调用系统DownloadManager IllegalArgumentException

调用 系统DownloadManager 是抛出如下异常：

IllegalArgumentException: Unknown URL content://downloads/my_downloads

是因为系统的下载服务被停止了：

    /**     * 检查系统下载服务是否可用     * @return     */    public static boolean checkDownloadManagerEnable() {        try {            ApplicationInfo ai = MaibuWatchApplication.getContext().getPackageManager().getApplicationInfo("com.android.providers.downloads",0);            return ai.enabled;        } catch (PackageManager.NameNotFoundException e) {            // TODO Auto-generated catch block            e.printStackTrace();        }        return false;    }

若关闭，跳转到应用详情页，让用户打开：

       if (!NetUtils.checkDownloadManagerEnable()){//下载服务被关闭            Toast.makeText(context,"下载管理器被关闭，请打开",Toast.LENGTH_SHORT).show();           dissmisInstallDialog();           final AlertDialogFragment alertDialogFragment=AlertDialogFragment.newInstance("下载错误","下载管理器被停止，请启动","确定");           alertDialogFragment.setOnConfirmListener(new View.OnClickListener() {               @Override               public void onClick(View v) {                   Intent intent = new Intent(Settings.ACTION_APPLICATION_DETAILS_SETTINGS);                   Uri uri = Uri.fromParts("package", "com.android.providers.downloads", null);                   intent.setData(uri);                   context.startActivity(intent);                   alertDialogFragment.dismiss();               }           });           alertDialogFragment.show(context.getFragmentManager(),"open");           return;       }