1.ajax动态验证验证码
验证码:<input type=text name="yzm" onkeyup="checkCode()"/>
<img onclick="changeImg()" style="cursor: pointer;" id="yzmCode" alt="看不清，换一张" src="${pageContext.request.contextpath}/yzm.do"/>
<script> //判断验证码是否正确 function checkCode() { //输入的验证码 var code = document.getElementsByName("yzm")[0].value; //如果长度是4就比较 if (code.length==4) { //1. 创建核心对象 var ajax = null; try { ajax= new XMLHttpRequest(); }catch(e) { ajax = new ActiveXObject("Microsoft.XMLHttp"); } //2. 打开(要偷偷访问谁)并发送 ajax.open("get","${pageContext.request.contextpath}/admin.do?p=checkCode&code="+code+"&x="+Math.random()); ajax.send(null); //3. 接收 ajax.onreadystatechange = function() { //完成且成功 if (ajax.readyState==4 && ajax.status==200) { document.getElementById("yzmDui").style.visibility="visible"; //得到服务器返回的值 var result = ajax.responseText; if ("true"==result) { document.getElementById("yzmDui").src="${pageContext.request.contextpath}/admin/images/dui.png"; } else { document.getElementById("yzmDui").src="${pageContext.request.contextpath}/admin/images/cuo.png"; } } } } } </script>
