如何为跨类 Volley 方法调用创建合适的 Volley Listener [英] How to create a proper Volley Listener for cross class Volley method calling

问题描述

我的目标是从另一个类中调用 Volley，一种非常简洁、模块化的方式，即:

I aim to call Volley from another class in, a very succinct, modular way ie:

            VolleyListener newListener = new VolleyListener();
            VolleySingleton.getsInstance().somePostRequestReturningString(getApplicationContext(), newListener);
            JSONObject data = newListener.getResponse();

但是在让侦听器部分工作以便能够从诸如

But am having allot of trouble getting the listener portion to work so as to be able to access the resulting data from a method such as

newListener.getResponse();

这个站点上有几个问题大致概述了如何从另一个类设置截击呼叫，例如:Android Volley - 如何隔离另一个类中的请求.我已经成功地使方法调用起作用，但现在将该数据放入当前类以供使用却造成了麻烦.

There are a few questions on this site that generally outline how to set up a volley call from another class, such as: Android Volley - How to isolate requests in another class. I have had success getting the method call to work, but to now get that data into the present class for usage has caused trouble.

我的 VolleySingleton 类中的操作为:

I have the action within my VolleySingleton class as:

public void somePostRequestReturningString(final Context context,final VolleyListener<String> listener) {

        final String URL = "http://httpbin.org/ip";

        JsonObjectRequest set = new JsonObjectRequest(Request.Method.GET, URL, ((String) null),
                new Response.Listener<JSONObject>() {
                    @Override
                    public void onResponse(JSONObject response) {

                        listener.outPut = response.toString();
                        //Toast.makeText(context, response.toString(), Toast.LENGTH_LONG).show();
                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        Log.d("Error.Response", error.toString());
                    }
                }
        );

        mRequestQueue.add(set);
}

在监听器类中:

public class VolleyListener {
    public static String outPut;

    private static Response.Listener<String> createSuccessListener() {
        return new Response.Listener<String>() {
            @Override
            public void onResponse(String response) {
                outPut = response;
            }
        };
    }
}

如何配置它以使其工作并允许从另一个类中进行 Volley 调用和数据检索，尤其是如何正确构建回调?

How can I configure this to work and allow Volley calls and data retrieval from another class, particularly how to build callbacks correctly?

推荐答案

根据你的需求，建议你参考我下面的解决方案，希望对你有帮助:

For your requirement, I suggest you refer to my following solution, hope it's clear and helpful:

首先是界面:

public interface VolleyResponseListener {
    void onError(String message);

    void onResponse(Object response);
}

然后在您的助手类中(我将其命名为 VolleyUtils 类):

Then inside your helper class (I name it VolleyUtils class):

public static void makeJsonObjectRequest(Context context, String url, final VolleyResponseListener listener) {
        JsonObjectRequest jsonObjectRequest = new JsonObjectRequest
                (url, null, new Response.Listener<JSONObject>() {

                @Override
                public void onResponse(JSONObject response) {
                    listener.onResponse(response);
                }
            }, new Response.ErrorListener() {

                @Override
                public void onErrorResponse(VolleyError error) {
                    listener.onError(error.toString());
                }
            }) {

        @Override
        protected Response<JSONObject> parseNetworkResponse(NetworkResponse response) {
            try {
                String jsonString = new String(response.data,
                        HttpHeaderParser.parseCharset(response.headers, PROTOCOL_CHARSET));
                return Response.success(new JSONObject(jsonString),
                        HttpHeaderParser.parseCacheHeaders(response));
            } catch (UnsupportedEncodingException e) {
                return Response.error(new ParseError(e));
            } catch (JSONException je) {
                return Response.error(new ParseError(je));
            }
        }
    };

    // Access the RequestQueue through singleton class.
    VolleySingleton.getInstance(context).addToRequestQueue(jsonObjectRequest);
}

然后，在您的 Activity 类中，您可以像下面这样调用:

Then, inside your Activity classes, you can call like the following:

VolleyUtils.makeJsonObjectRequest(mContext, url, new VolleyResponseListener() {
        @Override
        public void onError(String message) {

        }

        @Override
        public void onResponse(Object response) {

        }
    });

您可以参考以下问题了解更多信息(正如我昨天告诉您的):

You can refer to the following questions for more information (as I told you yesterday):

Android:如何从方法返回异步 JSONObject使用 Volley?

POST 请求 Json 文件传递字符串并等待响应 Volley

Android/Java:如何在方法中延迟返回

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