登录界面
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>静态页面登录测试</title>
<script language="javascript">
window.onload = function() {
createCode()
}
var code; //在全局定义验证码
function createCode() {
code = "";
var codeLength = 4; //验证码的长度
var checkCode = document.getElementById("code");
var random = new Array(0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R',
'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'); //随机数
for(var i = 0; i < codeLength; i++) { //循环操作
var index = Math.floor(Math.random() * 36); //取得随机数的索引（0~35）
code += random[index]; //根据索引取得随机数加到code上
}
checkCode.value = code; //把code值赋给验证码
}
//校验验证码
function validateLogin(){
var sUserName = document.frmLogin.username.value ;
var sPassword = document.frmLogin.password.value ;
var inputCode = document.frmLogin.text_code.value;
/*var sinputCode =document.frmLogin.inputcode.value ; */
if ((sUserName.length <= 0) || (sUserName=="")){
alert("请输入用户名!");
return false ;
}
if ((sPassword.length <= 0) || (sPassword=="")){
alert("请输入密码!");
return false ;
}
if ((inputCode.length<= 0) || (inputCode==NULL)){
alert("请输入验证码!");
return false ;
}
}
</script>
</head>
<body >
<fieldset>
<table background="imagese.jpg " width="933" height="412">
<tr height="170">
<td width="570px"> </td>
<td> </td>
</tr>
<tr>
<td> </td>
<td><table>
<form method ="POST" action="http://localhost:8080/test/hello.html?login=%B5%C7%C2%BC" name="frmLogin" >
<tr>
<td><label for="username">用户名：</label></td>
<td><input type="text" name="username" id="username" placeholder="input your name" size="20" maxlength="20" /></td>
<td > </td>
<td> </td>
</tr>
<tr>
<td><label for="password">密 码：</label></td>
<td><input type="password" name="password" id="password" placeholder="input your password" size="20" maxlength="20" ) this.value='';" /></td>
<td> </td>
<td> </td>
</tr>
<tr>
<td><label for="text_code">验证码:</label></td>
<td><input type="text" size="" name="text_code" id="text_code" /></td>
<td><input type="button" id="code" onclick="createCode()" name=""></td>
</tr>
<tr>
<td><input type="checkbox" name="zlogin" value="1">自动登录</td>
</tr>
</table>
</td>
<tr>
<td> </td>
<td><table>
<tr>
<td><input type="submit" name="login" value="登录" onClick="return validateLogin()"/></td>
<td><input type="reset" name="rs" value="重置"></td>
<td><input type="button" name="button" value="注册" onclick="window.location.href='https://www.w3school.com.cn/jsref/event_onfocus.asp'"></td>
</tr>
</tr>
</table>
</td>
</table>
</fieldset>
</form>
</body>
</html>
借鉴链接：https://blog.csdn.net/kuangqiu/article/details/53483610