Android提高21篇之六：BroadcastReceiver

       前面分別討論了Activity和Service，這次就輪到BroastcastReceiver，Broastcast是應用程序間通信的手段。BroastcastReceiver也是跟Intent緊密相連的，動態/靜態注冊了BroastcastReceiver之後，使用sendBroadcast把Intent發送之後，系統會自動把符合條件的BroastcastReceiver啟動，跟嵌入式系統的中斷類似。

       本文主要演示了如何靜態/動態注冊BroastcastReceiver，向系統索取電量信息，以及枚舉信息的字段。本文運行截圖如下：

       上圖是發送Intent至內部動態注冊的BroadcastReceiver，接收到之後顯示消息名稱。動態注冊BroadcastReceiver用到registerReceiver()。

       上圖是發送Intent至內部靜態注冊的BroadcastReceiver，接收到之後顯示消息名稱。靜態注冊比動態注冊麻煩點，先新建一個類繼承BroadcastReceiver，然後到AndroidManifest.xml 添加

1. <receiver android:name="clsReceiver2">  
2.      <intent-filter>  
3.           <action android:name="com.testBroadcastReceiver.Internal_2"/>  
4.      </intent-filter>  
5. </receiver>  

       第一個name是類名，第二個是action的名稱。

       上圖是枚舉Intent消息的字段，這個功能比較適合懶人，把收到的Intent消息的字段全部分解了，再看看哪個需要的，懶得記住。實現這部分的代碼如下：

1. //當未知Intent包含的內容，則需要通過以下方法來列舉  
2. Bundle b=intent.getExtras();  
3. Object[] lstName=b.keySet().toArray();  
4.   
5. for(int i=0;i<lstname.length;i++)  
6. {  
7.     String keyName=lstName[i].toString();                                   
8.     Log.e(keyName,String.valueOf(b.get(keyName)));  
9. }  

       main.xml的代碼如下：

1. <linearlayout xmlns:android="http://schemas.android.com/apk/res/android"   
2.         android:orientation="vertical" android:layout_width="fill_parent"  
3.         android:layout_height="fill_parent">  
4.   
5.         <button android:id="@+id/Button01" android:layout_width="wrap_content"   
6.                 android:layout_height="wrap_content" android:text="發送至內部動態注冊的BroadcastReceiver">  
7.         <button android:id="@+id/Button02" android:layout_width="wrap_content"   
8.                 android:layout_height="wrap_content" android:text="發送至內部靜態注冊BroadcastReceiver">  
9.         <button android:id="@+id/Button03" android:layout_width="wrap_content"   
10.                 android:layout_height="wrap_content" android:text="發送至系統BroadcastReceiver">  

       testBroadcastReceiver.java的代碼如下：

1. package com.testBroadcastReceiver;  
2.   
3. import android.app.Activity;  
4. import android.content.BroadcastReceiver;  
5. import android.content.Context;  
6. import android.content.Intent;  
7. import android.content.IntentFilter;  
8. import android.os.Bundle;  
9. import android.util.Log;  
10. import android.view.View;  
11. import android.widget.Button;  
12. import android.widget.Toast;  
13.   
14. public class testBroadcastReceiver extends Activity {  
15.     Button btnInternal1,btnInternal2,btnSystem;  
16.     static final String INTENAL_ACTION_1 = "com.testBroadcastReceiver.Internal_1";  
17.     static final String INTENAL_ACTION_2 = "com.testBroadcastReceiver.Internal_2";  
18.     static final String INTENAL_ACTION_3 = "com.testBroadcastReceiver.Internal_3";  
19.     @Override  
20.     public void onCreate(Bundle savedInstanceState) {  
21.         super.onCreate(savedInstanceState);  
22.         setContentView(R.layout.main);  
23.         btnInternal1=(Button)this.findViewById(R.id.Button01);  
24.         btnInternal1.setOnClickListener(new ClickEvent());  
25.         btnInternal2=(Button)this.findViewById(R.id.Button02);  
26.         btnInternal2.setOnClickListener(new ClickEvent());  
27.         btnSystem=(Button)this.findViewById(R.id.Button03);  
28.         btnSystem.setOnClickListener(new ClickEvent());  
29.         //動態注冊廣播消息  
30.                 registerReceiver(bcrIntenal1, new IntentFilter(INTENAL_ACTION_1));  
31.     }  
32.     class ClickEvent implements View.OnClickListener{  
33.   
34.                 @Override  
35.                 public void onClick(View v) {  
36.                         if(v==btnInternal1)//給動態注冊的BroadcastReceiver發送數據  
37.                         {  
38.                                 Intent intent = new Intent(INTENAL_ACTION_1);  
39.                                 sendBroadcast(intent);  
40.                         }  
41.                         else if(v==btnInternal2)//給靜態注冊的BroadcastReceiver發送數據  
42.                         {  
43.                                 Intent intent = new Intent(INTENAL_ACTION_2);  
44.                                 sendBroadcast(intent);  
45.                         }  
46.                         else if(v==btnSystem)//動態注冊 接收2組信息的BroadcastReceiver  
47.                         {  
48.                                 IntentFilter filter = new IntentFilter();//  
49.                         filter.addAction(Intent.ACTION_BATTERY_CHANGED);//系統電量檢測信息  
50.                         filter.addAction(INTENAL_ACTION_3);//第三組自定義消息  
51.                                 registerReceiver(batInfoReceiver, filter);  
52.                                   
53.                                 Intent intent = new Intent(INTENAL_ACTION_3);  
54.                                 intent.putExtra("Name", "hellogv");  
55.                                 intent.putExtra("Blog", "http://blog.csdn.net/hellogv");  
56.                                 sendBroadcast(intent);//傳遞過去  
57.                         }  
58.                 }  
59.               
60.     }  
61.       
62.     /* 
63.      * 接收動態注冊廣播的BroadcastReceiver 
64.      */  
65.         private BroadcastReceiver bcrIntenal1 = new BroadcastReceiver() {  
66.                   
67.                 public void onReceive(Context context, Intent intent) {  
68.                         String action = intent.getAction();  
69.                         Toast.makeText(context, "動態:"+action, 1000).show();  
70.                 }  
71.         };  
72.           
73.   
74.         private BroadcastReceiver batInfoReceiver = new BroadcastReceiver() {  
75.                   
76.                 public void onReceive(Context context, Intent intent) {  
77.                         String action = intent.getAction();  
78.                         //如果捕捉到的action是ACTION_BATTERY_CHANGED  
79.                         if (Intent.ACTION_BATTERY_CHANGED.equals(action)) {  
80.                                 //當未知Intent包含的內容，則需要通過以下方法來列舉  
81.                                 Bundle b=intent.getExtras();  
82.                                 Object[] lstName=b.keySet().toArray();  
83.   
84.                                 for(int i=0;i<lstname.length;i++)  
85.                                 {  
86.                                         String keyName=lstName[i].toString();  
87.                                         Log.e(keyName,String.valueOf(b.get(keyName)));  
88.                                 }  
89.                         }  
90.                         //如果捕捉到的action是INTENAL_ACTION_3  
91.                         if (INTENAL_ACTION_3.equals(action)) {  
92.                                 //當未知Intent包含的內容，則需要通過以下方法來列舉  
93.                                 Bundle b=intent.getExtras();  
94.                                 Object[] lstName=b.keySet().toArray();  
95.   
96.                                 for(int i=0;i<lstname.length;i++)  
97.                                 {  
98.                                         String keyName=lstName[i].toString();  
99.                                         Log.e(keyName,b.getString(keyName));  
100.                                 }  
101.                         }  
102.                 }  
103.         };  
104. }  

       clsReceiver2.java的代碼如下：

1. package com.testBroadcastReceiver;  
2.   
3. import android.content.BroadcastReceiver;  
4. import android.content.Context;  
5. import android.content.Intent;  
6. import android.widget.Toast;  
7.   
8. /* 
9. * 接收靜態注冊廣播的BroadcastReceiver， 
10. * step1:要到AndroidManifest.xml這裡注冊消息 
11. *                  
12.   <action 
13.       android:name="com.testBroadcastReceiver.Internal_2"/> 
14.   </action 
15.  
16.   step2:定義消息的字符串 
17.   step3:通過Intent傳遞消息來驅使BroadcastReceiver觸發 
18. */  
19. public class clsReceiver2 extends BroadcastReceiver{  
20.         @Override  
21.         public void onReceive(Context context, Intent intent) {  
22.                 String action = intent.getAction();  
23.                 Toast.makeText(context, "靜態:"+action, 1000).show();  
24.                   
25.         }  
26. }