如何进行声明式验证之字段验证？
使用一个声明式验证程序需要 3 个步骤:
1. 确定哪些 Action 字段需要验证
2. 编写一个验证程序配置文件. 它的文件名必须是以下两种格式之一:
若一个 Action 类的多个 action 使用同样的验证规则: ActionClassName-validation.xml
若一个 Action 类的多个 action 使用不同的验证规则: ActionClass-alias-validation.xml, 例如 UserAction-User_create-validation.xml （想了解这个条如何使用，请点击 
）
3. 确定验证失败时的响应页面: 在 struts.xml 文件中定义一个 <result name=“input”> 的元素.
如何进行声明式验证之字段验证？
1 搭建环境：
eclipase：Luna Release (4.4.0)
sturts2：2.3.28 下载地址：http://download.csdn.net/detail/chuck_kui/9513090
项目结构：
~~~~~~~~~~~~~~~~~~~华华 ......，严肃点 。嗯 ，好的，这是分割线~~~~~~~~~~
类
Person.java
<span style="font-size:14px;">package com.baidu.domain;
public class Person {
private Integer age;
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
@Override
public String toString() {
return "Person [age=" + age + "]";
}
}</span><span style="font-weight: bold; font-size: 18px;">
</span>
Action ：TestAgeValidation.java
<span style="font-size:14px;">package com.baidu.ActionValidation;
import com.baidu.domain.Person;
import com.opensymphony.xwork2.ActionSupport;
import com.opensymphony.xwork2.ModelDriven;
import com.opensymphony.xwork2.Preparable;
public class TestAgeValidation extends ActionSupport implements
ModelDriven<Person>, Preparable {
private static final long serialVersionUID = 1L;
@Override
public String execute() throws Exception {
return super.execute();
}
private Person person;
@Override
public Person getModel() {
person = new Person();
return person;
}
@Override
public void prepare() throws Exception {
System.out.println("进来了吗？");
}
}</span>
验证器：TestAgeValidation-validation.xml
<span style="font-size:14px;"><!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="age">
<field-validator type="int">
<param name="min">20</param>
<param name="max">50</param>
<message>Age needs to be 22222 between ${min} and ${max}</message>
</field-validator>
</field>
</validators></span>
配置：
struts.xml
<span style="font-size:14px;"><?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"> <struts> <!-- 配置全局的国际化资源文件 --> <constant name="struts.custom.i18n.resources" value="nihao"></constant> <package name="default" namespace="/" extends="struts-default"> <!-- 这个就是起烂笔头的作用 --> <interceptors> <interceptor-stack name="baiduStack"> <interceptor-ref name="paramsPrepareParamsStack"> <param name="prepare.alwaysInvokePrepare">false</param> </interceptor-ref> </interceptor-stack> </interceptors> <default-interceptor-ref name="baiduStack"/> <action name="testAge" class="com.baidu.ActionValidation.TestAgeValidation"> <result>/success.jsp</result> <result name="input">/validation.jsp</result> </action> </package> </struts></span>
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
<filter>
<filter-name>struts2</filter-name>
<filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>struts2</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>
页面：validation.jsp
<span style="font-size:14px;"><%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags" %>
<!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>Insert title here</title>
</head>
<body>
<center>
<br><br>
<s:form action="testAge" >
<s:textfield name="age" label="Age"></s:textfield>
<s:submit></s:submit>
</s:form>
</center>
</body>
</html></span>
success.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags" %>
<!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>Insert title here</title>
</head>
<body>
Age:<s:property value="age" />
<h3>恭喜你有为青年！</h3>
</body>
</html>
55 大于50 报提示与页面
等于20 验证通过，
验证器好用！