实际上就是拼接 文件头和要传的信息，利用 HttpWebRequest 发送请求即可。 具体的文件头 和要传的信息 其实可以用火狐的工具查看到底发送了哪些东西，格式如何。方法如下，是把别人写的东西改了一点点。参考链接：http://www.cnblogs.com/chiname/articles/375151.html///
/// 上传的方法
///
/// 单个文件名(上传多个文件的方法自己修改)
/// post请求的url
/// post的字符串 键值对，相当于表单上的文本框里的字符
///
public static string UploadFileEx(string uploadfile, string url, NameValueCollection poststring)
{
Uri uri = new Uri(url);
string boundary = "----------" + DateTime.Now.Ticks.ToString("x");
HttpWebRequest webrequest = (HttpWebRequest)WebRequest.Create(uri);
webrequest.ContentType = "multipart/form-data; boundary=" + boundary;
webrequest.Method = "POST";
// Build up the post message header
StringBuilder sb = new StringBuilder();
//加文本
foreach (string key in poststring.Keys)
{
sb.Append("--");
sb.Append(boundary);
sb.Append("\r\n");
sb.Append("Content-Disposition: form-data; name=\"");
sb.Append(key);
sb.Append("\"");
sb.Append("\r\n");
sb.Append("\r\n");
sb.Append(poststring.Get(key));
sb.Append("\r\n");
}
//加文件
sb.Append("--");
sb.Append(boundary);
sb.Append("\r\n");
sb.Append("Content-Disposition: form-data; name=\"filename\";");
sb.Append("filename=\"");
sb.Append(Path.GetFileName(uploadfile));
sb.Append("\"");
sb.Append("\r\n");
sb.Append("Content-Type: multipart/form-data");
sb.Append("\r\n");
sb.Append("\r\n");
string postHeader = sb.ToString();
byte[] postHeaderBytes = Encoding.UTF8.GetBytes(postHeader);
// Build the trailing boundary string as a byte array
// ensuring the boundary appears on a line by itself
byte[] boundaryBytes = Encoding.ASCII.GetBytes("\r\n--" + boundary + "\r\n");
FileStream fileStream = new FileStream(uploadfile, FileMode.Open, FileAccess.Read);
long length = postHeaderBytes.Length + fileStream.Length + boundaryBytes.Length;
webrequest.ContentLength = length;
Stream requestStream = webrequest.GetRequestStream();
// Write out our post header
requestStream.Write(postHeaderBytes, 0, postHeaderBytes.Length);
// Write out the file contents
byte[] buffer = new Byte[checked((uint)Math.Min(4096, (int)fileStream.Length))];
int bytesRead = 0;
while ((bytesRead = fileStream.Read(buffer, 0, buffer.Length)) != 0)
requestStream.Write(buffer, 0, bytesRead);
// Write out the trailing boundary
requestStream.Write(boundaryBytes, 0, boundaryBytes.Length);
webrequest.Timeout = 1000000;
//System.Windows.Forms.MessageBox.Show(webrequest.Timeout.ToString());
WebResponse responce = webrequest.GetResponse();
Stream s = responce.GetResponseStream();
StreamReader sr = new StreamReader(s);
string str = sr.ReadToEnd();
fileStream.Close();
requestStream.Close();
sr.Close();
s.Close();
responce.Close();
return str;
}
实例调用NameValueCollection poststring = new NameValueCollection(); poststring["username"] = "laokaizzz";//post 的参数
poststring["password"] = "111111111";
string uploadfile;// set to file to upload
uploadfile = "D:/2.txt";//上传的文件名
string str = UploadFileEx(uploadfile, http://www.xxx.com/upload", poststring);
MessageBox.Show(str);