Android ContentProvider实现获取手机联系人功能

package com.example.content; 
 
import android.content.ContentResolver; 
import android.database.Cursor; 
import android.net.Uri; 
import android.support.v7.app.AppCompatActivity; 
import android.os.Bundle; 
import android.util.Log; 
import android.view.View; 
 
public class MainActivity extends AppCompatActivity { 
 
 private ContentResolver cr; 
 
 @Override 
 protected void onCreate(Bundle savedInstanceState) { 
  super.onCreate(savedInstanceState); 
  setContentView(R.layout.activity_main); 
  //获取内容访问者 
  cr = getContentResolver(); 
 } 
 public void getContacts(View view){ 
  Uri uri=Uri.parse("content://com.android.contacts/raw_contacts"); 
  Cursor cursor=cr.query(uri,null,null,null,null); 
  while(cursor.moveToNext()){ 
   int _id=cursor.getInt(cursor.getColumnIndex("_id")); 
   String display_name=cursor.getString(cursor.getColumnIndex("display_name")); 
   Log.i("test",_id+" "+display_name); 
   Uri uriData=Uri.parse("content://com.android.contacts/raw_contacts/"+_id+"/data"); 
   Cursor cursorData=cr.query(uriData,null,null,null,null); 
   while(cursorData.moveToNext()){ 
    String mimetype=cursorData.getString(cursorData.getColumnIndex("mimetype")); 
    String data1=cursorData.getString(cursorData.getColumnIndex("data1")); 
    if("vnd.android.cursor.item/phone_v2".equals(mimetype)){ 
     Log.i("test","  "+mimetype+" "+data1); 
    } 
   } 
  } 
 } 
} 

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout 
 xmlns:android="http://schemas.android.com/apk/res/android" 
 xmlns:app="http://schemas.android.com/apk/res-auto" 
 xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" 
 android:layout_height="match_parent" tools:context="com.example.content.MainActivity"> 
 
 <Button 
  android:layout_width="wrap_content" 
  android:layout_height="wrap_content" 
  android:text="获取手机联系人" 
  android:onClick="getContacts" 
  /> 
 
</LinearLayout> 

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.content"> 
 
 <!--获取手机的联系人--> 
 <uses-permission android:name="android.permission.READ_CONTACTS"></uses-permission> 
 
 <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> 
 </application> 
 
</manifest>