C# 上傳檔案(防止記憶體溢位)
阿新 • • 發佈:2019-01-04
public static string MyUploader(string strFileToUpload, string strUrl,Action<double,double> uploading)
{
string strFileFormName = "file";
Uri oUri = new Uri(strUrl);
string strBoundary = "----------" + DateTime.Now.Ticks.ToString("x");
// The trailing boundary string
byte[] boundaryBytes = Encoding.ASCII.GetBytes("\r\n--" + strBoundary + "--\r\n");
//**注意此處的 strBoundary後的換行前加上--,不然會異常**
// The post message header
StringBuilder sb = new StringBuilder();
sb.Append("--");
sb.Append(strBoundary);
sb.Append("\r\n");
sb.Append("Content-Disposition: form-data; name=\"");
sb.Append(strFileFormName);
sb.Append("\"; filename=\"" );
sb.Append(Path.GetFileName(strFileToUpload));
sb.Append("\"");
sb.Append("\r\n");
sb.Append("Content-Type: ");
sb.Append("application/octet-stream");
sb.Append("\r\n");
sb.Append("\r\n");
string strPostHeader = sb.ToString();
byte[] postHeaderBytes = Encoding.UTF8.GetBytes(strPostHeader);
// The WebRequest
HttpWebRequest oWebrequest = (HttpWebRequest)WebRequest.Create(oUri);
oWebrequest.ContentType = "multipart/form-data; boundary=" + strBoundary;
oWebrequest.Method = "POST";
// This is important, otherwise the whole file will be read to memory anyway...
oWebrequest.AllowWriteStreamBuffering = false;
// Get a FileStream and set the final properties of the WebRequest
FileStream oFileStream = new FileStream(strFileToUpload, FileMode.Open, FileAccess.Read);
long length = postHeaderBytes.Length + oFileStream.Length + boundaryBytes.Length;
oWebrequest.ContentLength = length;
Stream oRequestStream = oWebrequest.GetRequestStream();
// Write the post header
oRequestStream.Write(postHeaderBytes, 0, postHeaderBytes.Length);
// Stream the file contents in small pieces (4096 bytes, max).
byte[] buffer = new Byte[checked((uint)Math.Min(4096, (int)oFileStream.Length))];
int bytesRead = 0;
double size=0;
while ((bytesRead = oFileStream.Read(buffer, 0, buffer.Length)) != 0)
{
oRequestStream.Write(buffer, 0, bytesRead);
size+=bytesRead;
if(uploading!=null)uploading(length ,size);
}
oFileStream.Close();
// Add the trailing boundary
oRequestStream.Write(boundaryBytes, 0, boundaryBytes.Length);
WebResponse oWResponse = oWebrequest.GetResponse();
Stream s = oWResponse.GetResponseStream();
StreamReader sr = new StreamReader(s);
String sReturnString = sr.ReadToEnd();
// Clean up
oFileStream.Close();
oRequestStream.Close();
s.Close();
sr.Close();
return sReturnString;
}
如果有增加取消功能,可以呼叫oWebrequest的Abort方法取消上傳請求。