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Android入门:广播发送者与广播接收者详细介绍

  • 时间:2020-03-10 11:20 编辑: 来源: 阅读:
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摘要:Android入门:广播发送者与广播接收者详细介绍
[b]一、广播发送者&广播接收者介绍[/b] [b]1.广播接收者[/b] 广播接收者简单地说就是接收广播意图的Java类,此Java类继承BroadcastReceiver类,重写: public void onReceive(Context context,Intent intent),其中intent可以获得传递的数据; 广播意图就是通过Context.sendBroadcast(Intent intent)或Context.sendOrderedBroadcast(Intent intent)发送的意图,通过这个语句,能够广播给所有满足条件的组件,比如intent设置了action="com.xiazdong",则所有在AndroidManifest.xml中设置过<action Android:name="com.xiazdong"/>的广播接收者都能够接收到广播; 注:onReceive方法必须在10秒内完成,如果没有完成,则抛“Application No Response”当广播接收者onReceive方法需要执行很长时间时,最好将此耗时工作通过Intent发送给Service,由Service完成,并且不能使用子线程解决,因为BroadcastReceiver是接收到广播后才创建的,并且生命周期很短,因此子线程可能在没有执行完就已经被杀死了。
public void onReceive(Context context,Intent intent){ 
  Intent intent = new Intent(context,XxxService.class); 
  context.startService(intent); 
} 
[b]2.广播发送者[/b] 通常广播发送方就是调用Context.sendBroadcast()的程序,而广播接收者就是继承BroadcastReceiver的程序; 通常广播发送方都是通过隐式意图,这样才能发送给多人; [b]广播发送方分为普通广播和有序广播;[/b] 同步广播:发送方发出后,几乎同时到达多个广播接收者处,某个接收者不能接收到广播后进行一番处理后传给下一个接收者,并且无法终止广播继续传播;Context.sendBroadcast(intent); 有序广播:广播接收者需要提前设置优先级,优先级高的先接收到广播,优先级数值为-1000~1000,在AndroidManifest.xml的<intent-filter android:priority="xxx">设置;比如存在3个广播接收者A、B、C,优先级A>B>C,因此A最先收到广播,当A收到广播后,可以向广播中添加一些数据给下一个接收者(intent.putExtra()),或者终止广播(abortBroadcast());Context.sendOrderedBroadcast(intent); [b]二、广播接收者核心代码[/b] 同步广播发送方核心代码:
Intent intent = new Intent(); 
intent.setAction("..."); 
Context.sendBroadcast(intent); 
有序广播发送方核心代码:
Intent intent = new Intent(); 
intent.setAction("..."); 
Context.sendOrderedBroadcast(intent,null); 
广播接收者核心代码:
public class Receiver extends BroadcastReceiver{ 
  public void onReceive(Context context, Intent intent) { 
    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>
[b]三、广播实例[/b] 1.同步广播实例[img]http://files.jb51.net/file_images/article/201611/2016118160342815.png?201610816355[/img] 场景说明: (1)广播发送者:
package com.xiazdong.broadcastsender; 
 
import android.app.Activity; 
import android.content.Intent; 
import android.os.Bundle; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.widget.Toast; 
 
public class MainActivity extends Activity { 
  private Button button; 
  private OnClickListener listener = new OnClickListener(){ 
    @Override 
    public void onClick(View v) { 
      Intent intent = new Intent(); 
      intent.setAction("com.xiazdong"); 
      intent.putExtra("name", "xiazdong"); 
      MainActivity.this.sendBroadcast(intent); 
      Toast.makeText(getApplicationContext(), "发送广播成功", Toast.LENGTH_SHORT).show(); 
    } 
  }; 
  @Override 
  public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.main); 
    button = (Button)this.findViewById(R.id.button); 
    button.setOnClickListener(listener); 
  } 
} 
(2)广播接收者
package com.xiazdong.broadcastreceiver1; 
 
import android.content.BroadcastReceiver; 
import android.content.Context; 
import android.content.Intent; 
import android.util.Log; 
 
public class Receiver extends BroadcastReceiver { 
 
  @Override 
  public void onReceive(Context context, Intent intent) { 
    String name = intent.getExtras().getString("name"); 
    Log.i("Recevier1", "接收到:"+name); 
  } 
 
}
  AndroidManifest.xml
<receiver android:name=".Receiver"> 
    <intent-filter> 
       <action android:name="com.xiazdong"/> 
    </intent-filter> 
</receiver> 
结果:[img]http://files.jb51.net/file_images/article/201611/2016118160412537.png?201610816420[/img] 2.有序广播实例 场景说明:[img]http://files.jb51.net/file_images/article/201611/2016118160435007.png?201610816442[/img] (1)广播发送者
package com.xiazdong.broadcastsender; 
 
import android.app.Activity; 
import android.content.Intent; 
import android.os.Bundle; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.widget.Toast; 
 
public class MainActivity extends Activity { 
  private Button button; 
  private OnClickListener listener = new OnClickListener(){ 
    @Override 
    public void onClick(View v) { 
      Intent intent = new Intent(); 
      intent.setAction("com.xiazdong"); 
      intent.putExtra("name", "xiazdong"); 
      MainActivity.this.sendOrderedBroadcast(intent, null);  //有序广播发送 
      Toast.makeText(getApplicationContext(), "发送广播成功", Toast.LENGTH_SHORT).show(); 
    } 
  }; 
  @Override 
  public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.main); 
    button = (Button)this.findViewById(R.id.button); 
    button.setOnClickListener(listener); 
  } 
} 
(2)广播接收者 Receiver1
package com.xiazdong.broadcastreceiver1; 
 
import android.content.BroadcastReceiver; 
import android.content.Context; 
import android.content.Intent; 
import android.util.Log; 
 
public class Receiver extends BroadcastReceiver { 
 
  @Override 
  public void onReceive(Context context, Intent intent) { 
    String name = intent.getExtras().getString("name"); 
    Log.i("Recevier1", "接收到:"+name); 
    abortBroadcast();  //Receiver1接收到广播后中断广播 
  } 
 
} 
AndroidManifest.xml
<receiver android:name=".Receiver"> 
   <intent-filter android:priority="1000"> <!-- 设置最高优先级 --> 
     <action android:name="com.xiazdong"/> 
   </intent-filter> 
 </receiver> 
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持编程素材网。
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