validator框架总结

validator框架总结

validator框架能够克服在ActionForm Bean中以编程方式进行数据验证的局限，它允许Struts应用灵活的配置验证规则，无需编程。

Validator框架主要依赖两个JAR文件：jakarta-oro.jar和commons-validator,.jar

Validator框架采用两个基于XML的配置文件来配置验证规则。这两个文件为validator-rules.xml和validation.xml。

 

1.     struts调用validator框架的过程：

struts-config.xml 文件中配置struts的validator插件

<plug-in className="org.apache.struts.validator.ValidatorPlugIn">

<set-property property="pathnames"

value="/WEB-INF/validator-rules.xml,                                      /WEB-INF/validation.xml"/>

 </plug-in>

容器启动时，ActionServlet调用插件ValidatorPlugIn的init方法。

init方法首先调用initResources方法，此方法通过读取参数pathnames取得值value并分析这两个xml文件，返回validatorResources对象。然后将这个对象保存进application作用域。

 

public void init(ActionServlet servlet, ModuleConfig config)

        throws ServletException {

        ......

        try {

            this.initResources();

 

            servlet.getServletContext().setAttribute(VALIDATOR_KEY

                + config.getPrefix(), resources);

           .....

 

          

        } catch (Exception e) {

           ......

        }

当服务器接受请求，它会调用ValidatorForm类的validate方法进行表单验证。

ValidatorForm的validate方法中调用Resources.InitValidator方法初始化Validator对象，并调用setParamter方法为校验方法传递参数，最后调用validator.validate()方法执行校验。

public ActionErrors validate(ActionMapping mapping,

        HttpServletRequest request) {

       ......

        String validationKey = getValidationKey(mapping, request);

        //返回Validator对象

        Validator validator =

            Resources.initValidator(validationKey, this, application, request,                errors, page);

 

        try {

            validatorResults = validator.validate();

        } catch (ValidatorException e) {

          ......

        }

 

        return errors;

}

public static Validator initValidator(......){

......

ValidatorResources resources =

            Resources.getValidatorResources(application, request);

//通过rources和formbean的名字得到Validator对象。

               Validator validator = new Validator(resources, key);

validator.setParameter(SERVLET_CONTEXT_PARAM, application);

        validator.setParameter(HTTP_SERVLET_REQUEST_PARAM, request);

        validator.setParameter(Validator.LOCALE_PARAM, locale);

        validator.setParameter(ACTION_MESSAGES_PARAM, errors);

        validator.setParameter(Validator.BEAN_PARAM, bean);

......

}

public String getValidationKey(ActionMapping mapping,

        HttpServletRequest request) {

        return mapping.getAttribute();

}

 

这里：getValidationKey返回struts-config.xml中action元素的attribute属性的值，它对应Form的name属性的值，表示要对哪个formbean进行校验。

<form name="regUserForm">

        <field property="name" depends="required">

        。。。

        </field>

 

        

validator的validate()方法调用Form，Field对象（根据配置文件实例化对象）的validate方法分别进行校验，返回一个ValidatorResults对象。ValidatorResults对象包含所有校验的结果。

 

 

2.如何扩展自己的校验器。

package com.wll.util;

 

import java.io.Serializable;

 

import javax.servlet.http.HttpServletRequest;

 

import org.apache.commons.validator.Field;

import org.apache.commons.validator.GenericValidator;

import org.apache.commons.validator.Validator;

import org.apache.commons.validator.ValidatorAction;

import org.apache.commons.validator.util.ValidatorUtils;

import org.apache.struts.action.ActionMessages;

import org.apache.struts.validator.Resources;

 

public class MyFieldChecks implements Serializable {

 

     

        public static boolean validateIdCard(Object bean,

                ValidatorAction va, Field field,

                ActionMessages errors,

                Validator validator,

                HttpServletRequest request) {

 

        String value = null;

 

           value = ValidatorUtils.getValueAsString(bean, field.getProperty());

           if (value.length()!=15 || !isDigits(value)){

              errors.add(field.getKey(), Resources.getActionMessage(validator, request, va, field));         

              return false;

           }

              return true;

       }

 

       private static boolean isDigits(String value) {

           // TODO Auto-generated method stub

           int len = value.length();

           for(int i=0;i<len;i++)

           {  

              if(!Character.isDigit(value.charAt(i)))

              return false;

           }

           return true;

       }

     

 

}

 

配置如下：

validation.xml

<form name="creditCard">

        <field property="card" depends="cardRequired">

        <arg key="prompt.card"/>

        </field>

</form>

validator-rules.xml

<validator name="cardRequired"

            classname=" com.wll.util.MyFieldChecks"

               method=" validateIdCard "

         methodParams="java.lang.Object,

                       org.apache.commons.validator.ValidatorAction,

                       org.apache.commons.validator.Field,

                       org.apache.struts.action.ActionMessages,

                       org.apache.commons.validator.Validator,

                       javax.servlet.http.HttpServletRequest"

                  msg="errors.card"/>

资源文件中

errors.card={0} is not valid.

prompt.card=creditcard