用android volley发出两个请求

Question

我需要使用不同的参数，响应和带有齐射的参数发出两个请求。以下是我的代码

private void LoadFirst() {
        pDialog = new ProgressDialog(getActivity());

        // Showing progress dialog before making http request
        pDialog.setMessage("Loading...");
        pDialog.show();
        final StringRequest userReq = new StringRequest(Method.POST,
                AppConfig.URL_REGISTER, jsonSubjectListener, errorSubjectListener) {

            @Override
            protected Map<String, String> getParams() {
                // Posting params to register url
                Map<String, String> params = new HashMap<String, String>();
                params.put("tag", "retrieveFirst");
                return params;
            }

        };
        AppController.getInstance().addToRequestQueue(userReq);
    }
}

    private void LoadSecond(final String user_type) {
    // Session manager
    session = new SessionManager(getActivity().getApplicationContext());

    // initialising progress dialog
    pDialog = new ProgressDialog(getActivity());

    // Showing progress dialog before making http request
    pDialog.setMessage("Loading...");
    pDialog.show();

    StringRequest userReq = new StringRequest(Method.POST,
            AppConfig.URL_REGISTER, jsonListener, errorListener) {

        @Override
        protected Map<String, String> getParams() {
            // Posting params to register url
            Map<String, String> params = new HashMap<String, String>();

            params.put("tag", "retrieveSecond");

            params.put("user_type", user_type);
            return params;
        }

    };
    AppController.getInstance().addToRequestQueue(userReq);
}

然后我在片段的onActivityCreated下调用了这两个函数。但它无限期地继续加载。我在RequestFuture上阅读了一些内容但我无法看到它如何帮助我使用两个不同的参数，errorListeners和ResponseListeners。感谢