Uri;

import com.example.zhoukao_01_mn.Helper.MyHelper;

import com.example.zhoukao_01_mn.MainActivity;

public class MyContentproviderextends ContentProvider {

private  SQLiteDatabasedb;

private static UriMatcherum =new UriMatcher(UriMatcher.NO_MATCH);

static {

um.addURI(".provider.provider.MyContentprovider","user",100);

}

@Override

    public boolean onCreate() {

MyHelper helper =new MyHelper(getContext());

db = helper.getWritableDatabase();

return false;

}

@Override

    public Cursor query( Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {

Cursor cursor =db.query("user",null,null,null,null,null,null);

return cursor;

}

@Override

    public String getType( Uri uri) {

return null;

}

@Override

    public Uri insert(Uri uri,  ContentValues values) {

db.insert("user",null,values);

return null;

}

@Override

    public int delete( Uri uri,  String selection, String[] selectionArgs) {

int i =db.delete("user", selection, selectionArgs);

return i;

}

@Override

    public int update( Uri uri,  ContentValues values,  String selection,String[] selectionArgs) {

return 0;

}

}

helper

package com.example.zhoukao_01_mn.Helper;

import android.content.Context;

import android.database.sqlite.SQLiteDatabase;

import android.database.sqlite.SQLiteOpenHelper;

public class MyHelperextends SQLiteOpenHelper {

public MyHelper(Context context) {

super(context,"show",null,1);

}

@Override

    public void onCreate(SQLiteDatabase db) {

String sql ="create table if not exists user(string text)";

db.execSQL(sql);

}

@Override

    public void onUpgrade(SQLiteDatabase db,int oldVersion,int newVersion) {

}

}

adapter

package com.example.zhoukao_01_mn.adapter;

import android.content.Context;

import android.util.Log;

import android.view.View;

import android.view.ViewGroup;

import android.widget.BaseAdapter;

import android.widget.TextView;

import com.example.zhoukao_01_mn.R;

import java.util.List;

public class MyAdapterextends BaseAdapter {

private Contextcontext;

private List>mList;

public MyAdapter(Context context, List> mList) {

this.context = context;

this.mList = mList;

}

public void setmList(List> mList){

this.mList=mList;

notifyDataSetChanged();

}

@Override

    public int getCount() {

return mList.size();

}

@Override

    public Object getItem(int position) {

return null;

}

@Override

    public long getItemId(int position) {

return 0;

}

@Override

    public View getView(int position, View convertView, ViewGroup parent) {

ViewHolder holder;

if(convertView ==null){

convertView=View.inflate(context, R.layout.list_item,null);

holder =new ViewHolder();

holder.tv=convertView.findViewById(R.id.tv);

convertView.setTag(holder);

}else{

holder = (ViewHolder) convertView.getTag();

}

holder.tv.setText(mList.get(position).toString());

return convertView;

}

class ViewHolder{

TextViewtv;

}

}