Download the completed project.
下载完整的项目。

<form name="form1" method="post" enctype="multipart/form-data" action="api/upload"><div><label for="caption">Image Caption</label><input name="caption" type="text" /></div><div><label for="image1">Image File</label><input name="image1" type="file" /></div><div><input type="submit" value="Submit" /></div>
</form>

图5-8. 文件上传表单

POST http://localhost:50460/api/values/1 HTTP/1.1
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:12.0) Gecko/20100101 Firefox/12.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip, deflate
Content-Type: multipart/form-data; boundary=---------------------------41184676334
Content-Length: 29278
-----------------------------41184676334
Content-Disposition: form-data; name="caption"
Summer vacation
-----------------------------41184676334
Content-Disposition: form-data; name="image1"; filename="GrandCanyon.jpg"
Content-Type: image/jpeg
(Binary data not shown)（二进制数据，未列出）
-----------------------------41184676334--

The part boundary includes a random component ("41184676334") to ensure that the boundary string does not accidentally appear inside a message part.
部件边界包含了一个随机组件（“41184676334”），以确保边界字符串不会偶然出现在消息部件之中。

using System.Diagnostics;
using System.Net;
using System.Net.Http;
using System.Threading.Tasks;
using System.Web;
using System.Web.Http;
public class UploadController : ApiController
{public async Task<HttpResponseMessage> PostFormData(){// Check if the request contains multipart/form-data.// 检查该请求是否含有multipart/form-dataif (!Request.Content.IsMimeMultipartContent()){throw new HttpResponseException(HttpStatusCode.UnsupportedMediaType);}string root = HttpContext.Current.Server.MapPath("~/App_Data");var provider = new MultipartFormDataStreamProvider(root); try{// Read the form data.// 读取表单数据await Request.Content.ReadAsMultipartAsync(provider); // This illustrates how to get the file names.// 以下描述如何获取文件名foreach (MultipartFileData file in provider.FileData){Trace.WriteLine(file.Headers.ContentDisposition.FileName);Trace.WriteLine("Server file path: " + file.LocalFileName);}return Request.CreateResponse(HttpStatusCode.OK);}catch (System.Exception e){return Request.CreateErrorResponse(HttpStatusCode.InternalServerError, e);}}
}

public Task<HttpResponseMessage> PostFormData()
{// Check if the request contains multipart/form-data.// 检查该请求是否含有multipart/form-dataif (!Request.Content.IsMimeMultipartContent()){throw new HttpResponseException(HttpStatusCode.UnsupportedMediaType);}string root = HttpContext.Current.Server.MapPath("~/App_Data");var provider = new MultipartFormDataStreamProvider(root); // Read the form data and return an async task.// 读取表单数据，并返回一个async任务var task = Request.Content.ReadAsMultipartAsync(provider).ContinueWith<HttpResponseMessage>(t =>{if (t.IsFaulted || t.IsCanceled){Request.CreateErrorResponse(HttpStatusCode.InternalServerError, t.Exception);}// This illustrates how to get the file names.// 以下描述了如何获取文件名foreach (MultipartFileData file in provider.FileData){Trace.WriteLine(file.Headers.ContentDisposition.FileName);Trace.WriteLine("Server file path: " + file.LocalFileName);}return Request.CreateResponse(HttpStatusCode.OK);});return task;
}

    <div><label for="caption">Image Caption</label><input name="caption" type="text" /></div>

public async Task<HttpResponseMessage> PostFormData()
{if (!Request.Content.IsMimeMultipartContent()){throw new HttpResponseException(HttpStatusCode.UnsupportedMediaType);}string root = HttpContext.Current.Server.MapPath("~/App_Data");var provider = new MultipartFormDataStreamProvider(root); try{await Request.Content.ReadAsMultipartAsync(provider); // Show all the key-value pairs.// 显示所有“键-值”对foreach (var key in provider.FormData.AllKeys){foreach (var val in provider.FormData.GetValues(key)){Trace.WriteLine(string.Format("{0}: {1}", key, val));}}return Request.CreateResponse(HttpStatusCode.OK);}catch (System.Exception e){return Request.CreateErrorResponse(HttpStatusCode.InternalServerError, e);}
}

<form name="trip_search" method="post" enctype="multipart/form-data" action="api/upload"><div><input type="radio" name="trip" value="round-trip"/>Round-Trip</div><div><input type="radio" name="trip" value="one-way"/>One-Way</div> <div><input type="checkbox" name="options" value="nonstop" />Only show non-stop flights</div><div><input type="checkbox" name="options" value="airports" />Compare nearby airports</div><div><input type="checkbox" name="options" value="dates" />My travel dates are flexible</div> <div><label for="seat">Seating Preference</label><select name="seat"><option value="aisle">Aisle</option><option value="window">Window</option><option value="center">Center</option><option value="none">No Preference</option></select></div>
</form>

图5-9. 有重复键的表单

-----------------------------7dc1d13623304d6
Content-Disposition: form-data; name="trip"
round-trip
-----------------------------7dc1d13623304d6
Content-Disposition: form-data; name="options"
nonstop
-----------------------------7dc1d13623304d6
Content-Disposition: form-data; name="options"
dates
-----------------------------7dc1d13623304d6
Content-Disposition: form-data; name="seat"
window
-----------------------------7dc1d13623304d6--