概述
问题
原因
解决方法
方法一
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";
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);
}
}
protected void Application_Start()
{
IOCConfig.RegisterAll();
AreaRegistration.RegisterAllAreas();
WebApiConfig.Register(GlobalConfiguration.Configuration);
FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
RouteConfig.RegisterRoutes(RouteTable.Routes);
BundleConfig.RegisterBundles(BundleTable.Bundles);
GlobalConfiguration.Configuration.MessageHandlers.Add(new CrosHandler());
}
方法二
<system.webServer>
<httpProtocol>
<customHeaders>
<add name="Access-Control-Allow-Origin" value="*" />
<add name="Access-Control-Allow-Headers" value="Content-Type" />
<add name="Access-Control-Allow-Methods" value="GET, POST,OPTIONS" />
</customHeaders>
</httpProtocol>
<system.webServer>
参考文献
https://code.msdn.microsoft.com/windowsdesktop/Implementing-CORS-support-a677ab5d#content