AsyncTask 异步

MainActivity

public class MainActivity extends AppCompatActivity {

private String mUrl = "https://suggest.taobao.com/sug?code=utf-8&q=%E6%89%8B%E6%9C%BA";
private ListView lv;
private List<List<String>> mList = new ArrayList<>();
private MyAdapter adapter;
private ContentResolver resolver;
private Uri uri;
private int i;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    initView();

    adapter = new MyAdapter(MainActivity.this, mList);
    lv.setAdapter(adapter);


    resolver = getContentResolver();
    uri = Uri.parse("content://com.bawei.diyizhoumoni1.provider.provider.MyProvider/user");


    //判断有网没网
    if(isNetworkConnected(MainActivity.this)){
        Cursor cursor = resolver.query(uri, null, null, null, null);
        if(cursor.getCount()==0){
            new MyTask().execute(mUrl);
            Toast.makeText(MainActivity.this,"请求数据",Toast.LENGTH_SHORT).show();
        }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 neirong = query.getString(query.getColumnIndex("neirong"));
                mList.add(Collections.singletonList(neirong));
            }
            adapter.setList(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 neirong = cursorw.getString(cursorw.getColumnIndex("neirong"));
                mList.add(Collections.singletonList(neirong));
            }
            adapter.setList(mList);
        }
    }

	//条目长点击事件
    lv.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
        @Override
        public boolean onItemLongClick(AdapterView<?> parent, View view, final int position, long id) {
            AlertDialog.Builder builder=new AlertDialog.Builder(MainActivity.this);
            builder.setTitle("这是标题");
            builder.setMessage("确认要删除吗？");
            builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                        resolver.delete(uri, "neirong=?", new String[]{mList.get(position).toString()});
                        Toast.makeText(MainActivity.this,"删除成功",Toast.LENGTH_SHORT).show();
                        mList.remove(position);
                        adapter.notifyDataSetChanged();




                }
            });
            builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {

                }
            });
            AlertDialog d = builder.create();
            d.show();
            return false;
        }
    });

}


private void initView() {
    lv = findViewById(R.id.Show_lv);
}

class MyTask extends AsyncTask<String, View, List<List<String>>> {

    @Override
    protected List<List<String>> doInBackground(String... strings) {
        try {
            URL url = new URL(strings[0]);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            if (connection.getResponseCode() == 200) {
                InputStream stream = connection.getInputStream();
                String getstr = getstr(stream);
                Gson gson = new Gson();
                MyData myData = gson.fromJson(getstr, MyData.class);
              //  Log.d("aaa",myData.toString());
                mList=myData.getResult();
                for (int i=0;i<mList.size();i++){
                    ContentValues values=new ContentValues();
                    values.put("neirong",mList.get(i).toString());
                    resolver.insert(uri,values);
                }
                return mList;
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }

    @Override
    protected void onPostExecute(List<List<String>> lists) {
        super.onPostExecute(lists);
        adapter.setList((List<List<String>>) lists);
    }
}

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;
}
//转换
private String getstr(InputStream stream) throws IOException {
    BufferedReader bf = new BufferedReader(new InputStreamReader(stream));
    StringBuffer buffer = new StringBuffer();
    String con = null;
    while ((con = bf.readLine()) != null) {
        buffer.append(con);
    }
    return buffer.toString();
}

}

//适配器
package com.bawei.diyizhoumoni1.adapter;

import android.content.Context;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

import com.bawei.diyizhoumoni1.R;

import java.util.List;

public class MyAdapter extends BaseAdapter {
private Context mContext;
private List<List> mList;

public MyAdapter(Context mContext, List<List<String>> mList) {
    this.mContext = mContext;
    this.mList = mList;
}

public void setList (List<List<String>> list){
    this.mList=list;
    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(mContext, R.layout.list_item,null);
        holder=new ViewHolder();
        holder.tv=convertView.findViewById(R.id.Text_tv);
        convertView.setTag(holder);
    }else{
        holder=(ViewHolder)convertView.getTag();
    }
    holder.tv.setText(mList.get(position).toString());

    return convertView;
}
class ViewHolder{
    TextView tv;
}

}

//数据库
package com.bawei.diyizhoumoni1.helper;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class MyHelper extends SQLiteOpenHelper {
public MyHelper(Context context) {
super(context, “BBB”, null, 1);
}

@Override
public void onCreate(SQLiteDatabase db) {

    String sql="create table if not exists user(uid integer primary key autoincrement,neirong text)";
    db.execSQL(sql);
}

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

}

}

//增删该查
package com.bawei.diyizhoumoni1.provider;

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;

import com.bawei.diyizhoumoni1.helper.MyHelper;

public class MyProvider extends ContentProvider {

private int i;
private static UriMatcher um=new UriMatcher(UriMatcher.NO_MATCH);
static {
    um.addURI("com.bawei.diyizhoumoni1.provider.provider.MyProvider","user",100);
}
private SQLiteDatabase db;

@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) {
    switch (um.match(uri)){
        case 100:
            db.insert("user",null,values);
            break;
    }
    return null;
}

@Override
public int delete(Uri uri, String selection, String[] selectionArgs) {
    switch (um.match(uri)){
        case 100:
            i = db.delete("user", selection, selectionArgs);

            break;
    }
    return i;
}

@Override
public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
    return 0;
}

}

//清单文件

<?xml version="1.0" encoding="utf-8"?>

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <provider
        android:authorities="com.bawei.diyizhoumoni1.provider.provider.MyProvider"
        android:name="com.bawei.diyizhoumoni1.provider.MyProvider"
        android:exported="true"></provider>
</application>

仅供参考！！！