android学习笔记(17)广播事件处理进阶(注册方法)

ゝ一纸荒年。 2022-08-04 15:53 84阅读 0赞

前一课学习了广播的接收，用的是粗犷的方法，下面学学实用的。也就是它的注册方法。

注册BroadcastReceiver的方法:

1,在AndroidManifest.xml文件中进行注册  
这种方法是最简单的,但是有个很大有问题是,这个recevicer与activity是无关的,当程序退出后,这个receiver仍然在运行,比如你的recevier调用了camera,当你用其它方式打开camera时,camera就在被占用的状态,就会出问题.  
2,在应用程序的代码中进行注册  
注册:  
registerReceiver()  
取消注册:

unregisterReceiver()

**源码**

MainActivity

package com.example1.broadcastdemo;
    
    
    import com.example1.receiver.Receiver;
    
    
    import android.net.sip.SipAudioCall.Listener;
    import android.os.Bundle;
    import android.app.Activity;
    import android.content.Intent;
    import android.content.IntentFilter;
    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;
    private Button btnregister;
    private Button btnunregister;
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            btnbc = (Button)findViewById(R.id.btnbc);
            btnregister = (Button)findViewById(R.id.btnregister);
            btnunregister = (Button)findViewById(R.id.btnunregister);
            btnbc.setOnClickListener(listener);
            btnregister.setOnClickListener(listener);
            btnunregister.setOnClickListener(listener);
    
    
        }
    private OnClickListener listener = new OnClickListener() {
    	  Intent intent = new Intent();
    	  Receiver receiver;
    	@Override
    	public void onClick(View v) {
    		switch (v.getId()) {
    		case R.id.btnbc:
    			  intent.setAction(action);
    			   sendBroadcast(intent);
    			break;
    		case R.id.btnregister:
    			receiver = new Receiver();
    			IntentFilter filter = new IntentFilter();
    			filter.addAction(action);
    			registerReceiver(receiver, filter);
    			break;
    		case R.id.btnunregister:
    			 unregisterReceiver(receiver);
    			break;
    		default:
    			break;
    		}
    	 
    	 
    
    
    		
    	}
    };
        
    }

Receiver.java(在另一个包中)

package com.example1.receiver;
    import com.example1.broadcastdemo.MainActivity;
    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 {
    
    
    	@Override
    	public void onReceive(Context arg0, Intent arg1) {
    
    	Toast toast = Toast.makeText(arg0, "收到广播", Toast.LENGTH_SHORT);
    	toast.show();
    	}
    
    }

**点击register后再点击broadcast:能收到广播。**

![20150906151624537][]

**之前没有点击register或者点击了unregister后点击broadcast:都是收不到广播的。**

![20150906151629660][]  
  
附:

# [\[Android\] Android系统广播Action][Android_ Android_Action] #

[20150906151624537]: /images/20220731/ca20245b36e34f42935e3f9fc1dc23f1.png
[20150906151629660]: /images/20220731/4c090a7c50e34e7a96bb0e92ce0c0298.png
[Android_ Android_Action]: http://my.oschina.net/u/242041/blog/204312