android学习笔记(16)广播事件处理

比眉伴天荒 2022-08-04 15:52 99阅读 0赞

对应苦水老师的[第二十课][Link 1]

广播是系统级别的,由系统级别的程序发出,广播的接收是不限制的,系统\\用户级都能接收处理.这让我想到了linux下的机器人操作系统ROS消息的发布与接收,其实两者是一个模式的.

**一,编程过程:**  
(1)新建包,新建类,继承自BroadcastReciver,然后复写方法onReceive并在里面处理接收来的广播.  
(2)在xml中注册broadcastreceiver  
注意 1,在新建包后,在XML中注册广播,需要用命名注册,即包名.类名  
2,需要在XML中加广播过渡器,你需要处理哪个广播就加哪个  
<intent-filter>  
<action android:name="com.szy.broadcast.ACTION"/>  
</intent-filter>  
3,如果接收系统广播得加权限  
<uses-permission android:name="android.permission.RECEIVE\_SMS"/>  
(3)构建intent对象  
(4)调用sendBroadcase()方法发送广播  
这个发送广播得理解一下, 发送的广播是没有内容的,我的理解是,广播有一个名字,比如abc,它相当于一个全局的bool类型,当执行了发送操作后,它就为true了,否则为false,接收方则一直处于监听abc的true or false状态.  
**二,生命周期:**

BroadcastReceiver对象仅在调用onReceiver()方法时有效,当该方法执行完毕捕后,系统认为销毁该对象.

**三，源码:**

**MainActivity**

package com.example1.broadcastdemo;
    
    import android.net.sip.SipAudioCall.Listener;
    import android.os.Bundle;
    import android.app.Activity;
    import android.content.Intent;
    import android.view.Menu;
    import android.view.View;
    import android.view.View.OnClickListener;
    import android.widget.Button;
    import android.widget.Toast;
    
    public class MainActivity extends Activity {
    protected static final String action = "com.example1.broadcastdemo.ACTION";
    private Button btnbc;
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            btnbc = (Button)findViewById(R.id.btnbc);
            btnbc.setOnClickListener(listener);
    
        }
    private OnClickListener listener = new OnClickListener() {
    	
    	@Override
    	public void onClick(View arg0) {
    	   Intent intent = new Intent();
    	   intent.setAction(action);
    	   sendBroadcast(intent);
    
    		
    	}
    };
        
    }

**Receiver**

package com.example1.receiver;
    import com.example1.broadcastdemo.ToastDemo;
    
    import android.content.BroadcastReceiver;
    import android.content.Context;
    import android.content.Intent;
    import android.util.Log;
    import android.widget.Toast;
    
    public class Receiver extends BroadcastReceiver {
    
    	private static final String tag = "Receiver";
    
    	@Override
    	public void onReceive(Context arg0, Intent arg1) {
    	Log.i(tag, "receive");
    	}
    
    }

XML

</activity>
            <receiver android:name="com.example1.receiver.Receiver">
            <intent-filter>
                <action android:name="com.example1.broadcastdemo.ACTION"/>
            </intent-filter>
            </receiver>

<uses-permission android:name="android.permission.RECEIVE_SMS"/>

[Link 1]: http://blog.csdn.net/coolszy/article/details/6396393