C#的HttpWebRequest发送form-data数据

以下是使用C#中的HttpWebRequest发送post请求的示例代码，请求头为form-data，可以上传文件。你可以将它封装成一个通用的方法。

 1 public static string HttpPost(string url, Dictionary<string, string> parameters, Dictionary<string, string> files)
 2 {
       string strBoundary = "qwwg-" + DateTime.Now.Ticks.ToString("x");//程序生成
 3     HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
 4     request.Method = "POST";
 5     request.ContentType = "multipart/form-data;charset=UTF-8; boundary=" + strBoundary; 6     
 7     // 设置请求参数
 8     StringBuilder sb = new StringBuilder();
 9     foreach (KeyValuePair<string, string> kvp in parameters)
10     {
11         sb.AppendFormat("--"+ strBoundary + "\r\n");12         sb.AppendFormat("Content-Disposition: form-data; name=\"{0}\"\r\n", kvp.Key);
13         sb.AppendFormat("\r\n{0}\r\n", kvp.Value);
14     }
15     
16     // 上传文件
17     foreach (KeyValuePair<string, string> kvp in files)
18     {
19         sb.AppendFormat("--"+ strBoundary + "\r\n");20         sb.AppendFormat("Content-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"\r\n", kvp.Key, Path.GetFileName(kvp.Value));
21         sb.AppendFormat("Content-Type: image/png\r\n");
22         sb.AppendFormat("\r\n");
23     
24         byte[] fileBytes = File.ReadAllBytes(kvp.Value);
25         request.ContentLength += fileBytes.Length;
26     
27         using (Stream requestStream = request.GetRequestStream())
28         {
29             requestStream.Write(Encoding.UTF8.GetBytes(sb.ToString()), 0, sb.Length);
30             requestStream.Write(fileBytes, 0, fileBytes.Length);
31             requestStream.Write(Encoding.UTF8.GetBytes("\r\n"), 0, 2);
32     
33             // 发送请求并返回响应
34             using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
35             using (StreamReader sr = new StreamReader(response.GetResponseStream()))
36             {
37                 return sr.ReadToEnd();
38             }
39         }
40     }
41 }

调用示例：

1 string url = "http://example.com/upload";
2 Dictionary<string, string> parameters = new Dictionary<string, string>();
3 parameters["username"] = "user123";
4 parameters["password"] = "123456";
5 Dictionary<string, string> files = new Dictionary<string, string>();
6 files["avatar"] = @"C:\avatar.png";
7 string result = HttpPost(url, parameters, files);

测试结果：

底层示例数据：

另外方法：