Télécharger des fichiers avec HTTPWebrequest (multipart/form-data)

Pris le code ci-dessus et corrigé, car il jette Erreur de Serveur Interne 500. Il y a quelques problèmes avec \r\n mal placé et espaces etc. Appliquer le refactoring avec les flux de mémoire, écrire directement à la demande de flux. Voici le résultat:

    public static void HttpUploadFile(string url, string file, string paramName, string contentType, NameValueCollection nvc) {
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 = (HttpWebRequest)WebRequest.Create(url);
wr.ContentType = "multipart/form-data; boundary=" + boundary;
wr.Method = "POST";
wr.KeepAlive = true;
wr.Credentials = System.Net.CredentialCache.DefaultCredentials;
Stream rs = wr.GetRequestStream();
string formdataTemplate = "Content-Disposition: form-data; name=\"{0}\"\r\n\r\n{1}";
foreach (string key in nvc.Keys)
{
rs.Write(boundarybytes, 0, boundarybytes.Length);
string formitem = string.Format(formdataTemplate, key, nvc[key]);
byte[] formitembytes = System.Text.Encoding.UTF8.GetBytes(formitem);
rs.Write(formitembytes, 0, formitembytes.Length);
}
rs.Write(boundarybytes, 0, boundarybytes.Length);
string headerTemplate = "Content-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"\r\nContent-Type: {2}\r\n\r\n";
string header = string.Format(headerTemplate, paramName, file, contentType);
byte[] headerbytes = System.Text.Encoding.UTF8.GetBytes(header);
rs.Write(headerbytes, 0, headerbytes.Length);
FileStream fileStream = new FileStream(file, FileMode.Open, FileAccess.Read);
byte[] buffer = new byte[4096];
int bytesRead = 0;
while ((bytesRead = fileStream.Read(buffer, 0, buffer.Length)) != 0) {
rs.Write(buffer, 0, bytesRead);
}
fileStream.Close();
byte[] trailer = System.Text.Encoding.ASCII.GetBytes("\r\n--" + boundary + "--\r\n");
rs.Write(trailer, 0, trailer.Length);
rs.Close();
WebResponse wresp = null;
try {
wresp = wr.GetResponse();
Stream stream2 = wresp.GetResponseStream();
StreamReader reader2 = new StreamReader(stream2);
log.Debug(string.Format("File uploaded, server response is: {0}", reader2.ReadToEnd()));
} catch(Exception ex) {
log.Error("Error uploading file", ex);
if(wresp != null) {
wresp.Close();
wresp = null;
}
} finally {
wr = null;
}
}

et d'exemples d'utilisation:

    NameValueCollection nvc = new NameValueCollection();
nvc.Add("id", "TTR");
nvc.Add("btn-submit-photo", "Upload");
HttpUploadFile("http://your.server.com/upload", 
@"C:\test\test.jpg", "file", "image/jpeg", nvc);

Il pourrait être étendu à gérer plusieurs fichiers ou tout simplement l'appeler plusieurs fois pour chaque fichier. Toutefois, il s'adapte à vos besoins.

Mise à JOUR: à l'Aide .NET 4.5 (ou .NET 4.0 par l'ajout de la Microsoft.Net.Http paquet de NuGet) c'est possible sans code externe, d'extensions et de "bas niveau" HTTP manipulation. Voici un exemple:

//Perform the equivalent of posting a form with a filename and two files, in HTML:
//<form action="{url}" method="post" enctype="multipart/form-data">
//    <input type="text" name="filename" />
//    <input type="file" name="file1" />
//    <input type="file" name="file2" />
//</form>
private async Task<System.IO.Stream> UploadAsync(string url, string filename, Stream fileStream, byte [] fileBytes)
{
//Convert each of the three inputs into HttpContent objects
HttpContent stringContent = new StringContent(filename);
//examples of converting both Stream and byte [] to HttpContent objects
//representing input type file
HttpContent fileStreamContent = new StreamContent(fileStream);
HttpContent bytesContent = new ByteArrayContent(fileBytes);
//Submit the form using HttpClient and 
//create form data as Multipart (enctype="multipart/form-data")
using (var client = new HttpClient())
using (var formData = new MultipartFormDataContent()) 
{
//Add the HttpContent objects to the form data
//<input type="text" name="filename" />
formData.Add(stringContent, "filename", "filename");
//<input type="file" name="file1" />
formData.Add(fileStreamContent, "file1", "file1");
//<input type="file" name="file2" />
formData.Add(bytesContent, "file2", "file2");
//Invoke the request to the server
//equivalent to pressing the submit button on
//a form with attributes (action="{url}" method="post")
var response = await client.PostAsync(url, formData);
//ensure the request was a success
if (!response.IsSuccessStatusCode)
{
return null;
}
return await response.Content.ReadAsStreamAsync();
}
}

Basé sur le code fourni ci-dessus, j'ai ajouté le support pour de multiples fichiers et de téléchargement d'un flux directement, sans la nécessité d'avoir un fichier local.

De télécharger des fichiers vers une url spécifique, y compris certains post params procédez de la manière suivante:

RequestHelper.PostMultipart(
"http://www.myserver.com/upload.php", 
new Dictionary<string, object>() {
{ "testparam", "my value" },
{ "file", new FormFile() { Name = "image.jpg", ContentType = "image/jpeg", FilePath = "c:\\temp\\myniceimage.jpg" } },
{ "other_file", new FormFile() { Name = "image2.jpg", ContentType = "image/jpeg", Stream = imageDataStream } },
});

Pour améliorer encore plus l'on pouvait déterminer le nom et le type mime du fichier lui-même.

public class FormFile 
{
public string Name { get; set; }
public string ContentType { get; set; }
public string FilePath { get; set; }
public Stream Stream { get; set; }
}
public class RequestHelper
{
public static string PostMultipart(string url, Dictionary<string, object> parameters) {
string boundary = "---------------------------" + DateTime.Now.Ticks.ToString("x");
byte[] boundaryBytes = System.Text.Encoding.ASCII.GetBytes("\r\n--" + boundary + "\r\n");
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.ContentType = "multipart/form-data; boundary=" + boundary;
request.Method = "POST";
request.KeepAlive = true;
request.Credentials = System.Net.CredentialCache.DefaultCredentials;
if(parameters != null && parameters.Count > 0) {
using(Stream requestStream = request.GetRequestStream()) {
foreach(KeyValuePair<string, object> pair in parameters) {
requestStream.Write(boundaryBytes, 0, boundaryBytes.Length);
if(pair.Value is FormFile) {
FormFile file = pair.Value as FormFile;
string header = "Content-Disposition: form-data; name=\"" + pair.Key + "\"; filename=\"" + file.Name + "\"\r\nContent-Type: " + file.ContentType + "\r\n\r\n";
byte[] bytes = System.Text.Encoding.UTF8.GetBytes(header);
requestStream.Write(bytes, 0, bytes.Length);
byte[] buffer = new byte[32768];
int bytesRead;
if(file.Stream == null) {
//upload from file
using(FileStream fileStream = File.OpenRead(file.FilePath)) {
while((bytesRead = fileStream.Read(buffer, 0, buffer.Length)) != 0)
requestStream.Write(buffer, 0, bytesRead);
fileStream.Close();
}
}
else {
//upload from given stream
while((bytesRead = file.Stream.Read(buffer, 0, buffer.Length)) != 0)
requestStream.Write(buffer, 0, bytesRead);
}
}
else {
string data = "Content-Disposition: form-data; name=\"" + pair.Key + "\"\r\n\r\n" + pair.Value;
byte[] bytes = System.Text.Encoding.UTF8.GetBytes(data);
requestStream.Write(bytes, 0, bytes.Length);
}
}
byte[] trailer = System.Text.Encoding.ASCII.GetBytes("\r\n--" + boundary + "--\r\n");
requestStream.Write(trailer, 0, trailer.Length);
requestStream.Close();
}
}
using(WebResponse response = request.GetResponse()) {
using(Stream responseStream = response.GetResponseStream())
using(StreamReader reader = new StreamReader(responseStream))
return reader.ReadToEnd();
}
}
}

A pris le dessus et l'a modifié accepter certaines valeurs d'en-tête, et plusieurs fichiers

    NameValueCollection headers = new NameValueCollection();
headers.Add("Cookie", "name=value;");
headers.Add("Referer", "http://google.com");
NameValueCollection nvc = new NameValueCollection();
nvc.Add("name", "value");
HttpUploadFile(url, new string[] { "c:\\file1.txt", "c:\\file2.jpg" }, new string[] { "file", "image" }, new string[] { "application/octet-stream", "image/jpeg" }, nvc, headers);

public static void HttpUploadFile(string url, string[] file, string[] paramName, string[] contentType, NameValueCollection nvc, NameValueCollection headerItems)
{
//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 = (HttpWebRequest)WebRequest.Create(url);
foreach (string key in headerItems.Keys)
{
if (key == "Referer")
{
wr.Referer = headerItems[key];
}
else
{
wr.Headers.Add(key, headerItems[key]);
}
}
wr.ContentType = "multipart/form-data; boundary=" + boundary;
wr.Method = "POST";
wr.KeepAlive = true;
wr.Credentials = System.Net.CredentialCache.DefaultCredentials;
Stream rs = wr.GetRequestStream();
string formdataTemplate = "Content-Disposition: form-data; name=\"{0}\"\r\n\r\n{1}";
foreach (string key in nvc.Keys)
{
rs.Write(boundarybytes, 0, boundarybytes.Length);
string formitem = string.Format(formdataTemplate, key, nvc[key]);
byte[] formitembytes = System.Text.Encoding.UTF8.GetBytes(formitem);
rs.Write(formitembytes, 0, formitembytes.Length);
}
rs.Write(boundarybytes, 0, boundarybytes.Length);
string headerTemplate = "Content-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"\r\nContent-Type: {2}\r\n\r\n";
string header = "";
for(int i =0; i<file.Count();i++)
{
header = string.Format(headerTemplate, paramName[i], System.IO.Path.GetFileName(file[i]), contentType[i]);
byte[] headerbytes = System.Text.Encoding.UTF8.GetBytes(header);
rs.Write(headerbytes, 0, headerbytes.Length);
FileStream fileStream = new FileStream(file[i], FileMode.Open, FileAccess.Read);
byte[] buffer = new byte[4096];
int bytesRead = 0;
while ((bytesRead = fileStream.Read(buffer, 0, buffer.Length)) != 0)
{
rs.Write(buffer, 0, bytesRead);
}
fileStream.Close();
rs.Write(boundarybytes, 0, boundarybytes.Length);
}
rs.Close();
WebResponse wresp = null;
try
{
wresp = wr.GetResponse();
Stream stream2 = wresp.GetResponseStream();
StreamReader reader2 = new StreamReader(stream2);
//log.Debug(string.Format("File uploaded, server response is: {0}", reader2.ReadToEnd()));
}
catch (Exception ex)
{
//log.Error("Error uploading file", ex);
wresp.Close();
wresp = null;
}
finally
{
wr = null;
}
}

Exemple VB (convertie à partir d'exemple en C# sur un autre post):

Private Sub HttpUploadFile( _
ByVal uri As String, _
ByVal filePath As String, _
ByVal fileParameterName As String, _
ByVal contentType As String, _
ByVal otherParameters As Specialized.NameValueCollection)
Dim boundary As String = "---------------------------" & DateTime.Now.Ticks.ToString("x")
Dim newLine As String = System.Environment.NewLine
Dim boundaryBytes As Byte() = Text.Encoding.ASCII.GetBytes(newLine & "--" & boundary & newLine)
Dim request As Net.HttpWebRequest = Net.WebRequest.Create(uri)
request.ContentType = "multipart/form-data; boundary=" & boundary
request.Method = "POST"
request.KeepAlive = True
request.Credentials = Net.CredentialCache.DefaultCredentials
Using requestStream As IO.Stream = request.GetRequestStream()
Dim formDataTemplate As String = "Content-Disposition: form-data; name=""{0}""{1}{1}{2}"
For Each key As String In otherParameters.Keys
requestStream.Write(boundaryBytes, 0, boundaryBytes.Length)
Dim formItem As String = String.Format(formDataTemplate, key, newLine, otherParameters(key))
Dim formItemBytes As Byte() = Text.Encoding.UTF8.GetBytes(formItem)
requestStream.Write(formItemBytes, 0, formItemBytes.Length)
Next key
requestStream.Write(boundaryBytes, 0, boundaryBytes.Length)
Dim headerTemplate As String = "Content-Disposition: form-data; name=""{0}""; filename=""{1}""{2}Content-Type: {3}{2}{2}"
Dim header As String = String.Format(headerTemplate, fileParameterName, filePath, newLine, contentType)
Dim headerBytes As Byte() = Text.Encoding.UTF8.GetBytes(header)
requestStream.Write(headerBytes, 0, headerBytes.Length)
Using fileStream As New IO.FileStream(filePath, IO.FileMode.Open, IO.FileAccess.Read)
Dim buffer(4096) As Byte
Dim bytesRead As Int32 = fileStream.Read(buffer, 0, buffer.Length)
Do While (bytesRead > 0)
requestStream.Write(buffer, 0, bytesRead)
bytesRead = fileStream.Read(buffer, 0, buffer.Length)
Loop
End Using
Dim trailer As Byte() = Text.Encoding.ASCII.GetBytes(newLine & "--" + boundary + "--" & newLine)
requestStream.Write(trailer, 0, trailer.Length)
End Using
Dim response As Net.WebResponse = Nothing
Try
response = request.GetResponse()
Using responseStream As IO.Stream = response.GetResponseStream()
Using responseReader As New IO.StreamReader(responseStream)
Dim responseText = responseReader.ReadToEnd()
Diagnostics.Debug.Write(responseText)
End Using
End Using
Catch exception As Net.WebException
response = exception.Response
If (response IsNot Nothing) Then
Using reader As New IO.StreamReader(response.GetResponseStream())
Dim responseText = reader.ReadToEnd()
Diagnostics.Debug.Write(responseText)
End Using
response.Close()
End If
Finally
request = Nothing
End Try
End Sub

Il est un autre exemple de travail avec certains de mes commentaires :

        List<MimePart> mimeParts = new List<MimePart>();
try
{
foreach (string key in form.AllKeys)
{
StringMimePart part = new StringMimePart();
part.Headers["Content-Disposition"] = "form-data; name=\"" + key + "\"";
part.StringData = form[key];
mimeParts.Add(part);
}
int nameIndex = 0;
foreach (UploadFile file in files)
{
StreamMimePart part = new StreamMimePart();
if (string.IsNullOrEmpty(file.FieldName))
file.FieldName = "file" + nameIndex++;
part.Headers["Content-Disposition"] = "form-data; name=\"" + file.FieldName + "\"; filename=\"" + file.FileName + "\"";
part.Headers["Content-Type"] = file.ContentType;
part.SetStream(file.Data);
mimeParts.Add(part);
}
string boundary = "----------" + DateTime.Now.Ticks.ToString("x");
req.ContentType = "multipart/form-data; boundary=" + boundary;
req.Method = "POST";
long contentLength = 0;
byte[] _footer = Encoding.UTF8.GetBytes("--" + boundary + "--\r\n");
foreach (MimePart part in mimeParts)
{
contentLength += part.GenerateHeaderFooterData(boundary);
}
req.ContentLength = contentLength + _footer.Length;
byte[] buffer = new byte[8192];
byte[] afterFile = Encoding.UTF8.GetBytes("\r\n");
int read;
using (Stream s = req.GetRequestStream())
{
foreach (MimePart part in mimeParts)
{
s.Write(part.Header, 0, part.Header.Length);
while ((read = part.Data.Read(buffer, 0, buffer.Length)) > 0)
s.Write(buffer, 0, read);
part.Data.Dispose();
s.Write(afterFile, 0, afterFile.Length);
}
s.Write(_footer, 0, _footer.Length);
}
return (HttpWebResponse)req.GetResponse();
}
catch
{
foreach (MimePart part in mimeParts)
if (part.Data != null)
part.Data.Dispose();
throw;
}

Et il est un exemple de l'aide :

            UploadFile[] files = new UploadFile[] 
{ 
new UploadFile(@"C:\2.jpg","new_file","image/jpeg") //new_file is id of upload field
};
NameValueCollection form = new NameValueCollection();
form["id_hidden_input"] = "value_hidden_inpu"; //there is additional param (hidden fields on page)
HttpWebRequest req = (HttpWebRequest)WebRequest.Create(full URL of action);
//set credentials/cookies etc. 
req.CookieContainer = hrm.CookieContainer; //hrm is my class. i copied all cookies from last request to current (for auth)
HttpWebResponse resp = HttpUploadHelper.Upload(req, files, form);
using (Stream s = resp.GetResponseStream())
using (StreamReader sr = new StreamReader(s))
{
string response = sr.ReadToEnd();
}
//profit!

Modifié @CristianRomanescu code pour travailler avec des flux de mémoire, accepter de fichier comme un tableau d'octets, autoriser les valeurs null de la cnv, de la demande de retour de réponse et de travailler avec l'Autorisation de l'en-tête. Testé le code avec l'Api Web 2.

private string HttpUploadFile(string url, byte[] file, string fileName, string paramName, string contentType, NameValueCollection nvc, string authorizationHeader)
{
string boundary = "---------------------------" + DateTime.Now.Ticks.ToString("x");
byte[] boundarybytes = System.Text.Encoding.ASCII.GetBytes("\r\n--" + boundary + "\r\n");
HttpWebRequest wr = (HttpWebRequest)WebRequest.Create(url);
wr.ContentType = "multipart/form-data; boundary=" + boundary;
wr.Method = "POST";
wr.Headers.Add("Authorization", authorizationHeader);
wr.KeepAlive = true;
Stream rs = wr.GetRequestStream();
string formdataTemplate = "Content-Disposition: form-data; name=\"{0}\"\r\n\r\n{1}";
if (nvc != null)
{
foreach (string key in nvc.Keys)
{
rs.Write(boundarybytes, 0, boundarybytes.Length);
string formitem = string.Format(formdataTemplate, key, nvc[key]);
byte[] formitembytes = System.Text.Encoding.UTF8.GetBytes(formitem);
rs.Write(formitembytes, 0, formitembytes.Length);
}
}
rs.Write(boundarybytes, 0, boundarybytes.Length);
string headerTemplate = "Content-Disposition: form-data; name=\"{0}\"; filename=\"{1}\"\r\nContent-Type: {2}\r\n\r\n";
string header = string.Format(headerTemplate, paramName, fileName, contentType);
byte[] headerbytes = System.Text.Encoding.UTF8.GetBytes(header);
rs.Write(headerbytes, 0, headerbytes.Length);
rs.Write(file, 0, file.Length);
byte[] trailer = System.Text.Encoding.ASCII.GetBytes("\r\n--" + boundary + "--\r\n");
rs.Write(trailer, 0, trailer.Length);
rs.Close();
WebResponse wresp = null;
try
{
wresp = wr.GetResponse();
Stream stream2 = wresp.GetResponseStream();
StreamReader reader2 = new StreamReader(stream2);
var response = reader2.ReadToEnd();
return response;
}
catch (Exception ex)
{
if (wresp != null)
{
wresp.Close();
wresp = null;
}
return null;
}
finally
{
wr = null;
}
}

Testcode:

[HttpPost]
[Route("postformdata")]
public IHttpActionResult PostFormData()
{
//Check if the request contains multipart/form-data.
if (!Request.Content.IsMimeMultipartContent())
{
throw new HttpResponseException(HttpStatusCode.UnsupportedMediaType);
}
var provider = new MultipartMemoryStreamProvider();
try
{
//Read the form data.
var result = Request.Content.ReadAsMultipartAsync(provider).Result;
string response = "";
//This illustrates how to get the file names.
foreach (var file in provider.Contents)
{
var fileName = file.Headers.ContentDisposition.FileName.Trim('\"');
var buffer =  file.ReadAsByteArrayAsync().Result;
response = HttpUploadFile("https://localhost/api/v1/createfromfile", buffer, fileName, "file", "application/pdf", null, "AuthorizationKey");
}
return Ok(response);
}
catch (System.Exception e)
{
return InternalServerError();
}
}

J'ai écrit une classe à l'aide WebClient chemin du retour quand le faire en plusieurs parties formulaire de téléchargement.

http://ferozedaud.blogspot.com/2010/03/multipart-form-upload-helper.html

///
///MimePart
///Abstract class for all MimeParts
///
abstract class MimePart
{
public string Name { get; set; }
public abstract string ContentDisposition { get; }
public abstract string ContentType { get; }
public abstract void CopyTo(Stream stream);
public String Boundary
{
get;
set;
}
}
class NameValuePart : MimePart
{
private NameValueCollection nameValues;
public NameValuePart(NameValueCollection nameValues)
{
this.nameValues = nameValues;
}
public override void CopyTo(Stream stream)
{
string boundary = this.Boundary;
StringBuilder sb = new StringBuilder();
foreach (object element in this.nameValues.Keys)
{
sb.AppendFormat("--{0}", boundary);
sb.Append("\r\n");
sb.AppendFormat("Content-Disposition: form-data; name=\"{0}\";", element);
sb.Append("\r\n");
sb.Append("\r\n");
sb.Append(this.nameValues[element.ToString()]);
sb.Append("\r\n");
}
sb.AppendFormat("--{0}", boundary);
sb.Append("\r\n");
//Trace.WriteLine(sb.ToString());
byte [] data = Encoding.ASCII.GetBytes(sb.ToString());
stream.Write(data, 0, data.Length);
}
public override string ContentDisposition
{
get { return "form-data"; }
}
public override string ContentType
{
get { return String.Empty; }
}
} 
class FilePart : MimePart
{
private Stream input;
private String contentType;
public FilePart(Stream input, String name, String contentType)
{
this.input = input;
this.contentType = contentType;
this.Name = name;
}
public override void CopyTo(Stream stream)
{
StringBuilder sb = new StringBuilder();
sb.AppendFormat("Content-Disposition: {0}", this.ContentDisposition);
if (this.Name != null)
sb.Append("; ").AppendFormat("name=\"{0}\"", this.Name);
if (this.FileName != null)
sb.Append("; ").AppendFormat("filename=\"{0}\"", this.FileName);
sb.Append("\r\n");
sb.AppendFormat(this.ContentType);
sb.Append("\r\n");
sb.Append("\r\n");
//serialize the header data.
byte[] buffer = Encoding.ASCII.GetBytes(sb.ToString());
stream.Write(buffer, 0, buffer.Length);
//send the stream.
byte[] readBuffer = new byte[1024];
int read = input.Read(readBuffer, 0, readBuffer.Length);
while (read > 0)
{
stream.Write(readBuffer, 0, read);
read = input.Read(readBuffer, 0, readBuffer.Length);
}
//write the terminating boundary
sb.Length = 0;
sb.Append("\r\n");
sb.AppendFormat("--{0}", this.Boundary);
sb.Append("\r\n");
buffer = Encoding.ASCII.GetBytes(sb.ToString());
stream.Write(buffer, 0, buffer.Length);
}
public override string ContentDisposition
{
get { return "file"; }
}
public override string ContentType
{
get { 
return String.Format("content-type: {0}", this.contentType); 
}
}
public String FileName { get; set; }
}
///
///Helper class that encapsulates all file uploads
///in a mime part.
///
class FilesCollection : MimePart
{
private List files;
public FilesCollection()
{
this.files = new List();
this.Boundary = MultipartHelper.GetBoundary();
}
public int Count
{
get { return this.files.Count; }
}
public override string ContentDisposition
{
get
{
return String.Format("form-data; name=\"{0}\"", this.Name);
}
}
public override string ContentType
{
get { return String.Format("multipart/mixed; boundary={0}", this.Boundary); }
}
public override void CopyTo(Stream stream)
{
//serialize the headers
StringBuilder sb = new StringBuilder(128);
sb.Append("Content-Disposition: ").Append(this.ContentDisposition).Append("\r\n");
sb.Append("Content-Type: ").Append(this.ContentType).Append("\r\n");
sb.Append("\r\n");
sb.AppendFormat("--{0}", this.Boundary).Append("\r\n");
byte[] headerBytes = Encoding.ASCII.GetBytes(sb.ToString());
stream.Write(headerBytes, 0, headerBytes.Length);
foreach (FilePart part in files)
{
part.Boundary = this.Boundary;
part.CopyTo(stream);
}
}
public void Add(FilePart part)
{
this.files.Add(part);
}
}
///
///Helper class to aid in uploading multipart
///entities to HTTP web endpoints.
///
class MultipartHelper
{
private static Random random = new Random(Environment.TickCount);
private List formData = new List();
private FilesCollection files = null;
private MemoryStream bufferStream = new MemoryStream();
private string boundary;
public String Boundary { get { return boundary; } }
public static String GetBoundary()
{
return Environment.TickCount.ToString("X");
}
public MultipartHelper()
{
this.boundary = MultipartHelper.GetBoundary();
}
public void Add(NameValuePart part)
{
this.formData.Add(part);
part.Boundary = boundary;
}
public void Add(FilePart part)
{
if (files == null)
{
files = new FilesCollection();
}
this.files.Add(part);
}
public void Upload(WebClient client, string address, string method)
{
//set header
client.Headers.Add(HttpRequestHeader.ContentType, "multipart/form-data; boundary=" + this.boundary);
Trace.WriteLine("Content-Type: multipart/form-data; boundary=" + this.boundary + "\r\n");
//first, serialize the form data
foreach (NameValuePart part in this.formData)
{
part.CopyTo(bufferStream);
}
//serialize the files.
this.files.CopyTo(bufferStream);
if (this.files.Count > 0)
{
//add the terminating boundary.
StringBuilder sb = new StringBuilder();
sb.AppendFormat("--{0}", this.Boundary).Append("\r\n");
byte [] buffer = Encoding.ASCII.GetBytes(sb.ToString());
bufferStream.Write(buffer, 0, buffer.Length);
}
bufferStream.Seek(0, SeekOrigin.Begin);
Trace.WriteLine(Encoding.ASCII.GetString(bufferStream.ToArray()));
byte [] response = client.UploadData(address, method, bufferStream.ToArray());
Trace.WriteLine("----- RESPONSE ------");
Trace.WriteLine(Encoding.ASCII.GetString(response));
}
///
///Helper class that encapsulates all file uploads
///in a mime part.
///
class FilesCollection : MimePart
{
private List files;
public FilesCollection()
{
this.files = new List();
this.Boundary = MultipartHelper.GetBoundary();
}
public int Count
{
get { return this.files.Count; }
}
public override string ContentDisposition
{
get
{
return String.Format("form-data; name=\"{0}\"", this.Name);
}
}
public override string ContentType
{
get { return String.Format("multipart/mixed; boundary={0}", this.Boundary); }
}
public override void CopyTo(Stream stream)
{
//serialize the headers
StringBuilder sb = new StringBuilder(128);
sb.Append("Content-Disposition: ").Append(this.ContentDisposition).Append("\r\n");
sb.Append("Content-Type: ").Append(this.ContentType).Append("\r\n");
sb.Append("\r\n");
sb.AppendFormat("--{0}", this.Boundary).Append("\r\n");
byte[] headerBytes = Encoding.ASCII.GetBytes(sb.ToString());
stream.Write(headerBytes, 0, headerBytes.Length);
foreach (FilePart part in files)
{
part.Boundary = this.Boundary;
part.CopyTo(stream);
}
}
public void Add(FilePart part)
{
this.files.Add(part);
}
}
}
class Program
{
static void Main(string[] args)
{
Trace.Listeners.Add(new ConsoleTraceListener());
try
{
using (StreamWriter sw = new StreamWriter("testfile.txt", false))
{
sw.Write("Hello there!");
}
using (Stream iniStream = File.OpenRead(@"c:\platform.ini"))
using (Stream fileStream = File.OpenRead("testfile.txt"))
using (WebClient client = new WebClient())
{
MultipartHelper helper = new MultipartHelper();
NameValueCollection props = new NameValueCollection();
props.Add("fname", "john");
props.Add("id", "acme");
helper.Add(new NameValuePart(props));
FilePart filepart = new FilePart(fileStream, "pics1", "text/plain");
filepart.FileName = "1.jpg";
helper.Add(filepart);
FilePart ini = new FilePart(iniStream, "pics2", "text/plain");
ini.FileName = "inifile.ini";
helper.Add(ini);
helper.Upload(client, "http://localhost/form.aspx", "POST");
}
}
catch (Exception e)
{
Trace.WriteLine(e);
}
}
}

Cela fonctionne avec toutes les versions de la .NET framework.