Android BroadcastReceiver 简介
在 Android 中使用 Activity, Service, Broadcast, BroadcastReceiver 活动(Activity) - 用于表现功能 服务(Service) - 相当于后台运行的 Activity 广播(Broadcast) - 用于发送广播 广播接收器(BroadcastReceiver) - 用于接收广播 Intent - 用于连接以上各个组件,并在其间传递消息 BroadcastReceiver 在Android中,Broadcast是一种广泛运用的在应用程序之间传输信息的机制。而BroadcastReceiver是对发送出来的 Broadcast进行过滤接受并响应的一类组件。下面将详细的阐述如何发送Broadcast和使用BroadcastReceiver过 滤接收的过程: 首先在需要发送信息的地方,把要发送的信息和用于过滤的信息(如Action、Category)装入一个Intent对象,然后通过调用 Context.sendBroadcast()、sendOrderBroadcast()或sendStickyBroadcast()方法,把 Intent对象以广播方式发送出去。 当Intent发送以后,所有已经注册的BroadcastReceiver会检查注册时的IntentFilter是否与发送的Intent相匹配,若 匹配则就会调用BroadcastReceiver的onReceive()方法。所以当我们定义一个BroadcastReceiver的时候,都需要 实现onReceive()方法。 注册BroadcastReceiver有两种方式: 一种方式是,静态的在AndroidManifest.xml中用<receiver>标签生命注册,并在标签内用<intent- filter>标签设置过滤器。 另一种方式是,动态的在代码中先定义并设置好一个 IntentFilter对象,然后在需要注册的地方调 Context.registerReceiver()方法,如果取消时就调用Context.unregisterReceiver()方法。如果用动 态方式注册的BroadcastReceiver的Context对象被销毁时,BroadcastReceiver也就自动取消注册了。 另外,若在使用sendBroadcast()的方法是指定了接收权限,则只有在AndroidManifest.xml中用<uses- permission>标签声明了拥有此权限的BroascastReceiver才会有可能接收到发送来的Broadcast。 同样,若在注册BroadcastReceiver时指定了可接收的Broadcast的权限,则只有在包内的AndroidManifest.xml中 用<uses-permission>标签声明了,拥有此权限的Context对象所发送的Broadcast才能被这个 BroadcastReceiver所接收。 动态注册: IntentFilter intentFilter = new IntentFilter(); intentFilter.addAction(String);--为 BroadcastReceiver指定action,使之用于接收同action的广播 registerReceiver(BroadcastReceiver,intentFilter); 一般:在onStart中注册,onStop中取消unregisterReceiver 发送广播消息:extends Service 指定广播目标Action:Intent Intent = new Intent(action-String) --指定了此action的receiver会接收此广播 需传递参数(可选) putExtra(); 发送:sendBroadcast(Intent); 前面分别讨论了Activity和Service,这次就轮到BroastcastReceiver,Broastcast是应用程序间通信的手段。BroastcastReceiver也是跟Intent紧密相连的,动态/静态注册了BroastcastReceiver之后,使用sendBroadcast把Intent发送之后,系统会自动把符合条件的BroastcastReceiver启动,跟嵌入式系统的中断类似。
本文主要演示了如何静态/动态注册BroastcastReceiver,向系统索取电量信息,以及枚举信息的字段。本文运行截图如下:
上图是发送Intent至内部动态注册的BroadcastReceiver,接收到之后显示消息名称。动态注册BroadcastReceiver用到registerReceiver()。 上图是发送Intent至内部静态注册的BroadcastReceiver,接收到之后显示消息名称。静态注册比动态注册麻烦点,先新建一个类继承BroadcastReceiver,然后到AndroidManifest.xml 添加
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01.<receiver android:name="clsReceiver2"> 02. <intent-filter> 03. <action 04. android:name="com.testBroadcastReceiver.Internal_2"/> 05. </intent-filter> 06.</receiver> <receiver android:name="clsReceiver2"> <intent-filter> <action android:name="com.testBroadcastReceiver.Internal_2"/> </intent-filter> </receiver> 第一个name是类名,第二个是action的名称。
上图是枚举Intent消息的字段,这个功能比较适合懒人,把收到的Intent消息的字段全部分解了,再看看哪个需要的,懒得记住。实现这部分的代码如下:
view plaincopy to clipboardprint? 01.//当未知Intent包含的内容,则需要通过以下方法来列举 02. Bundle b=intent.getExtras(); 03. Object[] lstName=b.keySet().toArray(); 04. 05. for(int i=0;i<lstName.length;i++) 06. { 07. String keyName=lstName[i].toString(); 08. Log.e(keyName,String.valueOf(b.get(keyName))); 09. } //当未知Intent包含的内容,则需要通过以下方法来列举 Bundle b=intent.getExtras(); Object[] lstName=b.keySet().toArray(); for(int i=0;i<lstName.length;i++)
{ String keyName=lstName[i].toString(); Log.e(keyName,String.valueOf(b.get(keyName))); } main.xml的代码如下:
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01.<?xml version="1.0" encoding="utf-8"?> 02.<LinearLayout xmlns:android="http://schemas./apk/res/android" 03. android:orientation="vertical" android:layout_width="fill_parent" 04. android:layout_height="fill_parent"> 05. 06. <Button android:id="@+id/Button01" android:layout_width="wrap_content" 07. android:layout_height="wrap_content" android:text="发送至内部动态注册的BroadcastReceiver"></Button> 08. <Button android:id="@+id/Button02" android:layout_width="wrap_content" 09. android:layout_height="wrap_content" android:text="发送至内部静态注册BroadcastReceiver"></Button> 10. <Button android:id="@+id/Button03" android:layout_width="wrap_content" 11. android:layout_height="wrap_content" android:text="发送至系统BroadcastReceiver"></Button> 12.</LinearLayout> <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas./apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent"> <Button android:id="@+id/Button01" android:layout_width="wrap_content"
android:layout_height="wrap_content" android:text="发送至内部动态注册的BroadcastReceiver"></Button> <Button android:id="@+id/Button02" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="发送至内部静态注册BroadcastReceiver"></Button> <Button android:id="@+id/Button03" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="发送至系统BroadcastReceiver"></Button> </LinearLayout> testBroadcastReceiver.java的代码如下:
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01.package com.testBroadcastReceiver; 02. 03.import android.app.Activity; 04.import android.content.BroadcastReceiver; 05.import android.content.Context; 06.import android.content.Intent; 07.import android.content.IntentFilter; 08.import android.os.Bundle; 09.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. //动态注册广播消息 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)//给动态注册的BroadcastReceiver发送数据 37. { 38. Intent intent = new Intent(INTENAL_ACTION_1); 39. sendBroadcast(intent); 40. } 41. else if(v==btnInternal2)//给静态注册的BroadcastReceiver发送数据 42. { 43. Intent intent = new Intent(INTENAL_ACTION_2); 44. sendBroadcast(intent); 45. } 46. else if(v==btnSystem)//动态注册 接收2组信息的BroadcastReceiver 47. { 48. IntentFilter filter = new IntentFilter();// 49. filter.addAction(Intent.ACTION_BATTERY_CHANGED);//系统电量检测信息 50. filter.addAction(INTENAL_ACTION_3);//第三组自定义消息 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);//传递过去 57. } 58. } 59. 60. } 61. 62. /* 63. * 接收动态注册广播的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, "动态:"+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. //当未知Intent包含的内容,则需要通过以下方法来列举 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. //当未知Intent包含的内容,则需要通过以下方法来列举 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. 105. 106.} package com.testBroadcastReceiver; import android.app.Activity;
import android.content.BroadcastReceiver; import android.content.Context; import android.content.Intent; import android.content.IntentFilter; import android.os.Bundle; import android.util.Log; import android.view.View; import android.widget.Button; import android.widget.Toast; public class testBroadcastReceiver extends Activity {
Button btnInternal1,btnInternal2,btnSystem; static final String INTENAL_ACTION_1 = "com.testBroadcastReceiver.Internal_1"; static final String INTENAL_ACTION_2 = "com.testBroadcastReceiver.Internal_2"; static final String INTENAL_ACTION_3 = "com.testBroadcastReceiver.Internal_3"; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); btnInternal1=(Button)this.findViewById(R.id.Button01); btnInternal1.setOnClickListener(new ClickEvent()); btnInternal2=(Button)this.findViewById(R.id.Button02); btnInternal2.setOnClickListener(new ClickEvent()); btnSystem=(Button)this.findViewById(R.id.Button03); btnSystem.setOnClickListener(new ClickEvent()); //动态注册广播消息 registerReceiver(bcrIntenal1, new IntentFilter(INTENAL_ACTION_1)); } class ClickEvent implements View.OnClickListener{ @Override
public void onClick(View v) { if(v==btnInternal1)//给动态注册的BroadcastReceiver发送数据 { Intent intent = new Intent(INTENAL_ACTION_1); sendBroadcast(intent); } else if(v==btnInternal2)//给静态注册的BroadcastReceiver发送数据 { Intent intent = new Intent(INTENAL_ACTION_2); sendBroadcast(intent); } else if(v==btnSystem)//动态注册 接收2组信息的BroadcastReceiver { IntentFilter filter = new IntentFilter();// filter.addAction(Intent.ACTION_BATTERY_CHANGED);//系统电量检测信息 filter.addAction(INTENAL_ACTION_3);//第三组自定义消息 registerReceiver(batInfoReceiver, filter); Intent intent = new Intent(INTENAL_ACTION_3); intent.putExtra("Name", "hellogv"); intent.putExtra("Blog", "http://blog.csdn.net/hellogv"); sendBroadcast(intent);//传递过去 } } } /* * 接收动态注册广播的BroadcastReceiver */ private BroadcastReceiver bcrIntenal1 = new BroadcastReceiver() { public void onReceive(Context context, Intent intent) { String action = intent.getAction(); Toast.makeText(context, "动态:"+action, 1000).show(); } }; private BroadcastReceiver batInfoReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) { String action = intent.getAction(); //如果捕捉到的action是ACTION_BATTERY_CHANGED if (Intent.ACTION_BATTERY_CHANGED.equals(action)) { //当未知Intent包含的内容,则需要通过以下方法来列举 Bundle b=intent.getExtras(); Object[] lstName=b.keySet().toArray(); for(int i=0;i<lstName.length;i++)
{ String keyName=lstName[i].toString(); Log.e(keyName,String.valueOf(b.get(keyName))); } } //如果捕捉到的action是INTENAL_ACTION_3 if (INTENAL_ACTION_3.equals(action)) { //当未知Intent包含的内容,则需要通过以下方法来列举 Bundle b=intent.getExtras(); Object[] lstName=b.keySet().toArray(); for(int i=0;i<lstName.length;i++)
{ String keyName=lstName[i].toString(); Log.e(keyName,b.getString(keyName)); } } } }; } clsReceiver2.java的代码如下:
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01.package com.testBroadcastReceiver; 02. 03.import android.content.BroadcastReceiver; 04.import android.content.Context; 05.import android.content.Intent; 06.import android.widget.Toast; 07. 08./* 09. * 接收静态注册广播的BroadcastReceiver, 10. * step1:要到AndroidManifest.xml这里注册消息 11. * <receiver android:name="clsReceiver2"> 12. <intent-filter> 13. <action 14. android:name="com.testBroadcastReceiver.Internal_2"/> 15. </intent-filter> 16. </receiver> 17. step2:定义消息的字符串 18. step3:通过Intent传递消息来驱使BroadcastReceiver触发 19. */ 20.public class clsReceiver2 extends BroadcastReceiver{ 21. @Override 22. public void onReceive(Context context, Intent intent) { 23. String action = intent.getAction(); 24. Toast.makeText(context, "静态:"+action, 1000).show(); 25. 26. } 27.} 本文来自CSDN博客,转载请标明出处:http://blog.csdn.net/hellogv/archive/2010/11/10/5999170.aspx |
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