如何为跨类Volley方法调用创建正确的Volley监听器

Question

我的目标是用一种非常简洁、模块化的方式从另一个类调用凌空：

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

但是我很难让侦听器部分工作，以便能够访问来自以下方法的结果数据

newListener.getResponse();

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);
}

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;
            }
        };
    }
}

Answer 1

对于您的需求，我建议您参考我的以下解决方案，希望它清晰而有帮助：

首先是接口：

public interface VolleyResponseListener {
    void onError(String message);

    void onResponse(Object response);
}

然后在帮助器类（我将其命名为volleyUtils类）中：

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);
}

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

        }

        @Override
        public void onResponse(Object response) {

        }
    });

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