/**
     * 从Manifest中获取meta-data值
     * @param context
     * @param key
     * @return
     */
    public static String getMetaData(Context context,String key) {
        String value = null;
        try {
            ApplicationInfo appInfo = context.getPackageManager().getApplicationInfo(
                    context.getPackageName(), PackageManager.GET_META_DATA);
            value = appInfo.metaData.getString(key);
        } catch (PackageManager.NameNotFoundException e) {
            e.printStackTrace();
        }
        if (value==null) value="";
        return value;
    }