Response.ContentType 控制輸出文件類型(討論下載文件問題)
2024-07-21 02:24:13
供稿：網(wǎng)友
服務(wù)器送給客戶端的數(shù)據(jù)包類型可以是text/html文本，也可以是gif/jpeg圖形文件，所以每次傳輸前，我們都必須告知客戶端將要傳輸?shù)奈募愋停话隳J(rèn)情況下為“text/html”類型。
<% response.contenttype = "text/html" %>
<% response.contenttype = "image/gif" %>
<% response.contenttype = "image/jpeg" %>
<% response.contenttype = "text/plain" %>
<% response.contenttype = "image/jpeg" %>
<% response.contenttype = "application/x-cdf" %>
用于作為文本內(nèi)容返回而不是已解釋的 html 語句
response.contenttype = "text/plain"
<%
response.contenttype = "text/plain"
response.write(now()&"會(huì)被執(zhí)行么？")
%>
你可以注意到：頁面提供下載，頁面中的asp內(nèi)容被解釋執(zhí)行了的
程序文件以xls文件被提供下載
response.contenttype = "application/vnd.ms-excel"
<%
response.contenttype = "application/vnd.ms-excel"
response.write("本頁面調(diào)試會(huì)出現(xiàn)下載對(duì)話框提供下載，保存類型為xls")
%>
實(shí)現(xiàn)歌曲連續(xù)播放
response.contenttype="audio/x-pn-realaudio"
<%
dim ramstr
ramstr=""
set rs=server.createobject("adodb.recordset")
sql="xxxxxxxxxxx"
rs.open sql,conn,1,3 'conn已定義
do while not rs.eof
ramstr=ramstr&rs("url")&vbcrlf
rs.movenext
loop
rs.close
response.contenttype="audio/x-pn-realaudio"
'response.contenttype="audio/x-mpegurl"
response.write ramstr
%>
response.write 輸出的時(shí)候，由于定義了response.contenttype 所以輸出歌曲地址的時(shí)候會(huì)自動(dòng)調(diào)用符合相應(yīng)格式的軟件來播放歌曲，不過前提是播放歌曲的軟件必須先安裝的。
以上文章轉(zhuǎn)貼自http://www.w269.com/infow269/1145w2691.htm
這里我想討論一下，這么也東東。
q：如何利用contenttype 來，在服務(wù)器上提供一個(gè).xls后綴的文件點(diǎn)擊下載而不是直接在瀏覽器中打開。（注意：于上程序文件以xls文件被提供下載有所不同）
response.contenttype = "application/x-download"，讓整個(gè)程序文件點(diǎn)擊下載了。怎么辦好呢？？？
a:解決方案1. 利用response.writefile的文件輸出操作
具體在按鈕點(diǎn)擊事件中添加一下代碼
private void btndownload_click(object sender, system.eventargs e)
{
string downloadfilename=server.mappath("file.xls");
string filepath = downloadfilename;
// identify the file name.
string filename = system.io.path.getfilename(filepath);
response.clear();
// specify the type of the downloadable file.
response.contenttype = "application/octet-stream";
// set the default file name in the filedownload dialog box.
response.addheader("content-disposition", "attachment; filename=" + filename);
response.flush();
// download the file.
response.writefile(filepath);
}
以上代碼也適合用于小于100mb的小文件下載
如果是大于100mb的大文件下載可以用response.filestream 。
c#代碼如下：（將 downloadfilename 替換為大于 100 mb 的文件的名稱。）
system.io.stream istream = null;
// buffer to read 10k bytes in chunk:
byte[] buffer = new byte[10000];
// length of the file:
int length;
// total bytes to read:
long datatoread;
// identify the file to download including its path.
string filepath = "downloadfilename";
// identify the file name.
string filename = system.io.path.getfilename(filepath);
try
{
// open the file.
istream = new system.io.filestream(filepath, system.io.filemode.open,
system.io.fileaccess.read,system.io.fileshare.read);//用文件流來處理
// total bytes to read:
datatoread = istream.length;
response.contenttype = "application/octet-stream";//問題就在這里，解決百m關(guān)口
response.addheader("content-disposition", "attachment; filename=" + filename);
// read the bytes.
while (datatoread > 0)
{
// verify that the client is connected.
if (response.isclientconnected)
{
// read the data in buffer.
length = istream.read(buffer, 0, 10000);
// write the data to the current output stream.
response.outputstream.write(buffer, 0, length);
// flush the data to the html output.
response.flush();
buffer= new byte[10000];
datatoread = datatoread - length;
}
else
{
//prevent infinite loop if user disconnects
datatoread = -1;
}
}
}
catch (exception ex)
{
// trap the error, if any.
response.write("error : " + ex.message);
}
finally
{
if (istream != null)
{
//close the file.
istream.close();
}
}
參考：prb：response.writefile 無法下載大文件
http://support.microsoft.com/default.aspx?scid=kb;zh-cn;812406#2
