JSP basics supplement

<Meta HTTP-equiv = "Pragma" Content = "NO-Cache">
<Meta HTTP-equiv = "the Cache-Control" Content = "NO-Cache">
<Meta HTTP-equiv = "the Expires" Content = "0" >
when you clear your browser's cache, which together with a few other, it can make you enter the page has been visited again, ie the browser must download the latest content from the server, to refresh the effect.