Android入門:廣播發送者與廣播接收者
一、廣播發送者&廣播接收者介紹
1.廣播接收者
廣播接收者簡單地說就是接收廣播意圖的Java類,此Java類繼承BroadcastReceiver類,重寫:
public void onReceive(Context context,Intent intent),其中intent可以獲得傳遞的資料;
廣播意圖就是通過Context.sendBroadcast(Intent intent)或Context.sendOrderedBroadcast(Intent intent)發送的意圖,通過這個語句,能夠廣播給所有滿足條件的元件,比如intent設定了action="com.xiazdong",則所有在AndroidManifest.xml中設定過<action android:name="com.xiazdong"/>的廣播接收者都能夠接收到廣播;
2.廣播發送者
通常廣播發送方就是調用Context.sendBroadcast()的程式,而廣播接收者就是繼承BroadcastReceiver的程式;
通常廣播發送方都是通過隐式意圖,這樣才能發送給多人;
廣播發送方分為普通廣播和有序廣播;
同步廣播:發送方發出後,幾乎同時到達多個廣播接收者處,某個接收者不能接收到廣播後進行一番處理後傳給下一個接收者,并且無法終止廣播繼續傳播;Context.sendBroadcast(intent);
有序廣播:廣播接收者需要提前設定優先級,優先級高的先接收到廣播,優先級數值為-1000~1000,在AndroidManifest.xml的<intent-filter android:priority="xxx">設定;比如存在3個廣播接收者A、B、C,優先級A>B>C,是以A最先收到廣播,當A收到廣播後,可以向廣播中添加一些資料給下一個接收者(intent.putExtra()),或者終止廣播(abortBroadcast());Context.sendOrderedBroadcast(intent);
二、廣播接收者核心代碼
同步廣播發送方核心代碼:
1 | Intent intent = new Intent(); |
2 | intent.setAction( "..." ); |
3 | Context.sendBroadcast(intent); |
有序廣播發送方核心代碼:
Intent intent = new Intent();
intent.setAction("...");
Context.sendOrderedBroadcast(intent,null);
廣播接收者核心代碼:
1 | public class Receiver extends BroadcastReceiver{ |
2 | public void onReceive(Context context, Intent intent) { |
3 | Bundle bundle = intent.getExtras(); |
AndroidManifest.xml
<application>
<receiver android:name=".Receiver">
<intent-filter android:priority="1000">
<action android:name="com.xiazdong"/>
</intent-filter>
</receiver>
</application>
三、廣播執行個體
1.同步廣播執行個體
場景說明:
(1)廣播發送者:
01 | package com.xiazdong.broadcastsender; |
03 | import android.app.Activity; |
04 | import android.content.Intent; |
05 | import android.os.Bundle; |
06 | import android.view.View; |
07 | import android.view.View.OnClickListener; |
08 | import android.widget.Button; |
09 | import android.widget.Toast; |
11 | public class MainActivity extends Activity { |
12 | private Button button; |
13 | private OnClickListener listener = new OnClickListener(){ |
15 | public void onClick(View v) { |
16 | Intent intent = new Intent(); |
17 | intent.setAction( "com.xiazdong" ); |
18 | intent.putExtra( "name" , "xiazdong" ); |
19 | MainActivity. this .sendBroadcast(intent); |
20 | Toast.makeText(getApplicationContext(), "發送廣播成功" , Toast.LENGTH_SHORT).show(); |
24 | public void onCreate(Bundle savedInstanceState) { |
25 | super .onCreate(savedInstanceState); |
26 | setContentView(R.layout.main); |
27 | button = (Button) this .findViewById(R.id.button); |
28 | button.setOnClickListener(listener); |
(2)廣播接收者
01 | package com.xiazdong.broadcastreceiver1; |
03 | import android.content.BroadcastReceiver; |
04 | import android.content.Context; |
05 | import android.content.Intent; |
06 | import android.util.Log; |
08 | public class Receiver extends BroadcastReceiver { |
11 | public void onReceive(Context context, Intent intent) { |
12 | String name = intent.getExtras().getString( "name" ); |
13 | Log.i( "Recevier1" , "接收到:" +name); |
AndroidManifest.xml
1 | <receiver android:name= ".Receiver" > |
3 | <action android:name= "com.xiazdong" /> |
結果:
2.有序廣播執行個體
場景說明:
(1)廣播發送者
01 | package com.xiazdong.broadcastsender; |
03 | import android.app.Activity; |
04 | import android.content.Intent; |
05 | import android.os.Bundle; |
06 | import android.view.View; |
07 | import android.view.View.OnClickListener; |
08 | import android.widget.Button; |
09 | import android.widget.Toast; |
11 | public class MainActivity extends Activity { |
12 | private Button button; |
13 | private OnClickListener listener = new OnClickListener(){ |
15 | public void onClick(View v) { |
16 | Intent intent = new Intent(); |
17 | intent.setAction( "com.xiazdong" ); |
18 | intent.putExtra( "name" , "xiazdong" ); |
19 | MainActivity. this .sendOrderedBroadcast(intent, null ); //有序廣播發送 |
20 | Toast.makeText(getApplicationContext(), "發送廣播成功" , Toast.LENGTH_SHORT).show(); |
24 | public void onCreate(Bundle savedInstanceState) { |
25 | super .onCreate(savedInstanceState); |
26 | setContentView(R.layout.main); |
27 | button = (Button) this .findViewById(R.id.button); |
28 | button.setOnClickListener(listener); |
(2)廣播接收者
Receiver1
檢視源碼 列印 ?
01 | package com.xiazdong.broadcastreceiver1; |
03 | import android.content.BroadcastReceiver; |
04 | import android.content.Context; |
05 | import android.content.Intent; |
06 | import android.util.Log; |
08 | public class Receiver extends BroadcastReceiver { |
11 | public void onReceive(Context context, Intent intent) { |
12 | String name = intent.getExtras().getString( "name" ); |
13 | Log.i( "Recevier1" , "接收到:" +name); |
14 | abortBroadcast(); //Receiver1接收到廣播後中斷廣播 |
AndroidManifest.xml
<receiver android:name=".Receiver">
<intent-filter android:priority="1000"> <!-- 設定最高優先級 -->
<action android:name="com.xiazdong"/>
</intent-filter>
</receiver>