c#中通常使用HttpWebRequest进行HTTP网络请求，HttpWebRequest只对Http请求进行了最简单的封装。如果要利用Http协议实现多文件上传，则必须使用POST方法multipart/form-data格式。为了重复使用，我封装了几个方法，实现了多参数文件上传。

添加引用

使用WebRequest需要添加引用System.Web,否则引入出错。

参数封装

方便起见，我把请求参数进行了封装，代码如下:

namespace EasyHttp.Net.Core{ public class KeyValue { public string Key; public string Value; public string FilePath; public string ContentType="*/*"; public KeyValue(string key, string value, string filePath, string contentType) { Key = key; Value = value; FilePath = filePath; ContentType = contentType; } public KeyValue() { } public KeyValue(string key, string value, string filePath) { Key = key; Value = value; FilePath = filePath; } public KeyValue(string key, string value) { Key = key; Value = value; } }}

KeyValue代表了广义的参数，可以是普通的键值对，也可以是文件参数。

多文件上传封装

public static void ExecuteMultipartRequest(HttpWebRequest request, List<KeyValue> nvc){ Console.WriteLine(request.Headers); // log.Debug(string.Format("Uploading {0} to {1}", file, url)); string boundary = "---------------------------" + DateTime.Now.Ticks.ToString("x"); byte[] boundarybytes = System.Text.Encoding.ASCII.GetBytes("\r\n--" + boundary + "\r\n"); HttpWebRequest wr = request; wr.ContentType = "multipart/form-data; boundary=" + boundary; wr.Method = "POST"; wr.KeepAlive = true; wr.Credentials = System.Net.CredentialCache.DefaultCredentials; using (var rs = wr.GetRequestStream()) { // 普通参数模板 string formdataTemplate = "Content-Disposition: form-data; name=\"{0}\"\r\n\r\n{1}"; //带文件的参数模板 string headerTemplate = "Content-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"\r\nContent-Type: {2}\r\n\r\n"; foreach (KeyValue keyValue in nvc) { //如果是普通参数 if (keyValue.FilePath == null) { rs.Write(boundarybytes, 0, boundarybytes.Length); string formitem = string.Format(formdataTemplate, keyValue.Key, keyValue.Value); byte[] formitembytes = System.Text.Encoding.UTF8.GetBytes(formitem); rs.Write(formitembytes, 0, formitembytes.Length); } //如果是文件参数,则上传文件 else { rs.Write(boundarybytes, 0, boundarybytes.Length); string header = string.Format(headerTemplate, keyValue.Key, keyValue.FilePath, keyValue.ContentType); byte[] headerbytes = System.Text.Encoding.UTF8.GetBytes(header); rs.Write(headerbytes, 0, headerbytes.Length); using (var fileStream = new FileStream(keyValue.FilePath, FileMode.Open, FileAccess.Read)) { byte[] buffer = new byte[4096]; int bytesRead = 0; long total = 0; while ((bytesRead = fileStream.Read(buffer, 0, buffer.Length)) != 0) { rs.Write(buffer, 0, bytesRead); total += bytesRead; } } } } byte[] trailer = System.Text.Encoding.ASCII.GetBytes("\r\n--" + boundary + "--\r\n"); rs.Write(trailer, 0, trailer.Length); }}

使用

static void Main(string[] args) { var request = WebRequest.Create("http://localhost:8080/test/upload") as HttpWebRequest; List<KeyValue> keyValues = new List<KeyValue>(); keyValues.Add(new KeyValue("key1","param1")); keyValues.Add(new KeyValue("key2", "param2")); keyValues.Add(new KeyValue("file","test1.png","image/png")); keyValues.Add(new KeyValue("file", "test2.png", "image/png")); EasyHttp.ExecuteMultipartRequest(request,keyValues); }

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