//檢查某個應用是否安裝
    public static boolean checkAPP(Context context, String packageName) {
        if (packageName == null || "".equals(packageName))
            return false;
        try {
            ApplicationInfo info = context.getPackageManager()
                    .getApplicationInfo(packageName,
                            PackageManager.GET_UNINSTALLED_PACKAGES);
            return true;
        } catch (NameNotFoundException e) {
            return false;
        }
    }