当 error.networkResponse 为空时，Android Volley 中的 Http 状态代码 [英] Http Status Code in Android Volley when error.networkResponse is null

问题描述

我在 Android 平台上使用 Google Volley.我遇到了一个问题，其中 onErrorResponse 中的 error 参数返回一个 null networkResponse对于我使用的 RESTful API，我需要确定 Http 状态代码，它通常以 401 (SC_UNAUTHORIZED) 或 500 (SC_INTERNAL_SERVER_ERROR) 的形式出现，我偶尔可以通过以下方式检查:

I am using Google Volley on the Android platform. I am having a problem in which the error parameter in onErrorResponse is returning a null networkResponse For the RESTful API I am using, I need to determine the Http Status Code which is often arriving as 401 (SC_UNAUTHORIZED) or 500 (SC_INTERNAL_SERVER_ERROR), and I can occasionally check via:

final int httpStatusCode = error.networkResponse.statusCode;
if(networkResponse == HttpStatus.SC_UNAUTHORIZED) {
    // Http status code 401: Unauthorized.
}

这会抛出一个 NullPointerException 因为 networkResponse 为空.

This throws a NullPointerException because networkResponse is null.

如何判断onErrorResponse函数中的Http状态码?

How can I determine the Http Status Code in the function onErrorResponse?

或者，如何确保 error.networkResponse 在 onErrorResponse 中不为空?

Or, how can I ensure error.networkResponse is non-null in onErrorResponse?

推荐答案

401 Not Supported by Volley

事实证明，在不修改 Google Volley 代码的情况下无法保证 error.networkResponse 为非空，因为 Volley 中的一个错误会引发 Http 状态代码 401 的异常 NoConnectionError (HttpStatus.SC_UNAUTHORIZED) 在 BasicNetwork.java (134) 中设置 networkResponse 的值.

401 Not Supported by Volley

It turns out that it is impossible to guarantee that error.networkResponse is non-null without modifying Google Volley code because of a bug in Volley that throws the Exception NoConnectionError for Http Status Code 401 (HttpStatus.SC_UNAUTHORIZED) in BasicNetwork.java (134) prior to setting the value of networkResponse.

在这种情况下，我们的解决方案不是修复 Volley 代码，而是修改 Web 服务 API 以针对相关特定情况发送 Http 错误代码 403 (HttpStatus.SC_FORBIDDEN).

Instead of fixing the Volley code, our solution in this case was to modify the Web Service API to send Http Error Code 403 (HttpStatus.SC_FORBIDDEN) for the particular case in question.

对于这个 Http 状态码，error.networkResponse 的值在 Volley 错误处理程序中是非空的:public void onErrorResponse(VolleyError error).并且，error.networkResponse.httpStatusCode 正确返回 HttpStatus.SC_FORBIDDEN.

For this Http Status Code, the value of error.networkResponse is non-null in the Volley error handler: public void onErrorResponse(VolleyError error). And, error.networkResponse.httpStatusCode correctly returns HttpStatus.SC_FORBIDDEN.

Rperryng 提出的扩展 Request 类的建议可能已经提供了一个解决方案，并且是一个创造性和极好的想法.非常感谢您提供的详细示例.我发现我们案例的最佳解决方案是使用变通方法，因为我们很幸运能够控制 Web 服务 API.

Rperryng's suggestion of extending the Request<T> class may have provided a solution, and is a creative and excellent idea. Thank you very much for the detailed example. I found the optimal solution for our case is to use the work-around because we are fortunate enough to have control of the web services API.

如果我无法在服务器上进行简单的更改，我可能会选择在 BasicNetwork.java 中的一个位置修复 Volley 代码.

I might opt for fixing the Volley code in one location within BasicNetwork.java if I did not have access to making a simple change at the server.

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