Android广播机制-BroadcastReceiver详解
2012-11-25 22:25 957 0
Broastcast是应用程序间通信的手段。BroastcastReceiver也是跟Intent紧密相连的，动态/静态注册了BroastcastReceiver之后，使用sendBroadcast把Intent发送之后，系统会自动把符合条件的BroastcastReceiver启动，跟嵌入式系统的中断类似。
本文主要演示了如何静态/动态注册BroastcastReceiver，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：
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()。
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
<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。
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：
//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的代码如下：
<?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>
<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>
<Button android:id="@+id/Button03" android:layout_width="wrap_content"
android:layout_height="wrap_content" android:text="发送至系统BroadcastReceiver"></Button>
</LinearLayout>
testBroadcastReceiver.java的代码如下：
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://www.jcodecraeer.com");
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的代码如下：
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();
}
}
