public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        ContentResolver resolver = getContentResolver();
        Uri uri = Uri.parse("content://sms/");
        //注册
        resolver.registerContentObserver(uri, true, new MyObserver(new Handler()));                   
    }
    
    class MyObserver extends ContentObserver
    {

        public MyObserver(Handler handler) {
            super(handler);            
        }

        //当内容观察者观察到数据库的内容发生了变化就会调用这个方法
        //观察到消息邮箱里有一条数据库内容变化的通知
        @Override
        public void onChange(boolean selfChange) {
            super.onChange(selfChange);
            Toast.makeText(MainActivity.this, "数据库的内容发生了变化", Toast.LENGTH_LONG).show();
            Uri uri = Uri.parse("content://sms/");
            ContentResolver resolver = getContentResolver();
            Cursor cursor = resolver.query(uri, new String[]{"address" ,"date", "type", "body"}, null, null, null);
            cursor.moveToFirst();
            String address = cursor.getString(cursor.getColumnIndex("address"));
            String body = cursor.getString(cursor.getColumnIndex("body"));
            System.out.println("address"+address+"+++++++body:"+body);
            cursor.close();
        }                  
    }    
}