c# - 在消息处理程序中添加属性值

Question

我想在 asp.net webapi 的消息处理程序中添加属性值。场景是我实现了 webapi，其中 authenticationToken 是不同请求的一部分，但客户端要求我在请求 header 中接受 token 。但一些应用程序已经在使用此 api 在请求正文中发送 token 。所以我不想改变实现。我想读取请求 header ，如果它包含 header ，则将该值分配给请求的属性。可能吗？

Answer 1

是的，可以在消息处理程序中修改您的请求 uri 和 formdata。这是一个例子，你可以试试这个。我添加了一个 class APIKeyHandler 来处理这个问题，并在我的 WebApiConfig 中添加了处理程序。我已经在我的 Git 中上传了一个解决方案，您可以从 Example WebAPI with Modify Request Body in MessageHandler 查看它

WebApiConfig代码:

public static class WebApiConfig
{
    public static void Register(HttpConfiguration config)
    {
        System.Web.Routing.RouteTable.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "api/{controller}/{action}/{id}",
            defaults: new { id = RouteParameter.Optional }
        );

        //add the handler class in WebApiConfig
        config.MessageHandlers.Add(new APIKeyHandler());
    }
}

APIKeyHandler代码:

public class APIKeyHandler : DelegatingHandler
{
    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        var formData = await request.Content.ReadAsFormDataAsync();
        if (request.Method.Method.Equals("POST"))
        {
            request.Content = new FormUrlEncodedContent(ModifyYourFormData(formData, request));
        }
        request.RequestUri = new Uri(ModifyYourURI(request.RequestUri.ToString(), request), UriKind.Absolute);

        return await base.SendAsync(request, cancellationToken);
    }

    public IEnumerable<KeyValuePair<string, string>> ModifyYourFormData(NameValueCollection source, HttpRequestMessage request)
    {
        //Add your logic here

        string Authorized = "";
        try
        {
            Authorized = request.Headers.GetValues("AuthorizedKey").FirstOrDefault();
        }
        catch (Exception ex)
        {

        }

        List<KeyValuePair<string, string>> formData;
        formData = source.AllKeys.SelectMany(
            source.GetValues,
            (k, v) => new KeyValuePair<string, string>(k, v)).ToList();

        if (!string.IsNullOrEmpty(Authorized))
        {
            formData.Insert(0, new KeyValuePair<string, string>("AuthorizedKey", Authorized)); 
        }

        return formData;
    }

    public string ModifyYourURI(string uri, HttpRequestMessage request)
    {
        //Add your logic here

        string Authorized = "";
        try
        {
            Authorized = request.Headers.GetValues("AuthorizedKey").FirstOrDefault();
        }
        catch (Exception ex)
        {

        }

        if (!string.IsNullOrEmpty(Authorized))
        {
            return uri + "?AuthorizedKey="+ Authorized;
        }
        else
        {
            return uri;
        }
    }
}

ExampleAPIController代码:

public class ExampleAPIController : ApiController
{
    public async Task<string> Post()
    {
        string returnValue = "OK";

        var formKeyValueData = await Request.Content.ReadAsFormDataAsync();

        string AuthorizedKey = formKeyValueData["AuthorizedKey"];

        return returnValue;
    }

    public string Get(string AuthorizedKey)
    {
        string returnValue = "OK";
        return returnValue;
    }
}

POST 请求调用示例:

GET 请求调用示例: