使用JQuery的validate插件做客户端验证非常方便，下面做一个使用validate插件验证用户注册信息的例子。
本实例使用的是1.5版本。
示例是在SSH下做的，代码如下：
registe.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>注册页面</title>
<mce:script type="text/javascript" src="js/jquery.1.4.2.js" mce_src="js/jquery.1.4.2.js"></mce:script>
<mce:script type="text/javascript" src="js/validate/jquery.validate.js" mce_src="js/validate/jquery.validate.js"></mce:script>
<link href="js/validate/jquery.validate.css" mce_href="js/validate/jquery.validate.css" type="text/css" rel="stylesheet"/>
<mce:script type="text/javascript"><!--
//扩展validator的校验方法
$.validator.addMethod("onlyLetterAndDigit",function(value, element, params){
var regex=new RegExp('^[0-9a-zA-Z]+$');
return regex.test(value);
},"只能输入字母或数字");
$(function(){
$("#registe").validate({
//定义验证规则,其中属性名为表单的name属性
rules:{
username:{
required:true,
onlyLetterAndDigit:true,//使用自定义方法限制只能输入字母或数字
rangelength:[4,20],
remote:"registe!validName.action"//使用AJAX异步校验
},
password:{
required:true,
rangelength:[4,20]
},
chkpassword:{
required:true,
equalTo:"#password"
},
email:{
required:true,
email:true
},
vercode:"required"
},
messages:{
username:{
required:"请输入用户名",
rangelength:"用户名长度必须在4～20位之间",
remote:$.format("用户名{0}已存在，请重新输入！")
},
password:{
required:"请输入密码",
rangelength:"密码长度必须在4～20位之间"
},
chkpassword:{
required:"请再次输入密码",
equalTo:"密码输入不一致，请重新输入"
},
email:{
required:"请输入电子邮件",
email:"请输入合法的电子邮件"
},
vercode:{
required:"请输入验证码"
}
}
});
});
//刷新验证码
function refresh()
{
$("#authImg").src="authImg?now="+new Date();
}
// --></mce:script>
</head>
<body>
<form action="registe.action" method="post" id="registe">
<table>
<caption><h2 id="用户注册">用户注册</h2></caption>
<tr>
<td>用 户 名：</td><td><input type="text" name="username" id="username"/></td>
</tr>
<tr>
<td>密 码：</td><td><input type="text" name="password" id="password"/> </td>
</tr>
<tr>
<td>确认密码：</td><td><input type="text" name="chkpassword"/></td>
</tr>
<tr>
<td>Email：</td><td><input type="text" name="email"/></td>
</tr>
<tr>
<td>验证码：</td><td valign="bottom"><input type="text" name="vercode" size="10"/> <img src="/static/imghwm/default1.png" data-src="authImg" class="lazy" alt="" mce_ id="authImg" align="absmiddle"><a href="#" mce_href="#" onclick="refresh()"><span style="max-width:90%" mce_style="font-size:12px">刷新验证码</span></a></td>
</tr>
<tr>
<td colspan="2"><input type="submit" value="提交"/><input type="reset" value="重填"/></td>
</tr>
</table>
</form>
</body>
</html>
后台RegisteAction.java的主要方法
public String execute() throws Exception {
Map session = ActionContext.getContext().getSession();
String ver2 = (String) session.get("rand");
session.put("rand", null);
//判断验证码是否正确
if (vercode.equals(ver2)) {
if (userManager.validName(username)) {
if (userManager.addUser(username, password, email) > 0)
return SUCCESS;
else
addActionError("注册失败，请重试！");
} else {
addActionError("该用户名已存在，请重新输入！");
}
} else {
addActionError("验证码不匹配，请重新输入");
}
return INPUT;
}
//验证用户名是否可用
public String validName() throws Exception {
System.out.println(username);
boolean flag = userManager.validName(username);
HttpServletResponse response = ServletActionContext.getResponse();
response.setDateHeader("Expires", 0);
response.addHeader("Pragma", "no-cache");
response.setHeader("Cache-Control", "no-cache");
response.setContentType("text/plain;charset=UTF-8");
if (flag)
response.getWriter().write("true");
else
response.getWriter().write("false");
response.getWriter().flush();
// 因为直接输出内容而不经过jsp,因此返回null.
return null;
}
效果图如下：
注意：使用remote异步验证用户名的方法应该通过response.getWriter().write("true")来输出，而不能像普通方法一样返回字符串。
关于插件更详细的介绍可以查看“jQuery validate验证插件使用详解”。
另外，jQuery也支持动态给控件添加校验，例如：
但要注意：如果对集合中的元素动态添加校验需要循环对每个元素添加，这是因为jQuery隐式实现了集合操作，但validate插件没有。例如：
$(".quantity").each(function(){
$(this).rules("add",{digits:true,required:true});
});
以上就是本文的全部内容，希望对大家的学习有所帮助。
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