asp.net中实现文件下载功能
//TransmitFile实现下载
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=z.zip");
string filename = Server.MapPath("DownLoad/aaa.zip");
Response.TransmitFile(filename);
}
//WriteFile实现下载
protected void Button2_Click(object sender, EventArgs e)
{
/*
using System.IO;
*/
string fileName ="aaa.zip";//客户端保存的文件名
string filePath=Server.MapPath("DownLoad/aaa.zip");//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();
}
//WriteFile分块下载
protected void Button3_Click(object sender, EventArgs e)
{
string fileName = "aaa.zip";//客户端保存的文件名
string filePath = Server.MapPath("DownLoad/aaa.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();
}
}
//流方式下载
protected void Button4_Click(object sender, EventArgs e)
{
string fileName = "aaa.zip";//客户端保存的文件名
string filePath = Server.MapPath("DownLoad/aaa.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();
}
------------------------------------------------------------------------------------------------------------
Asp.net中文件上传下载的简单实现
1. 文件下载
在asp.net中,如果想点击某aspx的url实现文件下载只要在其Page_Load函数实现目标url的重定向即可。用下列代码即可实现。
Response.Redirect("ff.zip");
这种方法简便易行,但有一点小问题,就是当要下载的目标文件是浏览器可以打开的类型时,便会在浏览器中打开目标文件。
如当目标文件名为"ff.txt"时,浏览器便会打开"ff.txt"文件,而不是我们想要的文件下载对话框,如何使得任何情况下都能直接下载呢?就需要如下几行代码来帮忙了。
Response.ContentType = "application/octet-stream";
Response.AddHeader("Content-Disposition", "attachment;FileName=" + HttpUtility.UrlEncode("文件名.txt"));
//写入目标文件内容,以下三种方法都可以
Response.WriteFile("ff.txt"); //此处也可以使用@"f:\123.wma"类似的绝对路径(当然也需要相应的权限支持)
//Response.Write("中文abc");
//Response.BinaryWrite(Encoding.ASCII.GetBytes("hello world"));
这两种办法非常有效,但都存在一个问题,那就是断点续传。关于这个问题,感兴趣的朋友可以参看我的下一篇blog。