Anroid Receiver

在Android中，广播（broadcast）是非常有用的功能。通过广播可以通知其他广播接受这某个事件发生了。比如电源不足，信号不好等。

下面我做了一个简单的demo，首先看看activity

package
 com.android.broadcasttest;

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 {
    public
 
static
 
final
 String NEW_LIFEFORM_DETECTED =
        "com.android.broadcasttest.NEW_LIFEFORM"
;

    /** Called when the activity is first created. */
    @Override
    public
 
void
 onCreate(Bundle savedInstanceState) {
        super
.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        Button btn0 = (Button)findViewById(R.id.btn0);
        btn0.setOnClickListener(new
 OnClickListener() {
            public
 
void
 onClick(View v) {
                Intent it = new
 Intent(NEW_LIFEFORM_DETECTED);
                sendBroadcast(it);
            }
        });
    }
}

在这个activity中生成了一个按钮，当按下按钮的时候通过sendBroadcast()发送一个广播。

我们再看看广播接收者代码：

package
 com.android.broadcasttest;

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

public
 
class
 MyBroadcastReceiver 
extends
 BroadcastReceiver {
    public
 
static
 
final
 String BURN =
        "com.paad.alien.action.BURN_IT_WITH_FIRE"
;

    public
 MyBroadcastReceiver () {
        Log.v("BROADCAST_TAG"
, 
"myBroadCast"
);
    }
    @Override
    public
 
void
 onReceive(Context context, Intent intent) {
        // TODO Auto-generated method stub
        Toast.makeText(context, "成功接收广播："
, Toast.LENGTH_LONG).show();
    }

}

在onReceive()中实现了当接收到广播所做的动作。

我们还需要在AndroidManifest.xml中注册该receiver

<?
xml
 
version
=
"1.0"
 
encoding
=
"utf-8"
?>
<
manifest
 
xmlns:android
=
"http://schemas.android.com/apk/res/android"
      package
=
"com.android.broadcasttest"
      android:versionCode
=
"1"
      android:versionName
=
"1.0"
>
    <
application
 
android:icon
=
"@drawable/icon"
 
android:label
=
"@string/app_name"
>
        <
activity
 
android:name
=
".BroadcastTest"
                  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
=
"com.android.broadcasttest.NEW_LIFEFORM"
 
/>
            </
intent-filter
>
        </
receiver
>
    </
application
>
    <
uses-sdk
 
android:minSdkVersion
=
"8"
 
/>
</
manifest
>

在receiver的action中定义了该receiver能够接受的广播。