C# 中的 HttpClient 多部分表单发布

Question

我正在尝试使用 C# 中的 HttpClient 进行多部分表单发布，但发现以下代码不起作用。

重要：

var jsonToSend = JsonConvert.SerializeObject(json, Formatting.None, new IsoDateTimeConverter());
var multipart = new MultipartFormDataContent();
var body = new StringContent(jsonToSend, Encoding.UTF8, "application/json");

multipart.Add(body);
multipart.Add(new ByteArrayContent(File.ReadAllBytes("test.txt")), "test", "test.txt");

var httpClient = new HttpClient();
var response = httpClient.PostAsync(new Uri("http://localhost:55530"), multipart).Result;

完整程序：

namespace CourierMvc.Worker
{
    class Program
    {
        static void Main(string[] args)
        {
            while (true)
            {
                Console.WriteLine("Hit any key to make request.");
                Console.ReadKey();

                try
                {
                    var request = new RestRequest(Method.POST)
                    {
                        Resource = "http://localhost:55530"
                    };

                    var json = new CourierMessage
                    {
                        Id = Guid.NewGuid().ToString(),
                        Key = "awesome",
                        From = "khalid@home.com",
                        To = new[] { "me@test.com", "you@test.com" },
                        Subject = "test",
                        Body = "body",
                        Processed = DateTimeOffset.UtcNow,
                        Received = DateTime.Now,
                        Created = DateTime.Now,
                        Sent = DateTime.Now,
                        Links = new[] { new Anchor { Link = "http://google.com" }, new Anchor { Link = "http://yahoo.com" } }
                    };

                    var jsonToSend = JsonConvert.SerializeObject(json, Formatting.None, new IsoDateTimeConverter());
                    var multipart = new MultipartFormDataContent();
                    var body = new StringContent(jsonToSend, Encoding.UTF8, "application/json");

                    multipart.Add(body);
                    multipart.Add(new ByteArrayContent(File.ReadAllBytes("test.txt")), "test", "test.txt");

                    var httpClient = new HttpClient();
                    var response = httpClient.PostAsync(new Uri("http://localhost:55530"), multipart).Result;

                }
                catch (Exception e)
                {
                    Console.WriteLine(e);
                }
            }
        }
    }
}

我真的不知道为什么它不起作用。我将文件发布到端点，但正文（json）永远不会到达那里。我做错了吗？

服务器端代码请求：

namespace CourierMvc.Controllers
{
    public class HomeController : Controller
    {
        //
        // GET: /Home/

        public ActionResult Index()
        {
            return Content("Home#Index");
        }


        [ValidateInput(false)]
        public ActionResult Create(CourierMessage input)
        {
            var files = Request.Files;

            return Content("OK");
        }

    }
}

路线配置：

public static void RegisterRoutes(RouteCollection routes)
{
    routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

    routes.MapRoute(
        name: "Default",
        url: "{controller}/{action}/{id}",
        defaults: new { controller = "Home", action = "Create", id = UrlParameter.Optional }
    );

}

Answer 1

public class CourierMessage
{
    public string Id { get; set; }
    public string Key { get; set; }
    public string From { get; set; }
    public string Subject { get; set; }
    public string Body { get; set; }
    public DateTimeOffset Processed { get; set; }
    public DateTime Received { get; set; }
    public DateTime Created { get; set; }
    public DateTime Sent { get; set; }
    public HttpPostedFileBase File { get; set; }
}  




while (true)
{
    Console.WriteLine("Hit any key to make request.");
    Console.ReadKey();

    using (var client = new HttpClient())
    {
        using (var multipartFormDataContent = new MultipartFormDataContent())
        {
            var values = new[]
            {
                new KeyValuePair<string, string>("Id", Guid.NewGuid().ToString()),
                new KeyValuePair<string, string>("Key", "awesome"),
                new KeyValuePair<string, string>("From", "khalid@home.com")
                 //other values
            };

            foreach (var keyValuePair in values)
            {
                multipartFormDataContent.Add(new StringContent(keyValuePair.Value), 
                    String.Format("\"{0}\"", keyValuePair.Key));
            }

            multipartFormDataContent.Add(new ByteArrayContent(File.ReadAllBytes("test.txt")), 
                '"' + "File" + '"', 
                '"' + "test.txt" + '"');

            var requestUri = "http://localhost:5949";
            var result = client.PostAsync(requestUri, multipartFormDataContent).Result;
        }
    }
}  

Answer 2

这是一个如何通过 HTTPClient 使用 MultipartFormDataContent 发布字符串和文件流的示例。需要为每个 HTTPContent 指定 Content-Disposition 和 Content-Type：

这是我的例子。希望对您有所帮助：

private static void Upload()
{
    using (var client = new HttpClient())
    {
        client.DefaultRequestHeaders.Add("User-Agent", "CBS Brightcove API Service");

        using (var content = new MultipartFormDataContent())
        {
            var path = @"C:\B2BAssetRoot\files\596086\596086.1.mp4";

            string assetName = Path.GetFileName(path);

            var request = new HTTPBrightCoveRequest()
            {
                Method = "create_video",
                Parameters = new Params()
                {
                    CreateMultipleRenditions = "true",
                    EncodeTo = EncodeTo.Mp4.ToString().ToUpper(),
                    Token = "x8sLalfXacgn-4CzhTBm7uaCxVAPjvKqTf1oXpwLVYYoCkejZUsYtg..",
                    Video = new Video()
                    {
                        Name = assetName,
                        ReferenceId = Guid.NewGuid().ToString(),
                        ShortDescription = assetName
                    }
                }
            };

            //Content-Disposition: form-data; name="json"
            var stringContent = new StringContent(JsonConvert.SerializeObject(request));
            stringContent.Headers.Add("Content-Disposition", "form-data; name=\"json\"");
            content.Add(stringContent, "json");

            FileStream fs = File.OpenRead(path);

            var streamContent = new StreamContent(fs);
            streamContent.Headers.Add("Content-Type", "application/octet-stream");
            streamContent.Headers.Add("Content-Disposition", "form-data; name=\"file\"; filename=\"" + Path.GetFileName(path) + "\"");
            content.Add(streamContent, "file", Path.GetFileName(path));

            //content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment");

            Task<HttpResponseMessage> message = client.PostAsync("http://api.brightcove.com/services/post", content);

            var input = message.Result.Content.ReadAsStringAsync();
            Console.WriteLine(input.Result);
            Console.Read();
        }
    }
}

Answer 3

所以我看到的问题是MultipartFormDataContent 请求消息将始终将请求的内容类型设置为“multipart/form-data”。结束 json 编码并将其放入请求中，仅“看起来”像模型绑定器作为字符串。

您的选择是：

• 让您的 mvc 操作方法接收一个字符串并反序列化到您的对象中
• 将模型的每个属性作为表单部分发布
• 创建一个自定义模型绑定器来处理您的请求。
• 把操作分成两个post，第一个发送json元数据，另一个发送文件。来自服务器的响应应该发送一些 id 或 key 来关联这两个请求。

通读the RFC document 和the MSDN documentation，如果您将MultipartFormDataContent 替换为MultipartContent，您或许可以做到这一点。但我还没有测试过。

Answer 4

string path = @"C:\New folder\Test.pdf";  // **ANY FILE**
                            
var formContent = new MultipartFormDataContent
{
     { new ByteArrayContent(File.ReadAllBytes(path)), "file", Path.GetFileName(path) }
};

var client = new HttpClient();
var response = client.PostAsync(_configuration["Url"], formContent).Result;