自定义ContentProvider

1.继承ContentProvider

package com.fsg.thinkpad.application;

import android.content.ContentProvider;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;

/**
* Created by ThinkPad on 2016/2/28.
*/
public class MyProvider extends ContentProvider {
public static final Uri URI=Uri.parse("content://com.fsg.thinkpad.application");
SQLiteDatabase sqLiteDatabase;
@Override
public boolean onCreate() {
sqLiteDatabase=getContext().openOrCreateDatabase("mycp.db", Context.MODE_PRIVATE,null);
sqLiteDatabase.execSQL("create table if not exists tab(" +
"_id integer primary key autoincrement," +
"name text);");
return true;
}

@Override
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) {
Cursor cursor=sqLiteDatabase.query("tab",null,null,null,null,null,null);
return cursor;
}

@Override
public String getType(Uri uri) {
return null;
}

@Override
public Uri insert(Uri uri, ContentValues values) {
sqLiteDatabase.insert("tab",null,values);
return null;
}

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

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

2.主界面

package com.fsg.thinkpad.application;

import android.content.ContentValues;
import android.database.Cursor;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;

public class MainActivity extends AppCompatActivity {

private static final String TAG = "MainActivity";

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

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();

//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}

return super.onOptionsItemSelected(item);
}

public void onClickWriteDB(View view){
ContentValues values=new ContentValues();
values.put("name","java");
getContentResolver().insert(MyProvider.URI, values);
values.put("name", "c");
getContentResolver().insert(MyProvider.URI, values);
values.put("name", "c++");
getContentResolver().insert(MyProvider.URI, values);
values.put("name","python");

getContentResolver().insert(MyProvider.URI,values);
}

public void onClickReadDB(View view){
Cursor cursor=getContentResolver().query(MyProvider.URI, null, null, null, null);
while (cursor.moveToNext()){
Log.i(TAG,cursor.getString(cursor.getColumnIndex("name")));
}
cursor.close();
}
}
3.布局文件
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity">

<TextView android:text="@string/hello_world" android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/textView" />

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="写入数据库"
android:onClick="onClickWriteDB"
android:id="@+id/button"
android:layout_below="@+id/textView"
android:layout_centerHorizontal="true"
android:layout_marginTop="88dp" />

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="查询数据库"
android:onClick="onClickReadDB"
android:id="@+id/button2"
android:layout_below="@+id/button"
android:layout_alignLeft="@+id/button"
android:layout_alignStart="@+id/button"
android:layout_marginTop="125dp" />

</RelativeLayout>