6.Android BroadcastReceiver

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前面分别讨论了Activity和Service，这篇就介绍Android BroadCastReceiver，BroadCast是应用程序间通信的手段。BroadCastReceiver也是跟Intent紧密相连的，动态/静态注册了BroadCastReceiver之后，使用sendBroadcast把Intent发送之后，系统会自动把符合条件的BroadCastReceiver启动，跟嵌入式系统的中断类似。

本文主要演示了如何动态/静态注册BroadCastReceiver，向系统索取电量信息，以及枚举信息的字段。本文运行截图如下：

testBroadCastReceiver

动态注册BroadcastReceiver

上图是发送Intent至内部动态注册的BroadcastReceiver，接收到之后显示消息名称。动态注册BroadcastReceiver用到registerReceiver()。

静态注册BroadcastReceiver

上图是发送Intent至内部静态注册的BroadcastReceiver，接收到之后显示消息名称。静态注册比动态注册麻烦点，先新建一个类继承BroadcastReceiver，然后到AndroidManifest.xml 添加：

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<receiver android:name="clsReceiver2">
    <intent-filter>
        <action android:name="com.testBroadcastReceiver.Internal_2" />
    </intent-filter>
</receiver>

第一个name是类名，第二个是action的名称。

Log

上图是枚举Intent消息的字段，这个功能比较适合懒人，把收到的Intent消息的字段全部分解了，再看看哪个需要的，懒得记住。实现这部分的代码如下：

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// 当未知Intent包含的内容，则需要通过以下方法来列举
Bundle b=intent.getExtras();
Object[] lstName=b.keySet().toArray();
for(int i=0; i < lstName.length; i++)
{
    String keyName=lstName[i].toString();
    Log.e(keyName,String.valueOf(b.get(keyName)));
}

main.xml

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<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <Button
        android:id="@+id/Button01"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="发送至内部动态注册的BroadcastReceiver"
        />
    <Button
        android:id="@+id/Button02"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="发送至内部静态注册BroadcastReceiver"
        />
    <Button
        android:id="@+id/Button03"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="发送至系统BroadcastReceiver"
        />
</LinearLayout>

testBroadcastReceiver.java

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package com.testBroadcastReceiver;
 
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
 
public class testBroadcastReceiver extends Activity {
    Button btnInternal1, btnInternal2, btnSystem;
    static final String INTENAL_ACTION_1 ="com.testBroadcastReceiver.Internal_1";
    static final String INTENAL_ACTION_2 ="com.testBroadcastReceiver.Internal_2";
    static final String INTENAL_ACTION_3 ="com.testBroadcastReceiver.Internal_3";
 
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        btnInternal1 = (Button) this.findViewById(R.id.Button01);
        btnInternal1.setOnClickListener(new ClickEvent());
        btnInternal2 = (Button) this.findViewById(R.id.Button02);
        btnInternal2.setOnClickListener(new ClickEvent());
        btnSystem = (Button) this.findViewById(R.id.Button03);
        btnSystem.setOnClickListener(new ClickEvent());
        // 动态注册广播消息
        registerReceiver(bcrIntenal1, new IntentFilter(INTENAL_ACTION_1));
    }
 
    class ClickEvent implements View.OnClickListener {
 
        @Override
        public void onClick(View v) {
            if (v == btnInternal1)// 给动态注册的BroadcastReceiver发送数据
            {
                Intent intent = new Intent(INTENAL_ACTION_1);
                sendBroadcast(intent);
            } else if (v == btnInternal2)// 给静态注册的BroadcastReceiver发送数据
            {
                Intent intent = new Intent(INTENAL_ACTION_2);
                sendBroadcast(intent);
            } else if (v == btnSystem)// 动态注册 接收2组信息的BroadcastReceiver
            {
                IntentFilter filter = new IntentFilter();//
                filter.addAction(Intent.ACTION_BATTERY_CHANGED);// 系统电量检测信息
                filter.addAction(INTENAL_ACTION_3);// 第三组自定义消息
                registerReceiver(batInfoReceiver, filter);
 
                Intent intent = new Intent(INTENAL_ACTION_3);
                intent.putExtra("Name", "hellogv");
                intent.putExtra("Blog", "http://blog.csdn.net/hellogv");
                sendBroadcast(intent);// 传递过去
            }
        }
 
    }
 
    /*
     * 接收动态注册广播的BroadcastReceiver
     */
    private BroadcastReceiver bcrIntenal1 = new BroadcastReceiver() {
 
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            Toast.makeText(context, "动态:" + action, 1000).show();
        }
    };
 
    private BroadcastReceiver batInfoReceiver = new BroadcastReceiver() {
 
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            // 如果捕捉到的action是ACTION_BATTERY_CHANGED
            if (Intent.ACTION_BATTERY_CHANGED.equals(action)) {
                // 当未知Intent包含的内容，则需要通过以下方法来列举
                Bundle b = intent.getExtras();
                Object[] lstName = b.keySet().toArray();
 
                for (int i = 0; i < lstName.length; i++) {
                    String keyName = lstName[i].toString();
                    Log.e(keyName, String.valueOf(b.get(keyName)));
                }
            }
            // 如果捕捉到的action是INTENAL_ACTION_3
            if (INTENAL_ACTION_3.equals(action)) {
                // 当未知Intent包含的内容，则需要通过以下方法来列举
                Bundle b = intent.getExtras();
                Object[] lstName = b.keySet().toArray();
 
                for (int i = 0; i < lstName.length; i++) {
                    String keyName = lstName[i].toString();
                    Log.e(keyName, b.getString(keyName));
                }
            }
        }
    };
}

clsReceiver2.java

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package com.testBroadcastReceiver;
 
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;
 
/**
 * 接收静态注册广播的BroadcastReceiver， step1:要到AndroidManifest.xml这里注册消息
 * <receiver android:name="clsReceiver2">
            <intent-filter>
                <action
                    android:name="com.testBroadcastReceiver.Internal_2"/>
            </intent-filter>
        </receiver>
 * step2:定义消息的字符串
 * step3:通过Intent传递消息来驱使BroadcastReceiver触发
 */
public class clsReceiver2 extends BroadcastReceiver{
    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        Toast.makeText(context, "静态:"+action, 1000).show();
         
    }
}