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通常，数据校验在客户端使用javascript来进行的，在这里做的是怎么在服务端使用XML配置文件来校验数据。
1，配置web.xml文件
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0" xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
<display-name></display-name>
<welcome-file-list>
<welcome-file>basicInput.jsp</welcome-file>
</welcome-file-list>
<!-- 配置filter -->
<filter>
<filter-name>struts2</filter-name>
<filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
</filter>
<filter-mapping>
<!-- 拦截所有的URL用户请求 -->
<filter-name>struts2</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>
2，配置struts.xm文件
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
"http://struts.apache.org/dtds/struts-2.3.dtd">
<!-- 配置struts2 -->
<struts>
<!-- 配置包，名称为firstStruts -->
<package name="checkdata" namespace="/" extends="struts-default">
<!-- 配置action -->
<action name="questionAction" class="com.xywei.action.QuestionAction">
<!-- 配置返回结果 -->
<result name="success">success.jsp</result>
<result name="input">basicInput.jsp</result>
<result name="error">error.jsp</result>
</action>
</package>
</struts>
3，编写jsp页面
basicInput.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://"
+ request.getServerName() + ":" + request.getServerPort()
+ path + "/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>数据校验基础</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<b>问题：您最喜欢的颜色是什么？请回答：</b>
<s:form method="post" theme="xhtml" action="questionAction.action" namespace="/"
validate="true">
<s:textfield name="name" label="姓名"></s:textfield>
<s:textfield name="age" label="年龄"></s:textfield>
<s:textfield name="answer" label="回答"></s:textfield>
<s:submit value="提交"></s:submit>
</s:form>
</body>
</html>
success.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme() + "://"
+ request.getServerName() + ":" + request.getServerPort()
+ path + "/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP ‘success.jsp‘ starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
恭喜你，验证成功！！<br>
name:<%=request.getParameter("name")%>
<br> age:<%out.println(request.getParameter("age"));%>
<br> answer:<%out.println(request.getParameter("answer"));%>
<br>
</body>
</html>
error.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP ‘error.jsp‘ starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
信息错误！
</body>
</html>
4,把struts2用到的相关包都放到lib下面
5，配置使用校验数据的XML文件，命名该文件的规则是：Action类-validation.xml，并且要把该文件放入和action同一目录下，如下面处理的action类为QuestionAction，所以就命名处理数据校验的类为QuestionAction-validation.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE validators PUBLIC
"-//Apache Struts//XWork Validator 1.0.2//EN"
"http://struts.apache.org/dtds/xwork-validator-1.0.2.dtd">
<validators>
<field name="name">
<field-validator type="requiredstring">
<message>必须输入姓名</message>
</field-validator>
</field>
<field name="age">
<field-validator type="int">
<param name="min">18</param>
<param name="max">30</param>
<message>年龄只能是18-30岁之间</message>
</field-validator>
</field>
<field name="answer">
<field-validator type="requiredstring">
<message>不能为空！！</message>
</field-validator>
</field>
</validators>
6，编写Action类
QuestionAction.java
package com.xywei.action;
import com.opensymphony.xwork2.ActionSupport;
@SuppressWarnings("serial")
public class QuestionAction extends ActionSupport {
private int age;
private String answer;
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getAnswer() {
return answer;
}
public void setAnswer(String answer) {
this.answer = answer;
}
public String execute() {
if (name.equals("xywei") && age == 23 && answer.equals("wei")) {
return "success";
} else if ((!name.equals("xywei") && !name.equals("")) || (age != 23)
|| (!answer.equals("wei")) && !answer.equals("")) {
return "error";
} else {
return "input";
}
}
}
一共就7个文件，部署到服务器，运行就可以了
注意，比较容易出错的地方是配置XML数据校验文件，旧的版本的头部是这样写的：
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE validators PUBLIC
"-//OpenSymphony Group//XWork Validator 1.0.2//EN"
"http://www.opensymphony.com/xwork/xwork-validator-1.0.2.dtd">
因为struts2被apache收购了，所以这样写的话，会提示找不到问dtd文件，因此，有两种方法解决
第一种：
在自己电脑的磁盘下面存放xwork-validator-1.0.2.dtd文件，然后把http://www.opensymphony.com/xwork/用你xwork-validator-1.0.2.dtd所在目录替换即可，但是，这种做法不利于程序的移植。
第二种：
这方法我百度了N就才找到，参考这里面的文章http://www.cnblogs.com/javawebsoa/archive/2013/07/18/3199148.html
头部文件这样写就对了：
<!DOCTYPE validators PUBLIC
"-//Apache Struts//XWork Validator 1.0.2//EN"
"http://struts.apache.org/dtds/xwork-validator-1.0.2.dtd">
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原文地址：http://www.cnblogs.com/listentothecloud20150215/p/4303437.html
