在Android中,廣播(broadcast)是非常有用的功能。通過廣播可以通知其他廣播接受這某個事件發生了。比如電源不足,訊號不好等。
下面我做了一個簡單的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);
- }
- });
- }
- }
在這個activity中產生了一個按鈕,當按下按鈕的時候通過sendBroadcast()發送一個廣播。
我們再看看廣播接收者代碼:
- 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, "成功接收廣播:", Toast.LENGTH_LONG).show();
- }
-
- }
在onReceive()中實現了當接收到廣播所做的動作。
我們還需要在AndroidManifest.xml中註冊該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中定義了該receiver能夠接受的廣播。