c#实现跨域文件传输具体代码

下面是一份C#实现跨域文件传输的示例代码：

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Web;
using System.Web.Http;
using System.Web.Http.Cors;

namespace WebApplication1.Controllers
{
    [EnableCors(origins: "*", headers: "*", methods: "*")]
    public class FileController : ApiController
    {
        [HttpPost]
        public HttpResponseMessage UploadFile()
        {
            HttpResponseMessage response = new HttpResponseMessage();

            if (!Request.Content.IsMimeMultipartContent())
            {
                response.StatusCode = HttpStatusCode.BadRequest;
                response.ReasonPhrase = "不支持的媒体类型";
                return response;
            }

            var provider = new MultipartMemoryStreamProvider();
            Request.Content.ReadAsMultipartAsync(provider).Wait();

            foreach (var file in provider.Contents)
            {
                var filename = file.Headers.ContentDisposition.FileName.Trim('\"');
                var buffer = file.ReadAsByteArrayAsync().Result;

                // 处理上传的文件
                var path = HttpContext.Current.Server.MapPath("~/Uploads/" + filename);
                File.WriteAllBytes(path, buffer);
            }

            response.StatusCode = HttpStatusCode.OK;
            response.Content = new StringContent("上传成功");
            return response;
        }
    }
}

这是一个ASP.NET Web API控制器，使用了EnableCors特性启用了跨域支持，不限制请求来源、请求头和请求方法。在上传文件时，先判断请求是否为multipart/form-data类型，然后使用MultipartMemoryStreamProvider类将上传的文件读取到内存中，最后将文件保存到指定目录中。上传成功后，返回一个状态码为200的响应和一个上传成功的消息。