消息攔截器是一個類，接收 HTTP request并返回 HTTP response,Message handler 繼承自抽象類 HttpMessageHandler
可以自定義 MessageHandler,消息攔截器的作用如:
- 讀取或更改請求頭 request headers
- 添加 response headers
- 在到達 controller 之前，進行參數(shù)驗證
自定義 Message Handlers
自定義 MessageHandler 需要繼承 System.Net.Http.DelegatingHander 并且重載SendAsync方法
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Task<HttpResponseMessage> SendAsync( HttpRequestMessage request, CancellationToken cancellationToken); |
這個方法的一般的處理流程是
- 處理請求信息
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調(diào)用
base.SendAsync方法，吧請求發(fā)送給內(nèi)部處理 -
內(nèi)部處理完成之后，返回
response message(這個過程是異步的) -
處理
response之后，返回給調(diào)用者
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public class MessageHandler1 : DelegatingHandler{ protected async override Task<HttpResponseMessage> SendAsync( HttpRequestMessage request, CancellationToken cancellationToken) { Debug.WriteLine("Process request"); // Call the inner handler. var response = await base.SendAsync(request, cancellationToken); Debug.WriteLine("Process response"); return response; }} |
消息攔截器生效
在 WebApiConfig中注冊相關(guān)
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public static class WebApiConfig{ public static void Register(HttpConfiguration config) { config.MessageHandlers.Add(new MessageHandler1()); config.MessageHandlers.Add(new MessageHandler2()); // Other code not shown... }} |
https 請求攔截器
要求所有的請求都必須是https的請求，可以自定義一個https的攔截器，如果是https請求，就繼續(xù)處理，否則就返回相關(guān)的提示信息
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public class RequireHttpsHandler : DelegatingHandler{ public RequireHttpsHandler(int httpsPort) { _httpsPort = httpsPort; } public RequireHttpsHandler() : this(443) { } protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { //判斷是否是 https 請求 if (request.RequestUri.Scheme == Uri.UriSchemeHttps) return base.SendAsync(request, cancellationToken); var response = CreateResponse(request); var tcs = new TaskCompletionSource<HttpResponseMessage>(); tcs.SetResult(response); return tcs.Task; } private HttpResponseMessage CreateResponse(HttpRequestMessage request) { HttpResponseMessage response; var uri = new UriBuilder(request.RequestUri); uri.Scheme = Uri.UriSchemeHttps; uri.Port = _httpsPort; var body = string.Format("HTTPS is required<br/>The resource can be found at <a href="{0}">{0}</a>.", uri.Uri.AbsoluteUri); if (request.Method.Equals(HttpMethod.Get) || request.Method.Equals(HttpMethod.Head)) { response = request.CreateResponse(HttpStatusCode.Found); response.Headers.Location = uri.Uri; if (request.Method.Equals(HttpMethod.Get)) response.Content = new StringContent(body, Encoding.UTF8, "text/html"); } else { response = request.CreateResponse(HttpStatusCode.NotFound); response.Content = new StringContent(body, Encoding.UTF8, "text/html"); } return response; }} |
Enable CORS 攔截器
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public class SimpleCorsHandler : DelegatingHandler{ private const string origin = "Origin"; private const string accessControlRequestMethod = "Access-Control-Request-Method"; private const string accessControlRequestHeaders = "Access-Control-Request-Headers"; private const string accessControlAllowOrigin = "Access-Control-Allow-Origin"; private const string accessControlAllowMethods = "Access-Control-Allow-Methods"; private const string accessControlAllowHeaders = "Access-Control-Allow-Headers"; protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) { var isCorsRequest = request.Headers.Contains(origin); var isPreflightRequest = request.Method == HttpMethod.Options; if (isCorsRequest) { if (isPreflightRequest) { return Task.Factory.StartNew(() => { var response = new HttpResponseMessage(HttpStatusCode.OK); response.Headers.Add(accessControlAllowOrigin, request.Headers.GetValues(origin).First()); var currentAccessControlRequestMethod = request.Headers.GetValues(accessControlRequestMethod). FirstOrDefault(); if (currentAccessControlRequestMethod != null) { response.Headers.Add(accessControlAllowMethods, currentAccessControlRequestMethod); } var requestedHeaders = string.Join(", ", request.Headers.GetValues(accessControlRequestHeaders)); if (!string.IsNullOrEmpty(requestedHeaders)) { response.Headers.Add(accessControlAllowHeaders, requestedHeaders); } return response; }, cancellationToken); } else { return base.SendAsync(request, cancellationToken).ContinueWith(t => { var resp = t.Result; resp.Headers.Add( accessControlAllowOrigin, request.Headers.GetValues(origin).First()); return resp; }); } } else { return base.SendAsync(request, cancellationToken); } }} |
以上就是本文的全部內(nèi)容，希望對大家的學(xué)習(xí)有所幫助，也希望大家多多支持服務(wù)器之家。
原文鏈接：https://www.jianshu.com/p/a38487f9b692
