在IHttpHandler中控制下载文件的类型和名称

public   void  ProcessRequest(HttpContext context)
{
    string path = context.Request.QueryString["path"];
    string name = context.Request.QueryString["name"];

    if(path == null || path.Trim() == string.Empty)return;
    path = path.Trim();

    if(name == null || name.Trim() == string.Empty)return;

    if(Path.GetExtension(name).ToLower() != ".xls")
    {
        name += ".xls";
    }

    path = context.Request.ApplicationPath + "/Excel/" + path;

    try
    {
        context.Response.WriteFile(path, false);
        context.Response.ContentType = "application/vnd.ms-excel";
        context.Response.AddHeader("Content-disposition", "inline; filename=" + name);
    }
    catch(Exception ex)
    {
        context.Response.Write(ex.Message);
    }
}

附：MIME类型

csv	application/vnd.ms-excel
css	text/css
js	text/javascript
doc	application/msword
gif	image/gif
bmp	image/bmp
htm	text/html
html	text/html
jpeg	image/jpeg
jpg	image/jpeg
pdf	application/pdf
png	image/png
ppt	application/vnd.ms-powerpoint
rtf	application/msword
txt	text/plain
xls	application/vnd.ms-excel
xml	text/xml
wmv	video/x-ms-wmv
wma	video/x-ms-wmv
mpeg	video/mpeg
mpg	video/mpeg
mpa	video/mpeg
mpe	video/mpeg
mov	video/quicktime
qt	video/quicktime
avi	video/x-msvideo
asf	video/x-ms-asf
asr	video/x-ms-asf
asx	video/x-ms-asf
swf	application/x-shockwave-flash