基于HTTP的上载和下载

基于http流上载：
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private void cmdSendFileData_Click(object sender, System.EventArgs e)
{
// This method takes a local file named datafile.txt and sends its
// contents via a WebRequest to a website. The contents are sent via
// HTTP using the Request stream of the WebRequest object. The file
// is accessed using a FileStream.
string strMsg = "In order to run this part of the sample, you must adjust the security settings" +
" for the physical directory that contains the ASPX files." + Environment.NewLine + Environment.NewLine +
"Please see the Readthis.htm file for more information." + Environment.NewLine +
"Also see the source code (for the procedure cmdSendFileData_Click) to remove this warning after the security settings have been adjusted.";

FileStream fs = null; //' To access the local file;
WebRequest req = null; //' Reference to the Webrequest;
// Wrap the stream access in a try {/Finally block to guarantee a timely
// release of the stream resources.

try
{
// Access the file
fs = new FileStream("..//..//DataFile.txt", FileMode.Open);
// Create the WebRequest instance
req = WebRequest.Create("http://localhost/SendAndReceiveDataWebPages/SendData.aspx");
// Use POST since we're sending content in the body.
req.Method = "POST";
// Copy from the file into the RequestStream
CopyData(fs, req.GetRequestStream());
}
catch( Exception exp)
{
MessageBox.Show(exp.Message, this.Text, MessageBoxButtons.OK, MessageBoxIcon.Error);
return;
}
finally
{
try
{
// Guarantee the streams will be closed
if (req != null) req.GetRequestStream().Close();
if (fs != null) fs.Close();
}
catch
{
// Eat the error if we get one
}
}

WebResponse rsp = null;

try
{
// This actually sends the data to the Web Server
rsp = req.GetResponse();
if (Convert.ToDouble(rsp.Headers["Content-Length"]) == 0)
{
MessageBox.Show("Data Sent Sucessfully.", this.Text, MessageBoxButtons.OK, MessageBoxIcon.Information);
}
}
catch( Exception exp)
{
MessageBox.Show(exp.Message, this.Text, MessageBoxButtons.OK, MessageBoxIcon.Error);
}
finally
{
try
{
if ( rsp != null) rsp.Close();
}
catch{
}
}
}   
    
    基于http流下载：
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private void cmdReceiveDataFile_Click(object sender, System.EventArgs e)
{
// This method requests and receives an XML file from a website.
// The file is streamed back to this method, which copies the contents
// into a local file named ReceivedXMLFile.xml. The contents are streamed
// using the ResponseStream of the WebResponse class. The stream access
// is wrapped in try {/catch blocks to ensure timely release of the
// resources.
string strMsg = "In order to run this part of the sample, you must adjust the security settings" +
" for the physical directory that contains the ASPX files." + Environment.NewLine + Environment.NewLine +
"Please see the Readthis.htm file for more information." + Environment.NewLine +
"Also see the source code (for the procedure cmdReceiveImageFile_Click) to remove this warning after the security settings have been adjusted.";

FileStream fs = null; //' To access the local file;
WebRequest req;
StreamReader sr;

try
{
// This sets up the Request instance
req = WebRequest.Create("http://localhost/SendAndReceiveDataWebPages/ReceiveData.aspx");
// Use a GET since no data is being sent to the web server
req.Method = "GET";
// This causes the round-trip
WebResponse rsp = req.GetResponse();
try
{
// Open the file to stream in the content
fs = new FileStream("ReceivedFile.rar", FileMode.Create);
// Copy the content from the response stream to the file.
CopyData(rsp.GetResponseStream(), fs);
}
catch( Exception exp)
{
// Will catch any error that we're not explicitly trapping.
MessageBox.Show(exp.Message, this.Text, MessageBoxButtons.OK, MessageBoxIcon.Stop);
}
finally
{
// Guarantee the streams will be closed
if (rsp != null) rsp.GetResponseStream().Close();
if (fs != null) fs.Close();
}
MessageBox.Show("Receive of data file completed successfully!", this.Text, MessageBoxButtons.OK, MessageBoxIcon.Information);
}
catch( Exception exp)
{
// Will catch any error that we're not explicitly trapping.
MessageBox.Show(exp.Message, this.Text, MessageBoxButtons.OK, MessageBoxIcon.Stop);
}
}

--------------------------
方法：
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private void CopyData(Stream FromStream, Stream ToStream)
{
// This routine copies content from one stream to another, regardless
// of the media represented by the stream.
// This will track the # bytes read from the FromStream
int intBytesRead;
// The maximum size of each read
const int intSize = 4096;
Byte[] bytes = new Byte[intSize];
// Read the first bit of content, then write and read all the content
// From the FromStream to the ToStream.
intBytesRead = FromStream.Read(bytes, 0, intSize);

while (intBytesRead > 0)
{
ToStream.Write(bytes, 0, intBytesRead);
intBytesRead = FromStream.Read(bytes, 0, intSize);
}

}