本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/codeshark/archive/2008/05/23/2473664.aspx
方式一：TransmitFile实现下载。将指定的文件直接写入 HTTP 响应输出流，而不在内存中缓冲该文件。
protected void Button1_Click(object sender, EventArgs e)
...{
/**//*
微软为Response对象提供了一个新的方法TransmitFile来解决使用Response.BinaryWrite下载超过400mb的文件时导致Aspnet_wp.exe进程回收而无法成功下载的问题。
代码如下：
*/
Response.ContentType = "application/x-zip-compressed";
Response.AddHeader("Content-Disposition", "attachment;filename=CodeShark.zip");
string filename = Server.MapPath("DownLoad/CodeShark.zip");
Response.TransmitFile(filename);
}方式二：WriteFile实现下载，将指定的文件直接写入 HTTP 响应输出流。注意：对大型文件使用此方法时，调用此方法可能导致异常。可以使用此方法的文件大小取决于 Web 服务器的硬件配置。
protected void Button2_Click(object sender, EventArgs e)
...{
string fileName = "CodeShark.zip";//客户端保存的文件名
string filePath = Server.MapPath("DownLoad/CodeShark.doc");//路径
FileInfo fileInfo = new FileInfo(filePath);
Response.Clear();
Response.ClearContent();
Response.ClearHeaders();
Response.AddHeader("Content-Disposition", "attachment;filename=" + fileName);
Response.AddHeader("Content-Length", fileInfo.Length.ToString());
Response.AddHeader("Content-Transfer-Encoding", "binary");
Response.ContentType = "application/octet-stream";
Response.ContentEncoding = System.Text.Encoding.GetEncoding("gb2312");
Response.WriteFile(fileInfo.FullName);
Response.Flush();
Response.End();
}方式三：WriteFile分块下载
protected void Button3_Click(object sender, EventArgs e)
...{
string fileName = "CodeShark.zip";//客户端保存的文件名
string filePath = Server.MapPath("DownLoad/CodeShark.zip");//路径
System.IO.FileInfo fileInfo = new System.IO.FileInfo(filePath);
if (fileInfo.Exists == true)
...{
const long ChunkSize = 102400;//100K 每次读取文件，只读取100Ｋ，这样可以缓解服务器的压力
byte[] buffer = new byte[ChunkSize];
Response.Clear();
System.IO.FileStream iStream = System.IO.File.OpenRead(filePath);
long dataLengthToRead = iStream.Length;//获取下载的文件总大小
Response.ContentType = "application/octet-stream";
Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName));
while (dataLengthToRead > 0 && Response.IsClientConnected)
...{
int lengthRead = iStream.Read(buffer, 0, Convert.ToInt32(ChunkSize));//读取的大小
Response.OutputStream.Write(buffer, 0, lengthRead);
Response.Flush();
dataLengthToRead = dataLengthToRead - lengthRead;
}
Response.Close();
}
}方式四：流方式下载
protected void Button4_Click(object sender, EventArgs e)
...{
string fileName = "CodeShark.zip";//客户端保存的文件名
string filePath = Server.MapPath("DownLoad/CodeShark.zip");//路径
//以字符流的形式下载文件
FileStream fs = new FileStream(filePath, FileMode.Open);
byte[] bytes = new byte[(int)fs.Length];
fs.Read(bytes, 0, bytes.Length);
fs.Close();
Response.ContentType = "application/octet-stream";
//通知浏览器下载文件而不是打开
Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8));
Response.BinaryWrite(bytes);
Response.Flush();
Response.End();
}