代码很简单，就不罗唆了。
c#：
<%@ page language="c#" autoeventwireup="true" %>
<!doctype html public "-//w3c//dtd xhtml 1.0 transitional//en" "http://www.w3.org/tr/xhtml1/dtd/xhtml1-transitional.dtd">
<script runat="server">
protected void btnupload_click( object sender, eventargs e )
{
if (fileupload1.postedfile.inputstream.length < 1)
{
msg.text = "请选择文件。";
return;
}
string filename = fileupload1.filename;
if (filename.tolower().indexof(".txt") == -1)
{
msg.text = "请选择文本文件。";
return;
}
int filelen = fileupload1.postedfile.contentlength;
byte[] input = new byte[filelen];
system.io.stream uploadstream = fileupload1.postedfile.inputstream;
uploadstream.read(input, 0, filelen);
uploadstream.position = 0;
system.io.streamreader sr = new system.io.streamreader(uploadstream, system.text.encoding.default);
msg.text = "您上传的文件内容是：<br/><br/>" + sr.readtoend();
sr.close();
uploadstream.close();
uploadstream = null;
sr = null;
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>不经保存，直接读取上传文件的内容</title>
</head>
<body>
<form id="mengxianhui" runat="server">
<asp:fileupload id="fileupload1" runat="server" />
<asp:button id="btnupload" runat="server" text="上传" onclick="btnupload_click"></asp:button>
<p>
<asp:label id="msg" runat="server" forecolor="red"></asp:label></p>
</form>
</body>
</html>
