008_03_ContentResolver

 Context提供了getContentResolver()方法，这表明Activity，service等组建都可以通过getContentResolver()方法获取对象。获取ContentResolver对象之后，接下来就可调用ContentResolver的query(),insert(),update(),delete()方法，实际上指定Uri对应的ContentProvider的query(),insert(),update(),delete()方法

package com.example.day08_contentvisitor;

import android.app.Activity;
import android.content.ContentValues;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
    
    public void delete(View v){
        getContentResolver().delete(Uri.parse("content://com.example.mycontentprovider"), "id=?", new String[]{"1"});
    }
    public void update(View v){
        ContentValues c2 = new ContentValues();
        c2.put("name", "zhaosi");
        c2.put("telephone", "18888888888");
        getContentResolver().update(Uri.parse("content://com.example.mycontentprovider"), c2, "id=?", new String[]{"4"});
    }
    public void insert(View v){
        ContentValues c = new ContentValues();
        c.put("id", 1);
        c.put("name", "zhangsan");
        c.put("telephone", "13899999999");
        getContentResolver().insert(Uri.parse( "content://com.example.mycontentprovider"), c);
    }
    public void insert2(View v){
        ContentValues c = new ContentValues();
        c.put("id", 1);
        c.put("name", "zhangsan");
        c.put("wechat", "zhansanfeng");
        
        getContentResolver().insert(Uri.parse( "content://com.example.mycontentprovider/userwechat"), c);        
    }
    
    public void query(View v){
          Cursor c=    getContentResolver().query(Uri.parse( "content://com.example.mycontentprovider/userphonenum"),
                    new String[]{"id","name" ,"telephone"}, null,null, null);
        
          while (c.moveToNext()) {
              int id  = c.getInt(0);
              String name = c.getString(1);
              String number = c.getString(2);
              
              Log.i("mycontentvisitor", id+","+name+","+number);
        }
    }
    
    public void query2(View v){
        
          Cursor c=    getContentResolver().query(Uri.parse( "content://com.cskaoyan.mycontentprovider/userwechat/4"),
                    new String[]{"id","name" ,"wechat"}, null,null, null);
        
          while (c.moveToNext()) {
              int id  = c.getInt(0);
              String name = c.getString(1);
              String number = c.getString(2);
              
              Log.i("mycontentvisitor", id+","+name+","+number);
        }
    }
    
    public void query3(View v){
        
          Cursor c=    getContentResolver().query(Uri.parse( "content://com.cskaoyan.mycontentprovider/userwechat/wechat"),
                    null, null,null, null);
        
          while (c.moveToNext()) {
              String wechat  = c.getString(0);
              Log.i("mycontentvisitor", wechat);
          }
            
        }
}

<LinearLayout 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:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.mycontentvisitor.MainActivity" >

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

    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:onClick="delete"
        android:text="delete" />

    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:onClick="insert"
        android:text="insert" />

    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:onClick="update"
        android:text="update" />

    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:onClick="query"
        android:text="query" />

    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:onClick="insert2"
        android:text="insertinto wechat" />
    
    
    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:onClick="query2"
        android:text="query one from wechat" />

    
    <Button
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:onClick="query3"
        android:text="query name from wechat" />
</LinearLayout>