WebApi2官网学习记录---批量处理HTTP Message

原文：Batching Handler for ASP.NET Web API

1. 自定义实现HttpMessageHandler

      public class BatchHandler : HttpMessageHandler
        {
            HttpMessageInvoker _server;
   
            public BatchHandler(HttpConfiguration config)
            {
                _server = new HttpMessageInvoker(new HttpServer(config));
            }
   
            protected override async Task<HttpResponseMessage> SendAsync(
                HttpRequestMessage request,
                CancellationToken cancellationToken)
            {
                // Return 400 for the wrong MIME type
                if ("multipart/batch" !=
                    request.Content.Headers.ContentType.MediaType)
                {
                    return request.CreateResponse(HttpStatusCode.BadRequest);
                }
   
                // Start a multipart response
                var outerContent = new MultipartContent("batch");
                var outerResp = request.CreateResponse();
                outerResp.Content = outerContent;
   
                // Read the multipart request
                var multipart = await request.Content.ReadAsMultipartAsync();
   
                foreach (var httpContent in multipart.Contents)
                {
                    HttpResponseMessage innerResp = null;
   
                    try
                    {
                        // Decode the request object
                        var innerReq = await
                            httpContent.ReadAsHttpRequestMessageAsync();
   
                        // Send the request through the pipeline
                        innerResp = await _server.SendAsync(
                            innerReq,
                            cancellationToken
                        );
                    }
                    catch (Exception)
                    {
                        // If exceptions are thrown, send back generic 400
                        innerResp = new HttpResponseMessage(
                            HttpStatusCode.BadRequest
                        );
                    }
   
                    // Wrap the response in a message content and put it
                    // into the multipart response
                    outerContent.Add(new HttpMessageContent(innerResp));
                }
   
                return outerResp;
            }
        }
   

2. 配置Web Api config

     var batchHandler = new BatchHandler(config);
   
    config.Routes.MapHttpRoute("batch", "api/batch",
                               null, null, batchHandler);
   
    config.Routes.MapHttpRoute("default", "api/{controller}/{id}",
                               new { id = RouteParameter.Optional });
   

3. 模拟请求

    var client = new HttpClient();
    var batchRequest = new HttpRequestMessage(
        HttpMethod.Post,
        "http://localhost/api/batch"
    );
   
    var batchContent = new MultipartContent("batch");
    batchRequest.Content = batchContent;
   
    batchContent.Add(
        new HttpMessageContent(
            new HttpRequestMessage(
                HttpMethod.Get,
                "http://localhost/api/values"
            )
        )
    );
   
    batchContent.Add(
        new HttpMessageContent(
            new HttpRequestMessage(
                HttpMethod.Get,
                "http://localhost/foo/bar"
            )
        )
    );
   
    batchContent.Add(
        new HttpMessageContent(
            new HttpRequestMessage(
                HttpMethod.Get,
                "http://localhost/api/values/1"
            )
        )
    );
   
    using (Stream stdout = Console.OpenStandardOutput())
    {
        Console.WriteLine("<<< REQUEST >>>");
        Console.WriteLine();
        Console.WriteLine(batchRequest);
        Console.WriteLine();
        batchContent.CopyToAsync(stdout).Wait();
        Console.WriteLine();
   
        var batchResponse = client.SendAsync(batchRequest).Result;
   
        Console.WriteLine("<<< RESPONSE >>>");
        Console.WriteLine();
        Console.WriteLine(batchResponse);
        Console.WriteLine();
        batchResponse.Content.CopyToAsync(stdout).Wait();
        Console.WriteLine();
        Console.WriteLine();
    }
   

结果如下：

<<< REQUEST >>>

Method: POST,

RequestUri: 'http://localhost/api/batch',

Version: 1.1,

Content: System.Net.Http.MultipartContent,

Headers:

{

Content-Type: multipart/batch; boundary="3bc5bd67-3517-4cd0-bcdd-9d23f3850402"

}

--3bc5bd67-3517-4cd0-bcdd-9d23f3850402

Content-Type: application/http; msgtype=request

GET /api/values HTTP/1.1

Host: localhost

--3bc5bd67-3517-4cd0-bcdd-9d23f3850402

Content-Type: application/http; msgtype=request

GET /foo/bar HTTP/1.1

Host: localhost

--3bc5bd67-3517-4cd0-bcdd-9d23f3850402--

<<< RESPONSE >>>

StatusCode: 200,

ReasonPhrase: 'OK',

Version: 1.1,

Content: System.Net.Http.StreamContent,

Headers:

{

Pragma: no-cache

Cache-Control: no-cache

Date: Thu, 21 Jun 2012 00:21:40 GMT

Server: Microsoft-IIS/8.0

X-AspNet-Version: 4.0.30319

X-Powered-By: ASP.NET

Content-Length: 658

Content-Type: multipart/batch

Expires: -1

}

--3d1ba137-ea6a-40d9-8e34-1b8812394baa

Content-Type: application/http; msgtype=response

HTTP/1.1 200 OK

Content-Type: application/json; charset=utf-8

["Hello","world!"]

--3d1ba137-ea6a-40d9-8e34-1b8812394baa

Content-Type: application/http; msgtype=response

HTTP/1.1 404 Not Found

Content-Type: application/json; charset=utf-8

{"Message":"No HTTP resource was found that matches the request URI 'http://localhost/foo/bar'."}

--3d1ba137-ea6a-40d9-8e34-1b8812394baa

Content-Type: application/http; msgtype=response