在html頭中加入以下3句話,可以防止大部分瀏覽器緩存
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="Cache-Control" content="no-cache, must-revalidate">
<meta http-equiv="expires" content="Wed, 26 Feb 1997 08:21:57 GMT">
<meta http-equiv="Cache-Control" content="no-cache, must-revalidate">
<meta http-equiv="expires" content="Wed, 26 Feb 1997 08:21:57 GMT">
或者js中加入類似下面的代碼,讓每次的鏈接都不一樣
var s=Math.random()*10;
document.getElementById("checkCodeImg").innerHTML="<img src='/checkcode.jsp?rnd="+s+"'/>";
document.getElementById("checkCodeImg").innerHTML="<img src='/checkcode.jsp?rnd="+s+"'/>";