Broadcast Receiver（广播接收器）

Braodcast Receiver顾名思义就是广播接收器，它和时间处理机制类似，但是事件处理机制是程序组件级别的（比如：按钮的单击事件），而广播事件处理机制是系统级别的。我们可以用Intent来启动一个组件，也可以用sendBroadcast()方法发起一个系统级别的事件广播来传递消息。我们同样可以在自己的应用程序中实现Broadcast Receiver来监听和响应广播的Intent。

事件的广播通过创建Intent对象并调用sendBroadcast()方法将广播发出。事件的接受是通过定义一个继承BroadcastReceiver的类来实现的，继承该类后覆盖其onReceive()方法，在该方法中响应时间。

下面是android系统中定义了很多标准的Broadcast Action来响应系统的广播事件。

①ACTION_TIME_CHANGED（时间改变时触发）

②ACTION_BOOT_COMPLETED(系统启动完成后触发)--比如有些程序开机后启动就是用这种方式来实现的

③ACTION_PACKAGE_ADDED（添加包时触发）

④ACTION_BATTERY_CHANGED（电量低时触发）

详细：标准广播ACTION常量

 

常量名称	常量值	意义
ACTION_BOOT_COMPLETED	android.intent.action.BOOT_COMPLETED	系统启动完成
ACTION_TIME_CHANGED	android.intent.action.ACTION_TIME_CHANGED	时间改变
ACITON_DATE_CHANGED	android.intent.action.ACTION_DATE_CHANGED	日期改变
ACTION_TIMEZONE_CHANGED	android.intent.action.ACTION_TIMEZONE_CHANGED	时区该表
ACTION_BATTERY_LOW	android.intent.action.ACTION_BATTERY_LOW	电量低
ACTION_MEDIA_EJECT	android.intent.action.ACTION_MEDIA_EJECT	插入或拔出外部媒体
ACTION_MEDIA_BUTTON	android.intent.action.ACTION_MEDIA_BUTTON	按下媒体按钮
ACTION_PACKAGE_ADDED	android.intent.action.ACTION_PACKAGE_ADDED	添加包
ACTION_PACKAGE_REMOVED	android.intent.action.ACTION_PACKAGE_REMOVED	删除包

 

在这里，要练习3个内容

①自定义Broadcast Receiver

②Notification和NotificationManager的使用

③AlarmManager的使用

 

1、首先看一个自定义的广播事件的例子

package org.hualang.broadcast;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class BroadCastTest extends Activity {
    /** Called when the activity is first created. */
    private static final String MY_ACTION="org.hualang.broadcast.action.MY_ACTION";
    private Button btn;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        btn=(Button)findViewById(R.id.button);
        btn.setOnClickListener(new OnClickListener()
        {

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                Intent intent=new Intent();
                intent.setAction(MY_ACTION);
                intent.putExtra("msg", "同志们好！同志们辛苦啦！");
                sendBroadcast(intent);
            }

        });
    }
}

 

MyReceiver.java

package org.hualang.broadcast;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.widget.Toast;

public class MyReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context arg0, Intent arg1) {
        // TODO Auto-generated method stub
        String msg=arg1.getStringExtra("msg");
        Toast.makeText(arg0, msg, Toast.LENGTH_LONG).show();
    }

}

 

注意：在AndroidManifest.xml文件中注册

<receiver android:name="MyReceiver">
            <intent-filter>
                <action android:name="org.hualang.broadcast.action.MY_ACTION"/>
            </intent-filter>
        </receiver>

 

 

我们还可以在AndroidManifest.xml文件中注销一个广播接收器，一般在Activity.onResume()方法中使用Context.registerReceiver()方法来注册一个广播接收器，在Activity.onPause()中使用unregisterReceiver(r)方法注销一个广播接收器，例如：

//实例化intent过滤器

IntentFilter filter = new IntentFilte()；

//实例化Receiver

MyReceiver r = new Receiver();

//注册Receiver

registerReceiver(r,filter);

 

为了注销一个BroadcastReceiver，应使用Context.unregisterReceiver方法，传入一个BroadcastReceiver实例

//注销

unregisterReceiver(r);

 

2、下面的是Notification的例子，比如手机来短信的时候，会在屏幕最上边有一个通知，那个就是Notification

DisplayActivity.java

package org.hualang.notify;

import android.app.Activity;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class DisplayActivity extends Activity {
    private Button cancelbtn;
    private Notification n;
    private NotificationManager nm;
    private static final int ID=1;
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main2);
        cancelbtn = (Button)findViewById(R.id.button2);
        String service = NOTIFICATION_SERVICE;
        nm = (NotificationManager)getSystemService(service);

        n = new Notification();
        int icon = n.icon =R.drawable.icon;
        String tickerText = "喜欢HTC的样子，喜欢defy的配置";
        long when = System.currentTimeMillis();
        n.icon = icon;
        n.tickerText = tickerText;
        n.when = when;

        Intent intent = new Intent(this,NotifyTest2.class);
        PendingIntent pi = PendingIntent.getActivity(this, 0 , intent , 0);
        n.setLatestEventInfo(this, "My Title", "My Content", pi);
        nm.notify(ID, n);
        cancelbtn.setOnClickListener(cancelListener);
    }
    private OnClickListener cancelListener=new OnClickListener()
    {
        public void onClick(View v)
        {
            nm.cancel(ID);
        }
    };
}

 MyReceiver.java

package org.hualang.notify;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;

public class MyReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        // TODO Auto-generated method stub
        Intent i=new Intent();
        i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        i.setClass(context,DisplayActivity.class);
        context.startActivity(i);
    }

}

 

NotifyTest2.java

package org.hualang.notify;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class NotifyTest2 extends Activity {
    /** Called when the activity is first created. */
    private Button btn;
    private static final String MY_ACTION="org.hualang.notify.aciton.MY_ACITON";
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        btn=(Button)findViewById(R.id.button);
        btn.setOnClickListener(listener);
    }
    private OnClickListener listener=new OnClickListener()
    {
        public void onClick(View v)
        {
            Intent intent=new Intent();
            intent.setAction(MY_ACTION);
            sendBroadcast(intent);
        }
    };
}

 

注册AndroidManifest.xml

<receiver android:name="MyReceiver">
            <intent-filter>
                <action android:name="org.hualang.notify.aciton.MY_ACITON"/>
            </intent-filter>
        </receiver>
        <activity android:name="DisplayActivity">
        </activity>

 

运行结果如下：

 

3、下面是AlarmManager的例子，它是一个闹钟，感兴趣的朋友可以自己写一个小闹钟

AlarmManager常用的属性和方法

 

属性或方法名称	说明
ELAPSED_REALTIME	设置闹钟时间，从系统启动开始
ELAPSED_REALTIME_WAKEUP	设置闹钟时间，从系统启动开始，如火设备休眠则唤醒
INTERVAL_DAY	设置闹钟时间，间隔一天
INTERVAL_FIFTEEN_MINUTES	间隔15分钟
INTERVAL_HALF_DAY	间隔半天
INTERVAL_HALF_HOUR	间隔半小时
INTERVAL_HOUR	间隔1小时
RTC	设置闹钟时间，从系统当前时间开始(System.currentTimeMillis())
RTC_WAKEUP	设置闹钟时间，从系统当前时间开始，设备休眠则唤醒
set(int type,long tiggerAtTime,PendingIntent operation)	设置在某个时间执行闹钟
setRepeating(int type,long triggerAtTiem,long interval,PendingIntent operation)	设置在某个时间重复执行闹钟
setInexactRepeating(int type,long triggerAtTiem,long interval,PendingIntent operation)	是指在某个时间重复执行闹钟，但不是间隔固定时间

 

AlarmTest.java

package org.hualang.alarm;

import android.app.Activity;
import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class AlarmTest extends Activity {
    /** Called when the activity is first created. */
    private Button btn1,btn2;
    private static final String BC_ACTION="org.hualang.alarm.action.BC_ACTION";
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        btn1 = (Button)findViewById(R.id.button1);
        btn2 = (Button)findViewById(R.id.button2);

        final AlarmManager am = (AlarmManager)getSystemService(ALARM_SERVICE);
        Intent intent = new Intent();
        intent.setAction(BC_ACTION);
        intent.putExtra("msg", "你该起床了");
        final PendingIntent pi = PendingIntent.getBroadcast(AlarmTest.this, 0, intent, 0);
        final long time = System.currentTimeMillis();


        btn1.setOnClickListener(new OnClickListener()
        {
            public void onClick(View v)
            {

                am.setRepeating(AlarmManager.RTC_WAKEUP, time, 5*1000, pi);
            }
        });
        btn2.setOnClickListener(new OnClickListener()
        {
            public void onClick(View v)
            {
                am.cancel(pi);
            }
        });
    }
}

 

MyReceiver.java

package org.hualang.alarm;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.util.Log;
import android.widget.Toast;

public class MyReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        // TODO Auto-generated method stub
        String msg=intent.getStringExtra("msg");
        Log.v("SERVICE","QIAN----------------------");
        Toast.makeText(context, msg, Toast.LENGTH_LONG).show();
        Log.v("SERVICE", "HOU-----------------------");
    }

}

 

注册AndroidManifest.xml

<receiver android:name="MyReceiver">
            <intent-filter>
                <action android:name="org.hualang.alarm.action.BC_ACTION"/>
            </intent-filter>
        </receiver>

 运行结果：

 

 点击设置闹钟后，会每隔5秒弹出一个Toast，点击取消闹钟就不会弹出了

来自：http://hualang.iteye.com/blog/1003374