1. 下载DotNetZip(Ionic.zip.dll)
2. 代码
protected void AllDown_Click(Object sender, EventArgs e)
{
int itemID;
if (Request.QueryString["ItemID"] != null)
{
itemID = int.Parse(Request.QueryString["itemID"].ToString());
SPWeb web = SPContext.Current.Site.OpenWeb("子网站名字");
web.AllowUnsafeUpdates = true;