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();
}