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Android編程之監(jiān)聽(tīng)器用法實(shí)例分析

更新時(shí)間：2016年01月04日 11:07:23 作者：傅榮康

這篇文章主要介紹了Android編程之監(jiān)聽(tīng)器用法,結(jié)合實(shí)例形式較為詳細(xì)的分析了Android監(jiān)聽(tīng)器的功能及針對(duì)短信的監(jiān)聽(tīng)與響應(yīng)操作技巧,需要的朋友可以參考下

本文實(shí)例講述了Android編程之監(jiān)聽(tīng)器用法。分享給大家供大家參考，具體如下：

這里通過(guò)監(jiān)聽(tīng)內(nèi)容提供者數(shù)據(jù)變化和監(jiān)聽(tīng)發(fā)送短信進(jìn)行講解監(jiān)聽(tīng)器。如果用戶提供者數(shù)據(jù)發(fā)生了變化，監(jiān)聽(tīng)器立刻就能收到對(duì)數(shù)據(jù)庫(kù)操作的記錄，而監(jiān)聽(tīng)器是采用通知的機(jī)制，如果不采用通知的機(jī)制也可以做，那就是不斷的查詢數(shù)據(jù)庫(kù)，這樣的話效率就會(huì)很低。而采用通知機(jī)制的話，當(dāng)用戶向數(shù)據(jù)庫(kù)發(fā)送一條記錄，ContentObserver立刻就能獲取到，我們就可以進(jìn)行處理數(shù)據(jù)。

監(jiān)聽(tīng)內(nèi)容提供者數(shù)據(jù)的變化

1.在內(nèi)容提供者中可以通知其他程序數(shù)據(jù)發(fā)生變化時(shí)進(jìn)行監(jiān)聽(tīng)

通過(guò)Context的getContentResolver()方法獲取ContentResolver

調(diào)用其notifyChange()方法發(fā)送數(shù)據(jù)修改通知

2.在其他程序中可以通過(guò)ContentObserver監(jiān)聽(tīng)數(shù)據(jù)變化

通過(guò)Context的getContentResolver()方法獲取ContentResolver

調(diào)用其registerContentObserver()方法指定對(duì)某個(gè)Uri注冊(cè)ContentObserver

自定義ContentObserver，重寫(xiě)onChange()方法獲取數(shù)據(jù)

比如在用戶插入數(shù)據(jù)的時(shí)候進(jìn)行監(jiān)聽(tīng)通知：

public Uri insert(Uri uri, ContentValues values) {
  SQLiteDatabase db = helper.getWritableDatabase();
  switch (matcher.match(uri)) {
    case PERSON_ALL:
      long id = db.insert("person", "id", values);
      // 監(jiān)聽(tīng)通知
      getContext().getContentResolver().notifyChange(uri, null);
      return ContentUris.withAppendedId(uri, id);
    default:
      throw new IllegalArgumentException("Unmatch Uri: " + uri);
  }
}

在另外一個(gè)工程中進(jìn)行監(jiān)聽(tīng),一旦用戶進(jìn)行插入操作，我立刻就可以自動(dòng)獲取到用戶插入的記錄：

public class MainActivity extends Activity {
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    getContentResolver().registerContentObserver(Uri.parse("content://cn.itcast.provider.itcast/person"), true, new MyObserver(new Handler()));
  }
  class MyObserver extends ContentObserver {
    public MyObserver(Handler handler) {
      super(handler);
    }
    //當(dāng)監(jiān)聽(tīng)到數(shù)據(jù)發(fā)生了變化就調(diào)用這個(gè)方法，并將新添加的數(shù)據(jù)查詢出來(lái)
    public void onChange(boolean selfChange) {
      ContentResolver resolver = getContentResolver();
      Uri uri = Uri.parse("content://cn.itcast.provider.itcast/person");
      Cursor cursor = resolver.query(uri, new String[] { "id", "name", "phone", "balance" }, null, null, "id DESC LIMIT 1");
      while (cursor.moveToNext()) {
        System.out.print(cursor.getString(0) + " ");
        System.out.print(cursor.getString(1) + " ");
        System.out.print(cursor.getString(2) + " ");
        System.out.println(cursor.getString(3));
      }
    }
  }
}

監(jiān)聽(tīng)發(fā)送短信

1.Android系統(tǒng)提供了Provider對(duì)短信進(jìn)行查詢，當(dāng)發(fā)出短信時(shí)也會(huì)發(fā)送更改通知

2.定義一個(gè)Observer監(jiān)聽(tīng)"content://sms"

3.在onChange()方法中查詢用戶發(fā)送的短信"content://sms/outbox"

4.短信發(fā)送信息存放在數(shù)據(jù)庫(kù) date/date/com.android.providers.telephony

5.需要權(quán)限<uses-permission android:name="android.permission.READ_SMS" />

示例：

public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);
  getContentResolver().registerContentObserver(Uri.parse("content://sms"), true, new SmsObserver(new Handler()));
}
//監(jiān)聽(tīng)發(fā)送的短信
private final class SmsObserver extends ContentObserver {
  public SmsObserver(Handler handler) {
    super(handler);
  }
  public void onChange(boolean selfChange) {
    ContentResolver resolver = getContentResolver();
    //查到發(fā)出的短信
    Uri uri = Uri.parse("content://sms/outbox");
    Cursor cursor = resolver.query(uri, new String[] { "date", "address", "body" }, null, null, "_id desc limit 1");
    if (cursor.moveToNext()) {
      long ms = cursor.getLong(0);
      String date = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date(ms));
      String address = cursor.getString(1);
      String body = cursor.getString(2);
      System.out.println(date + " " + address + " " + body);
    }
  }
}

希望本文所述對(duì)大家Android程序設(shè)計(jì)有所幫助。

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