Struts 2 regex validator

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The regex validator is used validates a string field against a regular expression.

Plain validator syntax of regex validator.

<validators> 
  <validator type="regex">
    <param name=”fieldName">fieldName</param>
    <param name="regex"> regex</param>  
    <message>message string</message>
  </validator>
</validators>

Field validator syntax of regex validator.

<validators> 
   <field name="fieldName">
 	<field-validator type="regex”>
                <param name="regex"> regex</param>  
       		<message>message string</message>
        </field-validator>
    </field>
</validators>

Struts 2 regex validator example:

login.jsp

<%@ taglib uri="/struts-tags" prefix="s"%>
<html>
	<head>
		<title>Struts 2 regex validator example</title>
	</head>
	<body>
		<h3>This is a regex validator example.</h3>
 
		<s:form action="Login">
			<s:textfield name="userName" label="UserName" />
			<s:textfield name="expression" label="Expression"/>
			<s:submit value="login" align="center"/>
		</s:form>
 
	</body>
</html>

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
	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_2_5.xsd">
 
 
 	<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>
 
	<welcome-file-list>
	  <welcome-file>login.jsp</welcome-file>
	</welcome-file-list>
 
</web-app>

struts.xml

<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">
 
<struts>
 
	<package name="user" extends="struts-default">
		<action name="Login" 
		          class="com.w3schools.action.Login">
		  <result name="success">/welcome.jsp</result>
		  <result name="input">/login.jsp</result>
		</action>
	</package>
 
</struts>

Login.java

import com.opensymphony.xwork2.ActionSupport;
 
/**
 * This class is used as an action class.
 * @author w3schools
 */
public class Login extends ActionSupport{
	//data members
	private String userName;
	private String expression;
 
	//business logic
	public String execute(){
		return SUCCESS;	
	}	
 
	//getter setters
	public String getUserName() {
		return userName;
	}
	public void setUserName(String userName) {
		this.userName = userName;
	}
 
	public String getExpression() {
		return expression;
	}
 
	public void setExpression(String expression) {
		this.expression = expression;
	}	
}

Login-validation.xml

<!DOCTYPE validators PUBLIC 
"-//OpenSymphony Group//XWork Validator 1.0.2//EN"
"http://www.opensymphony.com/xwork/xwork-validator-1.0.2.dtd">
 
<validators>
   <field name="userName">
      <field-validator type="requiredstring">
         <param name="trim">true</param>
         <message>
            Username is required.
         </message>
      </field-validator>
   </field>
 
   <field name="expression">
         <field-validator type="regex">
         <param name="expression">[A-Z,a-z,0-9]{6}</param>
         <message>
            Invalid expression, it can contain 
            only [A-Z,a-z,0-9] and should be of 6 characters.
         </message>
      </field-validator>
   </field>
</validators>

welcome.jsp

<%@ taglib uri="/struts-tags" prefix="s"%>
<html>
	<head>
		<title>Struts 2 regex validator example</title>
	</head>
	<body>
		<h3>This is a regex validator example.</h3>
 
		Hello <s:property value="userName" />
 
	</body>
</html>

Output:

struts 21 login
 
Enter UserName and Expression.
struts 21 value
 
Click on login button.
struts 21 final
 
Download this example.
 
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