【Android学习】Android广播机制

在Android中实现广播，首先我们要在Manifest.xml文件中配置一个标签，这个标签必须有一个android:name属性，值为继承自BroadcastReceiver类的接收器类！这个标签还有一个子标签为,这个标签很重要，是指定接收器需要接收哪种广播。另外，还有配置一个用户权限：,具体的值可以参考官方API文档。
另外一个比较重要的步骤是必须有一个类继承自BroadcastReceiver类，并复写onReceiver方法，在该方法中处理接收到广播后需要处理的事情！
下面来看一个具体的例子，有助于更好的理解广播机制是怎么一回事。
UI部分就不说了，Activity上就加了一个按钮，点击后发送广播。接收器接收到广播后在终端输出一句话。
首先看AndroidManifest.xml文件：
 ```

        

                
                        
                                
                                
                        
                

                      

下面是Activity：  
package com.gufengxiachen.broadcast;

import android.app.Activity;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class BroadCast extends Activity {
        /** Called when the activity is first created. */
private Button bound =null;
private Button unbound =null;
private Button sendBroadCast =null;
private SecondBroadCastReceiver sbr =null;

public static final String SMS_ACTION="android.provider.Telephony.SMS_RECEVIER";

@Override
        public void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
                setContentView(R.layout.main);
                bound = (Button)findViewById(R.id.bound);
                unbound = (Button)findViewById(R.id.unbound);
                sendBroadCast = (Button)findViewById(R.id.sendBroadCast);
                bound.setOnClickListener(new BoundListener());
                unbound.setOnClickListener(new UnboundListener());
                sendBroadCast.setOnClickListener(new SendBroadCast());
        }
        class SendBroadCast implements OnClickListener{
        @Override
        public void onClick(View v) {
        // TODO Auto-generated method stub
    
        Intent intent = new Intent(Intent.ACTION_EDIT);
        BroadCast.this.sendBroadcast(intent);
        }
        }
        
        class BoundListener implements OnClickListener{
        @Override
        public void onClick(View v) {
        // TODO Auto-generated method stub
        sbr = new SecondBroadCastReceiver();
        IntentFilter filter = new IntentFilter();
        filter.addAction(SMS_ACTION);
        BroadCast.this.registerReceiver(sbr, filter);        
        }
        }
        
class UnboundListener implements OnClickListener{
    
        @Override
        public void onClick(View v) {
        // TODO Auto-generated method stub
        BroadCast.this.unregisterReceiver(sbr);
        }

}
}

最后是接收器类：  
package com.gufengxiachen.broadcast;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;

public class MyBroadCastReceiver extends BroadcastReceiver{
public MyBroadCastReceiver(){

}
@Override
public void onReceive(Context context, Intent intent) {

System.out.println("message receiver");
}
}