asp.net webapi中的自定义批处理程序

Question

我想在我的webapi中编写自定义批处理程序。

对此的要求：我无法识别传入请求是批处理或独立的一部分的天气。

通过编写自定义批处理程序，我将能够在每个请求的标题中添加值，我可以稍后使用它来标识。

Answer 1

首先，我们需要编写自定义批处理hahttps：//stackoverflow.blog/2011/07/01/its-ok-to-ask-and-answer-your-own-questions/ndler 为此，我们需要覆盖HttpMessageHandler。下面是在上面的代码代码

public class BatchHandler : HttpMessageHandler 
{ 
    HttpMessageInvoker _server; 

    public BatchHandler(HttpConfiguration config) 
    { 
     // BatchServer is a class which overrides 
     _server = new HttpMessageInvoker(new BatchServer(config)); 
    } 

    protected override async Task<HttpResponseMessage> SendAsync(
     HttpRequestMessage request, 
     CancellationToken cancellationToken) 
    { 
     // Return 400 for the wrong MIME type 
     // As batch request will always be of MIME type 
     if ("multipart/mixed" != 
      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(); 

       innerReq.Headers.Add("IsBatch", "true"); 

       // Send the request through the pipeline 
       innerResp = await _server.SendAsync(
        innerReq, 
        cancellationToken 
       ); 

      } 
      catch (Exception ex) 
      { 
       // 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; 
    } 
} 

他们是这条线

// BatchServer is a class which overrides HttpServer 
_server = new HttpMessageInvoker(new BatchServer(config)); 

，如果我们不这样做，我们会得到一个错误

的“DelegatingHandler名单是无效的，因为property 'xxhandler'的'InnerHandler'不为null。\ r \ n参数 名称：处理程序

下面是BatchServer类覆盖的HttpServer

public class BatchServer : HttpServer 
{ 
    private readonly HttpConfiguration _config; 

    public BatchServer(HttpConfiguration configuration) 
     : base(configuration) 
    { 
     _config = configuration; 
    } 

    protected override void Initialize() 
    { 
     var firstInPipeline = _config.MessageHandlers.FirstOrDefault(); 
     if (firstInPipeline != null && firstInPipeline.InnerHandler != null) 
     { 
      InnerHandler = firstInPipeline; 
     } 
     else 
     { 
      base.Initialize(); 
     } 
    } 
} 

现在我们想打BatchHandler 批量要求为此，我们需要配置路由BatchHandler 添加下面的代码到你的AppStart的

var batchHandler = new BatchHandler(config); 
config.Routes.MapHttpRoute("batch", "api/batch", null, null, batchHandler);