说明:
由于showModalDialog缓存严重,下面是在子窗口取消客户端缓存的设置.也可以在服务器端取消缓存,参考:
http://adandelion.cnblogs.com/articles/252137.html
<meta http-equiv="Expires" CONTENT="0">
<meta http-equiv="Cache-Control" CONTENT="no-cache">
<meta http-equiv="Pragma" CONTENT="no-cache">