在專案 HeadFirstStruts2chapter07 下，在src下匯入validator.xml檔案，
新建一個com.cruise.validators包，新建SensitiveWorkds類，繼承，寫驗證方法，
package com.cruise.validators;

import com.opensymphony.xwork2.validator.ValidationException;
import com.opensymphony.xwork2.validator.validators.FieldValidatorSupport;

public class

 SensitiveWordValidators extends FieldValidatorSupport{

    @Override
    public void validate(Object arg0) throws ValidationException {
       String fieldName2 = this.getFieldName();//獲取欄位名稱
       String value = this.getFieldValue(fieldName2, arg0).toString();//獲取欄位的值
       if(!check(value)){
           this.addFieldError(fieldName2, arg0);
       }
    }
    
    public boolean check(String value){
       String[] sensitivewords = new String[]{"操","你媽"};
       for(String i :sensitivewords){
           if(value.indexOf(i)>-1){
              return false;
           }
       }
       return true;
    }
}
2在validator.xml中新增SensitiveWorkds類的引用，
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE validators PUBLIC
        "-//Apache Struts//XWork Validator Config 1.0//EN"
        "http://struts.apache.org/dtds/xwork-validator-config-1.0.dtd">
<validators>
    <validator name="required"class="com.opensymphony.xwork2.validator.validators.RequiredFieldValidator"/>
    <validator name="requiredstring"class="com.opensymphony.xwork2.validator.validators.RequiredStringValidator"/>
    <validator name="int"class="com.opensymphony.xwork2.validator.validators.IntRangeFieldValidator"/>
    <validator name="double"class="com.opensymphony.xwork2.validator.validators.DoubleRangeFieldValidator"/>
    <validator name="date"class="com.opensymphony.xwork2.validator.validators.DateRangeFieldValidator"/>
    <validator name="expression"class="com.opensymphony.xwork2.validator.validators.ExpressionValidator"/>
    <validator name="fieldexpression"class="com.opensymphony.xwork2.validator.validators.FieldExpressionValidator"/>
    <validator name="email"class="com.opensymphony.xwork2.validator.validators.EmailValidator"/>
    <validator name="url"class="com.opensymphony.xwork2.validator.validators.URLValidator"/>
    <validator name="visitor"class="com.opensymphony.xwork2.validator.validators.VisitorFieldValidator"/>
    <validator name="conversion"class="com.opensymphony.xwork2.validator.validators.ConversionErrorFieldValidator"/>
    <validator name="stringlength"class="com.opensymphony.xwork2.validator.validators.StringLengthFieldValidator"/>
    <validator name="regex"class="com.opensymphony.xwork2.validator.validators.RegexFieldValidator"/>
    <validator name="conditionalvisitor"class="com.opensymphony.xwork2.validator.validators.ConditionalVisitorFieldValidator"/>
<validator name="sensitive" class="com.cruise.validators.SensitiveWordValidators"/>
</validators>
3新建ValidationAction類，name屬性，get() set()
package com.cruise.action;

import com.opensymphony.xwork2.ActionSupport;

public class ValidationAction extends ActionSupport{
    
    private String name ;

    public String getName() {
       return name;
    }

    public void setName(String name) {
       this.name = name;
    }
    @Override
    public String execute() throws Exception {
       System.out.println("姓名："+name);
       return SUCCESS;
    }
}
4新建ValidationAction-validation.xml檔案，放在src下，（檔名寫法：相同Action名-validation.xml）
sensitive的名字要與validation.xml中自己定義的驗證器的name屬性的值一致
<?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>請輸入名字！！！</message>
       </field-validator>
       <field-validator type="sensitive">
           <message>含有敏感詞彙</message>
       </field-validator>
    </field>
</validators>
5配置struts.xml檔案中的validationAction，
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
    "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
    "http://struts.apache.org/dtds/struts-2.0.dtd">

<struts>
    <package name="manager" extends="struts-default">
       <action name="validationAction" class="com.cruise.action.ValidationAction">
           <result name="input">/validation.jsp</result>
           <result name="success">/success.jsp</result>
       </action>
    </package>
</struts>
6新建validation.jsp 檔案
<%@ 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>
<s:actionerror/>
註冊
<s:form action="/validationAction" method="post">
    <s:textfield name="name" label="名字"></s:textfield>
    <s:submit value="提交"></s:submit>
</s:form>
</body>
</html>
測試
http://localhost:8080/HeadFirstStruts2chapter07/validation.jsp