Broadcast广播

朴灿烈づ我的快乐病毒、 2024-02-17 22:24 3阅读 0赞

注册BroadcastReceiver有两种方法：在AndroidManifest.xml文件中进行注册；在应用程序的代码中进行注册（推荐）。

第一种方法，应用程序退出，系统仍然能匹配到Action，用户体验很不好。

## 1 BroadcastReceiver ##

### 1.1 Broadcast Receiver广播接收器 ###

它和事件处理机制类似，只不过事件处理机制是程序组件级别，而广播事件机制是系统级别的。

BroadcastReceiver对象仅在调用onReceiver()方法时有效，当该方法执行完毕后，系统会销毁该对象。

### 1.2 使用Broadcast Receiver ###

①编写类继承BroadcastReceiver，复写onReceiver()方法

public class MyBroadcastReceiver extends BroadcastReceiver {
    
    	
    	private static final String TAG = "MyBroadcastReceiver";
    
    	@Override
    	public void onReceive(Context arg0, Intent arg1) {
    		Log.i(TAG, "onReceive");
    	}
    
    }

②在AndroidManifest.xml文件中注册BroadcastReceiver

③构建Intent对象，调用sendBroadcast()方法，发送广播

public class MainActivity extends Activity {
    
    	
        protected static final String ACTION = "com.example.broadcast.Action";
    
    	@Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            
            Button broadcastBtn = (Button) findViewById(R.id.startBtn);
            broadcastBtn.setOnClickListener(new Button.OnClickListener() {
    			
    			@Override
    			public void onClick(View v) {
    				Intent intent = new Intent();
    				intent.setAction(ACTION);
    				sendBroadcast(intent);
    			}
    		});
            
        }
    
    }

### 1.3 使用Broadcast发送短信广播 ###

<?xml version="1.0" encoding="utf-8"?>
    <manifest xmlns:android="http://schemas.android.com/apk/res/android"
        package="com.example.broadcast"
        android:versionCode="1"
        android:versionName="1.0" >
    
        <uses-sdk
            android:minSdkVersion="8"
            android:targetSdkVersion="18" />
    	<uses-permission android:name="android.permission.RECEIVE_SMS"/>   
        
        <application
            android:allowBackup="true"
            android:icon="@drawable/ic_launcher"
            android:label="@string/app_name"
            android:theme="@style/AppTheme" >
            <activity
                android:name="com.example.broadcast.MainActivity"
                android:label="@string/app_name" >
                <intent-filter>
                    <action android:name="android.intent.action.MAIN" />
    
                    <category android:name="android.intent.category.LAUNCHER" />
                </intent-filter>
            </activity>
            <receiver android:name="com.example.broadcast.MyBroadcastReceiver">
                <intent-filter>
                    <action android:name="android.provider.Telephony.SMS_RECEIVED"/>  
                </intent-filter>
            </receiver>
        </application>
    </manifest>

**BroadcastReceiver.java:**

package com.example.broadcast;
    
    import android.content.BroadcastReceiver;
    import android.content.Context;
    import android.content.Intent;
    import android.os.Bundle;
    import android.telephony.gsm.SmsMessage;
    import android.util.Log;
    
    public class MyBroadcastReceiver extends BroadcastReceiver {
    
    	
    	private static final String TAG = "MyBroadcastReceiver";
    
    	@Override
    	public void onReceive(Context context, Intent intent) {
    		Log.i(TAG, "onReceive");
    		
    		// 接受Intent对象中的数据
    		Bundle bundle = intent.getExtras();
    		// 在Bundle对象中有一个pdus属性，属性值为一个object数组
    		Object[] myOBJpdus = (Object[]) bundle.get("pdus");
    		// 创建一个SmsMessage类型的数组
    		SmsMessage[] messages = new SmsMessage[myOBJpdus.length];
    		Log.i(TAG, messages.length+"");
    		for(int i=0; i<myOBJpdus.length; i++) {
    			// 使用Object数组中的对象创建SmsMessage对象
    			messages[i] = SmsMessage.createFromPdu((byte[])myOBJpdus[i]);
    			// 调用SmsMessage对象的getDisppalyMessageBody()方法，就可以得到消息的内容
    			Log.i(TAG, messages[i].getDisplayMessageBody());
    		}
    	}
    
    }

## 2 在应用程序代码中进行注册实现BroadcastReceiver ##

注册BroadcastReceiver：registerReceiver()

取消注册BroadcastReceiver：unregisterReceiver()

![Center][]

**Activity中的实现：(**其他部分与上面类似，**androidManifest.xml中不再需要注册)**

((Button)findViewById(R.id.registerBtn)).setOnClickListener(new Button.OnClickListener() {
    	@Override
    	public void onClick(View v) {
    		if(myReceiver==null) {
    			myReceiver = new MyBroadcastReceiver();
    		}
    		IntentFilter filter = new IntentFilter();
    		filter.addAction(ACTION);
    		registerReceiver(myReceiver, filter);
    		}
    });
    ((Button)findViewById(R.id.unregisterBtn)).setOnClickListener(new Button.OnClickListener() {
    	@Override
    	public void onClick(View v) {
    		if(myReceiver!=null) {
    			unregisterReceiver(myReceiver);
    		}
    	}
    });

[Center]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/e9925f88ff59432c86a92470e8a10370.png