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