如何在Asp Net Web Api中默认返回404

public class NotFoundHandler : DelegatingHandler
{
    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        var response = await base.SendAsync(request, cancellationToken);

        if (response.StatusCode == HttpStatusCode.NotFound)
        {
            // 构造一个新的HTTP响应，状态码为404
            var notFoundResponse = request.CreateResponse(HttpStatusCode.NotFound, "Resource not found");
            return notFoundResponse;
        }

        return response;
    }
}

public static class WebApiConfig
{
    public static void Register(HttpConfiguration config)
    {
        // 注册NotFoundHandler类
        config.MessageHandlers.Add(new NotFoundHandler());

        // 其他配置...
    }
}