Android 使用ContentObserver监听数据库内容是否更改

public final void registerContentObserver
(
Uri uri, boolean notifyForDescendents, ContentObserver observer
)

import android.content.Context; 
import android.database.ContentObserver; 
import android.database.Cursor; 
import android.net.Uri; 
import android.os.Handler; 
import android.util.Log; 
  
  
//用来观察系统里短消息的数据库变化 ”表“内容观察者,只要信息数据库发生变化，都会触发该ContentObserver 派生类 
public class SMSContentObserver extends ContentObserver { 
  private static String TAG = "SMSContentObserver"; 
    
  private int MSG_OUTBOXCONTENT = 2 ; 
    
  private Context mContext ; 
  private Handler mHandler ;  //更新UI线程 
    
  public SMSContentObserver(Context context,Handler handler) { 
    super(handler); 
    mContext = context ; 
    mHandler = handler ; 
  } 
  /** 
   * 当所监听的Uri发生改变时，就会回调此方法 
   * 
   * @param selfChange 此值意义不大 一般情况下该回调值false 
   */ 
  @Override 
  public void onChange(boolean selfChange){ 
    Log.i(TAG, "the sms table has changed"); 
      
    //查询发件箱里的内容    
    Uri outSMSUri = Uri.parse("content://sms/sent") ; 
      
    Cursor c = mContext.getContentResolver().query(outSMSUri, null, null, null,"date desc"); 
    if(c != null){ 
        
      Log.i(TAG, "the number of send is"+c.getCount()) ; 
        
      StringBuilder sb = new StringBuilder() ; 
      //循环遍历 
      while(c.moveToNext()){ 
        sb.append("发件人手机号码: "+c.getInt(c.getColumnIndex("address"))) 
         .append("信息内容: "+c.getString(c.getColumnIndex("body"))) 
         .append("\n"); 
      } 
      c.close();      
      mHandler.obtainMessage(MSG_OUTBOXCONTENT, sb.toString()).sendToTarget();     
    } 
  } 
    
} 

import android.app.Activity; 
import android.database.Cursor; 
import android.net.Uri; 
import android.os.Bundle; 
import android.os.Handler; 
import android.os.Message; 
import android.provider.*; 
import android.util.Log; 
import android.widget.EditText; 
import android.widget.TextView; 
  
public class MainActivity extends Activity { 
  
  private TextView tvAirplane; 
  private EditText etSmsoutbox; 
  
  private SMSContentObserver smsContentObserver; 
  
  /** Called when the activity is first created. */ 
  @Override 
  public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.main); 
  
    etSmsoutbox = (EditText) findViewById(R.id.smsoutboxContent); 
  
    smsContentObserver = new SMSContentObserver(this, mHandler); 
      
    //注册内容观察者 
    registerContentObservers() ; 
  } 
  
  private void registerContentObservers() { 
    // ”表“内容观察者 ，通过测试我发现只能监听此Uri -----> content://sms 
    // 监听不到其他的Uri 比如说 content://sms/outbox 
    Uri smsUri = Uri.parse("content://sms"); 
    getContentResolver().registerContentObserver(smsUri, true,smsContentObserver); 
  } 
  
  private Handler mHandler = new Handler() { 
  
    public void handleMessage(Message msg) { 
        String outbox = (String) msg.obj; 
        etSmsoutbox.setText(outbox); 
      } 
    } 
  }; 
}