原文：

客户端在请求Web Api时可以有以下两种方式提供API key

• 基于Querystring提供Api key

• 基于Request header体统API key

client.BaseAddress = new Uri(url);client.DefaultRequestHeaders.Accept.Clear();client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));client.DefaultRequestHeaders.Add("X-ApiKey","00000");

编写ApiKeyHandler

public class ApiKeyHandler : DelegatingHandler    {        public string Key { get; set; }        public ApiKeyHandler(string key,HttpConfiguration httpConfiguration)        {            this.Key = key;            InnerHandler = new HttpControllerDispatcher(httpConfiguration);         }        protected override Task
       
         SendAsync(            HttpRequestMessage request, CancellationToken cancellationToken)        {            if (!ValidateKey(request))            {                var response = new HttpResponseMessage(HttpStatusCode.Forbidden);                var tsc = new TaskCompletionSource
        
         ();                tsc.SetResult(response);                return tsc.Task;            }            return base.SendAsync(request, cancellationToken);        }        private bool ValidateKey(HttpRequestMessage message)        {            IEnumerable
         
           apiKeyHeaderValues = null;            if (message.Headers.TryGetValues("X-ApiKey", out apiKeyHeaderValues))            {                var apiKeyHeaderValue = apiKeyHeaderValues.First();                  return (apiKeyHeaderValue == this.Key)                // ... your authentication logic here ...                /*               var username = (apiKeyHeaderValue == "00000" ? "Maarten" : "OtherUser");               var usernameClaim = new Claim(ClaimTypes.Name, username);                var identity = new ClaimsIdentity(new[] { usernameClaim }, "ApiKey");                var principal = new ClaimsPrincipal(identity);                Thread.CurrentPrincipal = principal;             */            }            /*            var query = message.RequestUri.ParseQueryString();            string key = query["key"];            return (key == this.Key);            */        }
         
        
       

配置到特定的路由上去

config.Routes.MapHttpRoute(                name: "DefaultApi",                routeTemplate: "api/{controller}/{id}",                defaults: new { id = RouteParameter.Optional },                constraints: null,                handler: new ApiKeyHandler("12345", GlobalConfiguration.Configuration)                            );