Spring MVC Form Regular Expression Validation

Last updated on May 17th, 2024

In this example, we can validate user input of the particular regular expressions using this @Pattern annotation and pass some required regular expression values to the regexp attribute.  

Development Process:
   1. Keep Eclipse IDE ready
   2. Project Structure
   3. Add the jar file
   4. Configure Spring DispacherServlet
   5. Add configuration to the file
   6. Create Bean Class
   7. Create a View Page
   8. Create Controller Class
   9. Run the App

1. Keep Eclipse IDE ready
2. Project Structure

3. Add the jar file

4. Configure Spring DispacherServlet 
web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4.xsd" id="WebApp_ID" version="4.0">

<display-name>spring-mvc-regular-expression-validation-demo</display-name>
<absolute-ordering />

<!-- Spring MVC Configs -->
<!--  Configure Spring MVC Dispatcher Servlet -->
<servlet>
<servlet-name>dispatcher</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/dispatcher-servlet.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<!-- Set up URL mapping for Spring MVC Dispatcher Servlet -->
<servlet-mapping>
<servlet-name>dispatcher</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>

→ The file is created in the WEB-INF directory in the application(spring_mvc_regular_expression_validation_demo)

5. Add configuration to file
dispatcher-servlet.xml:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd">


<!-- Add support for component scanning -->
<context:component-scan base-package="com.poc" />

<!-- Add support for conversion, formatting and validation support -->
<mvc:annotation-driven/>

<!-- Define Spring MVC view resolver -->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/view/" />
<property name="suffix" value=".jsp" />
</bean>
</beans>

6. Create Bean Class
User.java:

package com.poc.controller.bean;

import javax.validation.constraints.Pattern;

public class User {

private String firstName;
private String lastName;
@Pattern(regexp = "^[0-9A-Z@#$&%*]+$", message = "This accepts 1 range or more than 1 range")
private String password;

public User() {

}

public String getFirstName() {

return firstName;

}

public void setFirstName(String firstName) {

this.firstName = firstName;

}


public String getLastName() {

return lastName;

}


public void setLastName(String lastName) {

this.lastName = lastName;

}


public String getPassword() {

return password;

}

public void setPassword(String password) {

this.password = password;

   }
}

→ Add validation rule in this bean we are using @Pattern(regexp = “^[1-9a-z]+$”, message = “This accepts 1 range or more than 1 range”) is validating field matches with this expression if failed then the message is shown.

7. Create a View Page
home.jsp:

<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>

<!DOCTYPE html>
<html>
<head>
<body>
<a href="http://localhost:8080/spring_mvc_regular_expression_validation_demo/user/showForm">Click For User Form</a>
</body>
</html>

user-form.jsp:

<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>

<!DOCTYPE html>
<html>
<head>
<title>User Registration Form</title>
<style>
.error {color:red}
</style>
</head>
<body>
<form:form action="processForm" modelAttribute="user">
First name: <form:input path="firstName" />
<br>
<br>
Last name: <form:input path="lastName" />
<br>
<br>
Password (*): <form:password path="password" />
<form:errors path="password" cssClass="error" />
<br>
<br>
<input type="submit" value="Submit" />
</form:form>
</body>
</html>

→ <form:errors path=”password” cssClass=”error” />is displaying a message when the password field fails to validate the specific pattern of the rule.
user-detail.jsp:

<!DOCTYPE html>
<html>
<head>
<title>User Detail</title>
</head>
<body>User Name: ${user.firstName} ${user.lastName} <br>
Password:${user.password}
</body>
</html>

8. Create Controller Class
HomeController.java:

package com.poc.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

@Controller
public class HomeController {

@RequestMapping("/")
public String showPage() {

return "home";
   }
 }

UserController.java:

package com.poc.controller;

import javax.validation.Valid;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import com.poc.controller.bean.User;

@Controller
@RequestMapping("/user")
public class UserController{


@RequestMapping("/showForm")
public String showForm(Model theModel) {

// create a User object
User user=new User();

theModel.addAttribute("user",user);

return "user-form";

}


@RequestMapping("/processForm")
public String processForm(@ModelAttribute("user") @Valid User user,BindingResult bindingResult){

if (bindingResult.hasErrors()) {
return "user-form";
}
else {
return "user-detail";
          }
        }
     }

→ @Valid is performing validation rules on the User object.
→ The Outcome of the validation is placed on the BindingResult Interface.

9. Run the App

spring_mvc_form_regular_expression_validation
spring_mvc_form_regular_expression_validation
spring_mvc_form_regular_expression_validation

Conclusion:
This example explains How to use regular expression validation. How to put in the validation rules to Bean class? How to use <form:errors/> tag?

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