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MyCode.Project.WebApi/OAuth/CrosHandler.cs

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+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net.Http;
+using System.Threading;
+using System.Threading.Tasks;
+using System.Web;
+
+namespace MyCode.Project.WebApi.OAuth
+{
+	/// <summary>
+	/// CORS跨域处理器
+	/// </summary>
+	public class CrosHandler : 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 AccessControlAllowOrign = "Access-Control-Allow-Origin";
+		private const string AccessControlAllowMethods = "Access-Control-Allow-Methods";
+		private const string AccessControlAllowHeaders = "Access-Control-Allow-Headers";
+		private const string AccessControlAllowCredentials = "Access-Control-Allow-Credentials";
+		// <add name = "Access-Control-Allow-Headers" value="Content-Type" />
+		// <add name = "Access-Control-Allow-Methods" value="GET, POST, PUT, DELETE, OPTIONS" />
+		protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
+		{
+			bool isCrosRequest = request.Headers.Contains(Origin);
+			bool isPrefilightRequest = request.Method == HttpMethod.Options;
+			if (isCrosRequest)
+			{
+				Task<HttpResponseMessage> taskResult = null;
+				if (isPrefilightRequest)
+				{
+					taskResult = Task.Factory.StartNew<HttpResponseMessage>(() =>
+					{
+						HttpResponseMessage response = new HttpResponseMessage(System.Net.HttpStatusCode.OK);
+						response.Headers.Add(AccessControlAllowOrign,
+							request.Headers.GetValues(Origin).FirstOrDefault());
+						string method = request.Headers.GetValues(AccessControlRequestMethod).FirstOrDefault();
+						//if (method != null)
+						//{
+						//    response.Headers.Add(AccessControlAllowMethods, method);
+						//}
+						string headers = string.Join(", ", request.Headers.GetValues(AccessControlRequestHeaders));
+						if (!string.IsNullOrWhiteSpace(headers))
+						{
+							response.Headers.Add(AccessControlAllowHeaders, headers);
+						}
+						response.Headers.Add(AccessControlAllowCredentials, "true");
+						return response;
+					}, cancellationToken);
+				}
+				else
+				{
+					taskResult = base.SendAsync(request, cancellationToken).ContinueWith<HttpResponseMessage>(t =>
+					{
+						var response = t.Result;
+						response.Headers.Add(AccessControlAllowOrign,
+							request.Headers.GetValues(Origin).FirstOrDefault());
+						response.Headers.Add(AccessControlAllowCredentials, "true");
+						return response;
+					});
+				}
+				return taskResult;
+			}
+			return base.SendAsync(request, cancellationToken);
+		}
+	}
+}