struts的validate方法验证
输入校验是所有WEB应用必须处理的问题，输入校验分为客户端校验和服务器端校验。客户端校验主要通过JavaScript代码来完成，服务器端校验通常在应用中编程实现。
本文是基于服务器端的方法校验，利用validate框架来实现的。使用validate框架可以无需在ActionForm的子类中覆盖validate方法就可以很方便的验证客户端的提交数据。由于validate框架内置了很多预定义的验证机制，如验证Email是否合法等。所以在一般情况下，只需要配置XML文件就可以满足我们的验证需求。使用validate框架，比直接使用validate方法验证给我们带来的好处：
1.更容易维护。验证信息在一个配置文件中，所有更加利于今后维护这些验证信息。
2.标准化。如用户名和密码都要求由字母和数字组成。如果将这些验证都写在validate方法中，对这些验证进行标准化非常困难。而在validate框架中的验证机制都是预先定义的，一次，对validate框架来说是件非常容易的事。
3.避免重造轮子。减少代码的数量
下面介绍下详细的配置工作。
首先，安装validate的插件。在struts-config.xml中，添加如下的代码：
<plug-in className="org.apache.struts.validator.ValidatorPlugIn"> <set-property property="pathnames" value="/WEB-INF/validator-rules.xml,/WEB-INF/validator.xml" /> </plug-in>
<?xml version="1.0" encoding="GBK"?><!DOCTYPE form-validation PUBLIC "-//Apache Software Foundation//DTD Commons Validator Rules Configuration 1.1.3//EN" "http://jakarta.apache.org/commons/dtds/validator_1_1_3.dtd"><form-validation><formset><form name="firstValidatorForm"><field property="name" depends="required,maxlength,minlength,mask"><msg name="required" key="error.name.blank"/><msg name="minlength" key="error.name.minLength"/><msg name="maxlength" key="error.name.maxLength"/><msg name="mask" key="error.name.alphanum"/><arg name="minlength" key="${var:minlength}" position="0" resource="false"/><arg name="maxlength" key="${var:maxlength}" position="0" resource="false"/><var><var-name>minlength</var-name><var-value>5</var-value></var><var><var-name>maxlength</var-name><var-value>10</var-value></var><var><var-name>mask</var-name><var-value>^[a-zA-Z0-9]*$</var-value></var></field><field property="age" depends="required,integer,intRange"><msg name="required" key="error.age.blank"/><msg name="integer" key="error.age.integer"/><msg name="intRange" key="error.age.intRange"/><arg name="intRange" key="${var:min}" position="0" resource="false"/><arg name="intRange" key="${var:max}" position="1" resource="false"/><var><var-name>min</var-name><var-value>18</var-value></var><var><var-name>max</var-name><var-value>60</var-value></var></field><field property="email" depends="required,email"><msg name="required" key="error.email.blank"/><msg name="email" key="error.email.invalid"/></field></form></formset></form-validation> package actionform;import org.apache.struts.validator.ValidatorForm;public class FirstValidatorForm extends ValidatorForm { private String name; public String getName() {return name;}public void setName(String name) {this.name = name;}public String getAge() {return age;}public void setAge(String age) {this.age = age;}public String getEmail() {return email;}public void setEmail(String email) {this.email = email;}private String age; private String email;}package action;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.apache.struts.action.Action;import org.apache.struts.action.ActionForm;import org.apache.struts.action.ActionForward;import org.apache.struts.action.ActionMapping;public class ValidatorAction extends Action {public ActionForward execute(ActionMapping mapping, ActionForm form,HttpServletRequest request, HttpServletResponse response)throws Exception {response.setCharacterEncoding("GBK");try{response.getWriter().println("验证成功!");}catch(Exception e){}return null;}}<?xml version="1.0" encoding="GBK"?><!DOCTYPE struts-config PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 1.2//EN" "http://struts.apache.org/dtds/struts-config_1_2.dtd"><struts-config><data-sources /><form-beans><form-bean name="firstValidatorForm" type="actionform.FirstValidatorForm"/></form-beans><global-exceptions /><global-forwards /> <action-mappings > <action attribute="firstValidatorForm" name="firstValidatorForm" path="/firstValidator" scope="request" validate="true" type="action.ValidatorAction" input="/firstValidator.jsp"> </action></action-mappings><message-resources parameter="com.yourcompany.struts.ApplicationResources" /><plug-in className="org.apache.struts.validator.ValidatorPlugIn"> <set-property property="pathnames" value="/WEB-INF/validator-rules.xml,/WEB-INF/validator.xml" /> </plug-in> </struts-config>
<%@ page language="java" contentType="text/html; charset=GBK" pageEncoding="GBK"%><%@ taglib uri="http://struts.apache.org/tags-html" prefix="html"%><!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=GBK"><title>Insert title here</title></head><body><html:form action="firstValidator">姓名：<html:text property="name"/> <font color="red"><html:errors property="name"/></font><p>年龄：<html:text property="age"/> <font color="red"><html:errors property="age"/></font><p>EMail：<html:text property="email"/> <font color="red"><html:errors property="email"/></font><p><html:submit value="提交"/> </html:form></body></html>