当响应代码304和200时出现Volley异常错误

Question

在使用Volley库时，我注意到在进行POST时JsonObjectRequest，如果服务器返回的代码304或200没有响应中的数据(response.data)，Volley会将其解释为错误响应，而不是成功。

我设法通过Response<JSONObject> parseNetworkResponse(NetworkResponse response)在类的方法中添加几行代码来解决该问题JsonObjectRequest.java。

@Override
protected Response<JSONObject> parseNetworkResponse(NetworkResponse response) {
    try {
        if (!response.notModified) {// Added for 304 response
            String jsonString = new String(response.data,
                    HttpHeaderParser.parseCharset(response.headers));
            return Response.success(new JSONObject(jsonString),
                    HttpHeaderParser.parseCacheHeaders(response));
        } else // Added for 304 response
            return Response.success(new JSONObject(),HttpHeaderParser.parseCacheHeaders(response));
    } catch (UnsupportedEncodingException e) {
        Log.v("Volley", "UnsupportedEncodingException " + response.statusCode);
        if (response.statusCode == 200)// Added for 200 response
            return Response.success(new JSONObject(), HttpHeaderParser.parseCacheHeaders(response));
        else
            return Response.error(new ParseError(e));
    } catch (JSONException je) {
        Log.v("Volley", "JSONException " + response.statusCode);
        if (response.statusCode == 200)// Added for 200 response
            return Response.success(new JSONObject(),HttpHeaderParser.parseCacheHeaders(response));
        else
            return Response.error(new ParseError(je));
    }
}

这是解决此问题的最佳解决方案吗？

谢谢！

编辑

检查类时，BasicNetwork.java我意识到Volley通过询问是否检查响应是否没有数据httpResponse.getEntity() != null。

// Some responses such as 204s do not have content. We must check.
    if (httpResponse.getEntity() != null) {
        responseContents = entityToBytes(httpResponse.getEntity());         
    } else {// Add 0 byte response as a way of honestly representing a
    // no-content request.
        responseContents = new byte[0];
    }

但是问题仍然是Volley尝试response.data == new byte[0]在parseNetworkResponse方法中使用创建新字符串时发生的JSONException。

Answer 1

Miguel-仅在成功响应后才调用此方法吗？

对于所有状态代码<200或状态代码> 200，Volley调用parseNetworkError（VolleyError
volleyError）而不是parseNetworkResponse（NetworkResponse response）方法。看这里 -

https://android.googlesource.com/platform/frameworks/volley/+/master/src/com/android/volley/toolbox/BasicNetwork.java

行号-118-120

  if (statusCode < 200 || statusCode > 299) {
                throw new IOException();
   }

和相应的捕获块行号-128 -151

catch (IOException e) {
            int statusCode = 0;
            NetworkResponse networkResponse = null;
            if (httpResponse != null) {
                statusCode = httpResponse.getStatusLine().getStatusCode();
            } else {
                throw new NoConnectionError(e);
            }
            VolleyLog.e("Unexpected response code %d for %s", statusCode, request.getUrl());
            if (responseContents != null) {
                networkResponse = new NetworkResponse(statusCode, responseContents,
                        responseHeaders, false);
                if (statusCode == HttpStatus.SC_UNAUTHORIZED ||
                        statusCode == HttpStatus.SC_FORBIDDEN) {
                    attemptRetryOnException("auth",
                            request, new AuthFailureError(networkResponse));
                } else {
                    // TODO: Only throw ServerError for 5xx status codes.
                    throw new ServerError(networkResponse);
                }
            } else {
                throw new NetworkError(networkResponse);
            }
        }

如果要覆盖此行为，可以在BasicNetwork.java-> performRequest方法内添加特定于状态码的实现。

编辑：所以它不是因为状态码而是因为响应为空。好吧，我认为您在实现自定义Request类方面做得正确。Volley随附了一些预定义的流行请求类型，以简化易用性，但您始终可以创建自己的请求。与其基于状态码的实现，不如直接反序列化之前检查以下字符串是否为空-

String jsonString = new String(response.data,
                HttpHeaderParser.parseCharset(response.headers));
if (!jsonString .isEmpty()) {
                 return Response.success(new JSONObject(jsonString),
                HttpHeaderParser.parseCacheHeaders(response));
}
else {
return Response.success(new JSONObject(),
                    HttpHeaderParser.parseCacheHeaders(response));
}

**尚未测试过，但您明白了:)