ContentObserver——内容观察者，可以观察特定uri的数据库的变化，已达到监听的目的，进而对数据库的变化作出相应的反应。下面是一个监听短信变化的应用。
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Uri uri = Uri.parse("content://sms/");
getContentResolver().registerContentObserver(uri, true, new SmsObserver(new Handler()));
}
public class SmsObserver extends ContentObserver{
public SmsObserver(Handler handler) {
super(handler);
}
//当短信数据库发生改变时，触发此方法
@Override
public void onChange(boolean selfChange) {
System.out.println("您有新短信产生！");
//获取游标，对数据库进行操作
Cursor cursor = getContentResolver().query(Uri.parse("content://sms/outbox"), null, null, null, null);
while(cursor.moveToNext()){
StringBuilder sBuilder = new StringBuilder();
sBuilder.append("id=").append(cursor.getInt(cursor.getColumnIndex("_id")));
sBuilder.append(";address=").append(cursor.getString(cursor.getColumnIndex("address")));
sBuilder.append(";body=").append(cursor.getString(cursor.getColumnIndex("body")));
sBuilder.append(";time=").append(cursor.getString(cursor.getColumnIndex("date")));
//Toast.makeText(MainActivity.this, sBuilder.toString(), Toast.LENGTH_LONG).show();
String message = sBuilder.toString();
System.out.println(message);
TextView textView = (TextView) MainActivity.this.findViewById(R.id.tv_message);
textView.setText("你有短信了\n"+message);
}
super.onChange(selfChange);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}