您可以添加一个处理程序来处理这种类型的请求。
创建一个派生自“DelegatingHandler”的类：
public class PreflightRequestsHandler : DelegatingHandler
{
protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
if (request.Headers.Contains("Origin") && request.Method.Method.Equals("OPTIONS"))
{
var response = new HttpResponseMessage { StatusCode = HttpStatusCode.OK };
// Define and add values to variables: origins, headers, methods (can be global)
response.Headers.Add("Access-Control-Allow-Origin", origins);
response.Headers.Add("Access-Control-Allow-Headers", headers);
response.Headers.Add("Access-Control-Allow-Methods", methods);
var tsc = new TaskCompletionSource<HttpResponseMessage>();
tsc.SetResult(response);
return tsc.Task;
}
return base.SendAsync(request, cancellationToken);
}
}
稍后在 WebApiconfig.cs 的 Register 方法中添加以下内容：
public static void Register(HttpConfiguration config)
{
// Define and add values to variables: origins, headers, methods (can be global)
// Enable global CORS
config.EnableCors(new EnableCorsAttribute(origins, headers, methods));
// Add handler to deal with preflight requests, this is the important part
config.MessageHandlers.Add(new PreflightRequestsHandler()); // Defined above
.
.
.
}