监听应用是否回到桌面

网上可能会有一种不全面的实现方法：通过监听控件的生命周期，但是一旦app是被其它的应用遮挡，而不是真正回到桌面，这个是无法判断的。

参照资料：https://blog.csdn.net/wenzhi20102321/article/details/78604136

定义广播类

public class HomeWatcherReceiver extends BroadcastReceiver {
    private static final String LOG_TAG = " TAG HomeReceiver";

    private static final String SYSTEM_DIALOG_REASON_KEY = "reason";
    //action内的某些reason
    private static final String SYSTEM_DIALOG_REASON_RECENT_APPS = "recentapps";//home键旁边的最近程序列表键
    private static final String SYSTEM_DIALOG_REASON_HOME_KEY = "homekey";//按下home键
    private static final String SYSTEM_DIALOG_REASON_LOCK = "lock";//锁屏键
    private static final String SYSTEM_DIALOG_REASON_ASSIST = "assist";//某些三星手机的程序列表键

    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
//        App app = (App) context.getApplicationContext();
        Logger.e(LOG_TAG, "onReceive: action: " + action);
        if (action.equals(Intent.ACTION_CLOSE_SYSTEM_DIALOGS)) {//Action
            // android.intent.action.CLOSE_SYSTEM_DIALOGS
            String reason = intent.getStringExtra(SYSTEM_DIALOG_REASON_KEY);
            Logger.e(LOG_TAG, "reason: " + reason);

            if (SYSTEM_DIALOG_REASON_HOME_KEY.equals(reason)) { // 短按Home键
                //可以在这里实现关闭程序操作。。。
                Logger.e(LOG_TAG, "homekey");
                List<HomeWatchHelper.OnHomeKeyPressedListener> homeKeyPressedListeners = HomeWatchHelper.getInstance().getHomeKeyPressedListeners();
                boolean background = GlobalMagicJavaUtil.isBackground(context);
                if(background == false){
                    for (HomeWatchHelper.OnHomeKeyPressedListener item: homeKeyPressedListeners){
                        item.onHomeKeyPressed();
                    }
                }else{
                    Logger.e(LOG_TAG, "应用已经在后台了，homekey就不回调了。");
                }
            } else if (SYSTEM_DIALOG_REASON_RECENT_APPS.equals(reason)) {//Home键旁边的显示最近的程序的按钮
                // 长按Home键 或者 activity切换键
                Logger.e(LOG_TAG, "long press home key or activity switch");
            } else if (SYSTEM_DIALOG_REASON_LOCK.equals(reason)) {  // 锁屏，似乎是没有反应，监听Intent.ACTION_SCREEN_OFF这个Action才有用
                Logger.e(LOG_TAG, "lock");
            } else if (SYSTEM_DIALOG_REASON_ASSIST.equals(reason)) {   // samsung 长按Home键
                Logger.e(LOG_TAG, "assist");
            }

        }
    }
    
}

注册与解注册广播

 //注册广播接收者，监听Home键
    private void registerHomeKeyReceiver(Context context) {
        Logger.e(TAG, "registerHomeKeyReceiver");
        mHomeKeyReceiver = new HomeWatcherReceiver();
        IntentFilter homeFilter = new IntentFilter(Intent.ACTION_CLOSE_SYSTEM_DIALOGS);
        context.registerReceiver(mHomeKeyReceiver, homeFilter);
    }

    //取消监听广播接收者
    private void unregisterHomeKeyReceiver(Context context) {
        Logger.e(TAG, "unregisterHomeKeyReceiver");
        if (null != mHomeKeyReceiver) {
            context.unregisterReceiver(mHomeKeyReceiver);
        }
    }