Question

我有一个正在使用的Owin中间件类。目的是在检测到401、403或405 HTTP状态代码时覆盖响应正文，并用JSON对象替换该正文。到目前为止，这是我的方法：

public override async Task Invoke(IOwinContext context)
        {
            await Next.Invoke(context);

            if (context.Response.StatusCode == 401 || context.Response.StatusCode == 403 || context.Response.StatusCode == 405)
            {

                var owinResponse = context.Response;
                var owinResponseStream = owinResponse.Body;
                var responseBuffer = new MemoryStream();
                owinResponse.Body = responseBuffer;

                string message;

                switch (context.Response.StatusCode)
                {
                    case 401:
                        message = "unauthorized request";
                        break;
                    case 403:
                        message = "forbidden request";
                        break;
                    default:
                        message = "request not allowed";
                        break;
                }
                var newResponse = new ResponseMessage<string>
                {
                    IsError = true,
                    StatusCode = (HttpStatusCode) Enum.Parse(typeof(HttpStatusCode), context.Response.StatusCode.ToString()),
                    Data = null,
                    Message = message
                };

                var customResponseBody = new StringContent(JsonConvert.SerializeObject(newResponse));
                var customResponseStream = await customResponseBody.ReadAsStreamAsync();
                await customResponseStream.CopyToAsync(owinResponseStream);
                owinResponse.ContentType = "application/json";
                owinResponse.ContentLength = customResponseStream.Length;
                owinResponse.StatusCode = 200;
                owinResponse.Body = owinResponseStream;
            }

        }

在大多数情况下，它可以正常工作，但是响应正文被附加到而不是被替换。例如，在401错误的情况下，响应主体为：

{"message":"Authorization has been denied for this request."}
{"IsError":true,"StatusCode":401,"Data":null,"Message":"unauthorized request"}

代替：

{"IsError":true,"StatusCode":401,"Data":null,"Message":"unauthorized request"}

我确定这与我写给响应正文的方式有关，但是到目前为止，没有任何东西可以解决问题。

任何建议将不胜感激。

谢谢

Answer 1

因为您在await Next.Invoke(context);之后写了以下代码

await Next.Invoke(context);

            if (context.Response.StatusCode == 401 || context.Response.StatusCode == 403 || context.Response.StatusCode == 405)
            {

                var owinResponse = context.Response;
                var owinResponseStream = owinResponse.Body;
                var responseBuffer = new MemoryStream();
                owinResponse.Body = responseBuffer;

错了。

下一个代码片段可以根据需要工作：

public override async Task Invoke(IOwinContext context)
        {
            var owinResponse = context.Response;
            var owinResponseStream = owinResponse.Body;
            var responseBuffer = new MemoryStream();
            owinResponse.Body = responseBuffer;

            await Next.Invoke(context);

            if (context.Response.StatusCode == 401 || context.Response.StatusCode == 403 || context.Response.StatusCode == 405)
            {

                string message;

                switch (context.Response.StatusCode)
                {
                    case 401:
                        message = "unauthorized request";
                        break;
                    case 403:
                        message = "forbidden request";
                        break;
                    default:
                        message = "request not allowed";
                        break;
                }
                var newResponse = new ResponseMessage<string>
                {
                    IsError = true,
                    StatusCode = (HttpStatusCode) Enum.Parse(typeof(HttpStatusCode), context.Response.StatusCode.ToString()),
                    Data = null,
                    Message = message
                };

                var customResponseBody = new StringContent(JsonConvert.SerializeObject(newResponse));
                var customResponseStream = await customResponseBody.ReadAsStreamAsync();
                await customResponseStream.CopyToAsync(owinResponseStream);
                owinResponse.ContentType = "application/json";
                owinResponse.ContentLength = customResponseStream.Length;
                owinResponse.StatusCode = 200;
                owinResponse.Body = owinResponseStream;
            }

        }

Answer 2

当您第一次将响应主体设置为内存流时，光标（当前位置）将移动到它的末尾。 owinResponse.Body = responseBuffer; ，因此，我们存储了{"message":"Authorization has been denied for this request."}，光标指向末尾。

同样，在方法末尾，您编写了新的响应owinResponse.Body = owinResponseStream;，其中包含消息{"IsError":true,"StatusCode":401,"Data":null,"Message":"unauthorized request"}

由于当前位置指向流的末尾，因此它将追加。

尝试删除第一组正文 ~~owinResponse.Body = responseBuffer;~~ ，因为您不需要原始回复消息。

覆盖Owin中间件中的响应正文

2 个答案: