一、前言

        在Android的开发中，我们的程序需要得到网络状态变化、电池状态、屏幕状态、电池、系统启动完成、U盘等外设接入状态、apk安装等这些信息，除了主动去找到这些节点的信息，还可以通过安卓的广播机制被动去得到。

        Android广播机制包含三个基本要素：广播(Broadcast) - 用于发送广播，广播接收器(BroadcastReceiver) - 用于接收广播，关心内容(Intent)-用于保存广播相关信息的媒介。广播是一种广泛运用的在应用程序之间传输信息的机制。而接收器是对发送出来的广播进行过滤接受并响应的一类组件。

        要随时注意安卓的版本，比如安卓8及以上要得到apk安装信息只能通过动态注册的方式。

二、静态注册

        静态注册需要在AndroidManifest.xml文件中添加标签，以获取媒体信息为例：

<receiver android:name="com.tbbpower.android.USBReceiver"><intent-filter><action android:name="android.intent.action.MEDIA_MOUNTED"/><action android:name="android.intent.action.MEDIA_UNMOUNTED"/><data android:scheme="file"/></intent-filter>
</receiver>

        这里声明了接收器的java类，关心的广播内容，然后我们新建一个java类，继承BroadcastReceiver，在onReceive函数中，一旦发生MEDIA_MOUNTED和MEDIA_UNMOUNTED事件，这里就会被动得到广播，下面是部分实例代码：

public class USBReceiver extends BroadcastReceiver {@Overridepublic void onReceive(Context context, Intent intent){Log.d(TAG, "enter USBReceiver onReceive: ");try{String action = intent.getAction();if (action != null){String path=intent.getData().getPath();if(action.equals(Intent.ACTION_MEDIA_MOUNTED))//插入handleMediaStateChange(MediaState.MEDIA_MOUNTED,intent.getData().getPath());else if(action.equals(Intent.ACTION_MEDIA_UNMOUNTED))//拔出handleMediaStateChange(MediaState.MEDIA_UNMOUNTED,intent.getData().getPath());else if(action.equals(Intent.ACTION_MEDIA_EJECT))//handleMediaStateChange(MediaState.MEDIA_EJECT,intent.getData().getPath());else if(action.equals(Intent.ACTION_MEDIA_BAD_REMOVAL))//handleMediaStateChange(MediaState.MEDIA_BAD_REMOVAL,intent.getData().getPath());}}catch (Exception ex){Log.d(TAG, "onReceive-failed "+ex.getMessage());}
}

三、动态注册

        动态注册原理是一样的，我们先创建一个java程序，该类中，我们通过一个静态函数进行注册，实例化BroadcastReceiver，然后一样是在onReceive中进行处理：

package com.tbbpower.android;public class ReceiverManager {private static final String TAG = "ReceiverManager";private static BroadcastReceiver appReceiver;public static void registerBroadcastReceiver(Context context) {// 创建广播接收器实例appReceiver = new BroadcastReceiver() {@Overridepublic void onReceive(Context context, Intent intent) {Log.d(TAG, "enter APPReceiver onReceive : ");try{String action = intent.getAction();if (action != null){if (action.equals(Intent.ACTION_PACKAGE_REPLACED)) {String packageName = intent.getData().getSchemeSpecificPart();Log.d(TAG,"ACTION_PACKAGE_REPLACED:"+packageName);Intent intent1 = context.getPackageManager().getLaunchIntentForPackage(packageName);intent1.setPackage(null);context.startActivity(intent1);}if (action.equals(Intent.ACTION_PACKAGE_ADDED)) {String packageName = intent.getData().getSchemeSpecificPart();Log.d(TAG, "ACTION_PACKAGE_ADDED:" + packageName);}if (action.equals(Intent.ACTION_PACKAGE_REMOVED)) {String packageName = intent.getData().getSchemeSpecificPart();Log.d(TAG,"ACTION_PACKAGE_REMOVED:"+packageName);}}}catch (Exception ex){Log.d(TAG, "onReceive-failed "+ex.getMessage());}}};// 创建意图过滤器并添加行为IntentFilter filter = new IntentFilter();filter.addAction(Intent.ACTION_PACKAGE_ADDED);filter.addAction(Intent.ACTION_PACKAGE_REMOVED);filter.addAction(Intent.ACTION_PACKAGE_REPLACED);filter.addDataScheme("package");// 注册广播接收器context.registerReceiver(appReceiver, filter);}public static void unregisterPackageBroadcastReceiver(Context context) {// 在合适的时候注销广播接收器，以避免内存泄漏if (appReceiver != null) {context.unregisterReceiver(appReceiver);appReceiver = null;}}
}

        在Qt层，我们调用该静态函数即可：

QAndroidJniObject activity = QtAndroid::androidActivity();
if (activity.isValid())
{QAndroidJniObject::callStaticMethod<void>("com/tbbpower/android/ReceiverManager","registerBroadcastReceiver","(Landroid/content/Context;)V",activity.object<jobject>());
}