关于Multipart message的格式,可以参考W3C的网站,本文集中演示怎样用C#代码实现该类消息的传送。
[code:c#]
public static class FormUpload
{
public static HttpWebResponse MultipartFormDataPost(string postUrl, string userAgent, Dictionary<string, object> postParameters)
{
string formDataBoundary = “—————————–28947758029299”;
string contentType = “multipart/form-data; boundary=” + formDataBoundary;
byte[] formData = GetMultipartFormData(postParameters, formDataBoundary);
return PostForm(postUrl, userAgent, contentType, formData);
}
private static HttpWebResponse PostForm(string postUrl, string userAgent, string contentType, byte[] formData)
{
HttpWebRequest request = WebRequest.Create(postUrl) as HttpWebRequest;
if (request == null)
{
throw new NullReferenceException(“request is not a http request”);
}
// Set up the request properties
request.Method = “POST”;
request.ContentType = contentType;
request.UserAgent = userAgent;
request.CookieContainer = new CookieContainer();
request.ContentLength = formData.Length; // We need to count how many bytes we’re sending.
using (Stream requestStream = request.GetRequestStream())
{
// Push it out there
requestStream.Write(formData, 0, formData.Length);
requestStream.Close();
}
return request.GetResponse() as HttpWebResponse;
}
private static byte[] GetMultipartFormData(Dictionary<string, object> postParameters, string boundary)
{
Stream formDataStream = new System.IO.MemoryStream();
Encoding encoding = Encoding.Default;
foreach (var param in postParameters)
{
if (param.Value is byte[])
{
byte[] fileData = param.Value as byte[];
// Add just the first part of this param, since we will write the file data directly to the Stream
string header = string.Format(“–{0}\r\nContent-Disposition: form-data; name=\”{1}\”; filename=\”{2}\”;\r\nContent-Type: application/octet-stream\r\n\r\n”, boundary, param.Key, param.Key);
formDataStream.Write(encoding.GetBytes(header), 0, header.Length);
// Write the file data directly to the Stream, rather than serializing it to a string.
formDataStream.Write(fileData, 0, fileData.Length);
}
else
{
string postData = string.Format(“–{0}\r\nContent-Disposition: form-data; name=\”{1}\”\r\n\r\n{2}\r\n”, boundary, param.Key, param.Value);
formDataStream.Write(encoding.GetBytes(postData), 0, postData.Length);
}
}
// Add the end of the request
string footer = “\r\n–” + boundary + “–\r\n”;
formDataStream.Write(encoding.GetBytes(footer), 0, footer.Length);
// Dump the Stream into a byte[]
formDataStream.Position = 0;
byte[] formData = new byte[formDataStream.Length];
formDataStream.Read(formData, 0, formData.Length);
formDataStream.Close();
return formData;
}
}
[/code]
上面的FormUpload类目的是构造消息,下面就是FormUpload类的调用方法:
[code:c#]
static void Main(string[] args)
{
// Read file data
FileStream fs = new FileStream(“c:\\example.txt”, FileMode.Open, FileAccess.Read);
byte[] data = new byte[fs.Length];
fs.Read(data, 0, data.Length);
fs.Close();
// Generate post objects
Dictionary<string, object> postParameters = new Dictionary<string, object>();
postParameters.Add(“user”, “fdreader”);
postParameters.Add(“pass”, “pl!mnsj@38“);
postParameters.Add(“logfile”, “example.txt”);
postParameters.Add(“example.txt”, data);
// Create request and receive response
string postURL = @”http://bigbird.itsc.cuhk.edu.hk/etickettest/palm/attendance.asp“;
string userAgent = “Someone”;
HttpWebResponse webResponse = FormUpload.MultipartFormDataPost(postURL, userAgent, postParameters);
// Process response
StreamReader responseReader = new StreamReader(webResponse.GetResponseStream());
string fullResponse = responseReader.ReadToEnd();
webResponse.Close();
Console.Write(fullResponse);
Console.ReadKey();
}
[/code]