【Android学习】Android广播机制

原创

易寒

发布于 2021-12-23 13:50:35

4530

发布于 2021-12-23 13:50:35

文章被收录于专栏：Android知识

在Android中实现广播，首先我们要在Manifest.xml文件中配置一个<receiver/>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<intent-filter/>,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：<uses-permission/>,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：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
            package="com.gufengxiachen.broadcast"
            android:versionCode="1"
            android:versionName="1.0">
        <uses-sdk android:minSdkVersion="8" />
        <application android:icon="@drawable/icon" android:label="@string/app_name">
                <activity android:name=".BroadCast"
                                    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=".MyBroadCastReceiver">
<intent-filter>
<action android:name="android.intent.action.EDIT"></action>
</intent-filter>
</receiver>
        </application>
        <uses-permission android:name="android.permission.RECEIVE_SMS"></uses-permission>
</manifest>

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");
}
}

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