如何实现在网页API HttpMessageHandler？ [英] How to implement HttpMessageHandler in Web API?

问题描述

在一个ASP.NET MVC 4.5 4个Web API项目，我想添加自定义的 HttpMessageHandler 。我已经改变了 WebApiConfig 类（在\\ App_Satrt \\ WebApiConfig.cs），如下：

In an ASP.NET 4.5 MVC 4 Web API project, I want to add a custom HttpMessageHandler. I've changed WebApiConfig class (in \App_Satrt\WebApiConfig.cs), as follows:

public static class WebApiConfig
{
    public static void Register(HttpConfiguration config)
    {
        config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "api/{controller}/{id}",
            defaults: new { id = RouteParameter.Optional },
            constraints: null,
            handler: new MyCustomizedHttpMessageHandler()
        );
    }
}

然后我制定 MyCustomizedHttpMessageHandler ：

public class MyCustomizedHttpMessageHandler : HttpMessageHandler
{
    protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        IPrincipal principal = new GenericPrincipal(
            new GenericIdentity("myuser"), new string[] { "myrole" });
        Thread.CurrentPrincipal = principal;
        HttpContext.Current.User = principal;

        return Task<HttpResponseMessage>.Factory.StartNew(() => request.CreateResponse());
    }
}

不过，请求API（假设 http://mylocalhost.com/api/values​​ ），总回报状态code 200，没有任何数据。我的意思是永远不会获取Values​​Controller.cs的GET（）方法。

However, the request to the API (let's say http://mylocalhost.com/api/values), always returns status code 200, without any data. I mean it never gets to ValuesController.cs's 'GET()' method.

什么我错过了？我如何能实现 HttpMessageHandler 是否正确？

What have I missed? How can I implement HttpMessageHandler properly?

PS：已经阅读这一个： http://stackoverflow.com/a/12030785/538387 ，没有按'T帮我。

PS: Have already read this one: http://stackoverflow.com/a/12030785/538387 , doesn't help me.

推荐答案

在这里，您正在创建一个 HttpMessageHandler 这短路请求，并没有让请求通过流水线的其余部分。相反，你应该创建一个 DelegatingHandler 。

Here you are creating a HttpMessageHandler which short circuits the request and doesn't let the request pass through the rest of the pipeline. Instead, you should create a DelegatingHandler.

还有一些在网页API2种消息处理管道。一个是普通的管道中，为所有路由所有请求通过等，其中一个可能有特定于某些航线的消息处理程序只。

Also there are 2 kinds of message handler pipelines in Web API. One is a regular pipeline in which all requests for all routes pass through and other where one could have message handlers specific to certain routes only.

1. 尝试创建一个 DelegatingHandler 并将其添加到消息处理你的 HttpConfiguration 列表：

1. Try to create a DelegatingHandler and add it to your HttpConfiguration's list of message handlers:

config.MessageHandlers.Add(new HandlerA())

如果您要添加的路由特定的消息处理程序，那么你可以做到以下几点：

If you want to add a route specific message handler, then you could do the following:

config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "api/{controller}/{id}",
            defaults: new { id = RouteParameter.Optional },
            constraints: null,
            handler: 
                   HttpClientFactory.CreatePipeline(
                          new HttpControllerDispatcher(config), 
                          new DelegatingHandler[]{new HandlerA()})
            );

此网页API海报显示管道流

这篇关于如何实现在网页API HttpMessageHandler？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！