Spring MVC Form Validation Example

Validation and Submission of a form is an important aspect of a web application. In this tutorial, we will show how to validate the form fields of a simple login form using the Spring MVC framework.

1. Spring MVC Form Validation – Introduction

1.1 Spring Framework

• Spring is an open-source framework created to address the complexity of an enterprise application development
• One of the chief advantages of the Spring framework is its layered architecture, which allows a developer to be selective about which of its components they can use while providing a cohesive framework for J2EE application development
• Spring framework provides support and integration to various technologies for e.g.:
  • Support for Transaction Management
  • Support for interaction with the different databases
  • Integration with the Object Relationship frameworks for e.g. Hibernate, iBatis etc
  • Support for Dependency Injection which means all the required dependencies will be resolved with the help of containers
  • Support for REST style web-services

1.2 Spring Mvc Framework

Model-View-Controller (Mvc) is a well-known design pattern for designing the GUI based applications. It mainly decouples the business logic from UI by separating the roles of Model, View, and Controller in an application. This pattern divides the application into three components to separate the internal representation of the information from the way it is being presented to the user. The three components are:

• Model (M): Model’s responsibility is to manage the application’s data, business logic, and the business rules. It is a POJO class which encapsulates the application data given by the controller
• View (V): A view is an output representation of the information, such as displaying information or reports to the user either as a text-form or as charts. Views are usually the JSP templates written with Java Standard Tag Library (JSTL)
• Controller (C): Controller’s responsibility is to invoke the Models to perform the business logic and then update the view based on the model’s output. In the spring framework, the controller part is played by the Dispatcher Servlet

Now, open up the Eclipse IDE and let’s see how to implement the form validation functionality in the spring mvc framework!

2. Spring MVC Form Validation Example

Here is a step-by-step guide for implementing this tutorial in the spring mvc framework.

2.1 Tools Used

We are using Eclipse Kepler SR2, JDK 8 and Maven. Having said that, we have tested the code against JDK 1.7 and it works well.

2.2 Project Structure

Firstly, let’s review the final project structure, in case you are confused about where you should create the corresponding files or folder later!

2.3 Project Creation

This section will demonstrate how to create a Java-based Maven project with Eclipse. In Eclipse IDE, go to File -> New -> Maven Project.

In the New Maven Project window, it will ask you to select project location. By default, ‘Use default workspace location’ will be selected. Just click on next button to proceed.

Select the Maven Web App archetype from the list of options and click next.

It will ask you to ‘Enter the group and the artifact id for the project’. We will input the details as shown in the below image. The version number will be by default: 0.0.1-SNAPSHOT.

Click on Finish and the creation of a maven project is completed. If you observe, it has downloaded the maven dependencies and a pom.xml file will be created. It will have the following code:

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.spring.mvc</groupId>
	<artifactId>SpringMvcFormValidation</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>war</packaging>
</project>

We can start adding the dependencies that developers want like Servlet API, Spring Mvc etc. Let’s start building the application!

3. Application Building

Below are the steps involved in developing this application.

3.1 Maven Dependencies

Here, we specify the dependencies for the spring mvc framework and the bean validation api (a.k.a hibernate-validator-&ltversion_number>.Final.jar). The rest dependencies such as Spring Beans, Spring Core, Validation API etc. will be automatically resolved by Maven. The updated file will have the following code:

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<groupId>com.spring.mvc</groupId>
	<artifactId>SpringMvcFormValidation</artifactId>
	<packaging>war</packaging>
	<version>0.0.1-SNAPSHOT</version>
	<name>SpringMvcFormValidation Maven Webapp</name>
	<url>http://maven.apache.org</url>
	<dependencies>
		<!-- Servlet API Dependency -->
		<dependency>
			<groupId>javax.servlet</groupId>
			<artifactId>servlet-api</artifactId>
			<version>3.0-alpha-1</version>
		</dependency>
		<!-- Spring Framework Dependencies -->
		<dependency>
			<groupId>org.springframework</groupId>
			<artifactId>spring-webmvc</artifactId>
			<version>5.0.6.RELEASE</version>
		</dependency>
		<!-- jar is used for showing the server side validations in the spring 
			framework -->
		<dependency>
			<groupId>org.hibernate.validator</groupId>
			<artifactId>hibernate-validator</artifactId>
			<version>6.0.10.Final</version>
		</dependency>
	</dependencies>
	<build>
		<finalName>SpringMvcFormValidation</finalName>
	</build>
</project>

3.2 Configuration Files

Let’s write all the configuration files involved in this application.

3.2.1 Web Deployment Descriptor

The web.xml file declares one servlet (i.e. Dispatcher Servlet) to receive all kind of the requests. Dispatcher servlet here acts as a front controller. Add the following code to it:

web.xml

<!DOCTYPE web-app PUBLIC
 "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
 "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
	<display-name>SpringMvcFormValidationExample</display-name>

	<servlet>
		<servlet-name>springmvcformvalidationdispatcher</servlet-name>
		<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
	</servlet>

	<servlet-mapping>
		<servlet-name>springmvcformvalidationdispatcher</servlet-name>
		<url-pattern>/</url-pattern>
	</servlet-mapping>
</web-app>

3.2.2 Spring Configuration File

To configure the spring framework, developers need to implement a bean configuration file i.e. springmvcformvalidationdispatcher-servlet.xml which provide an interface between the basic Java class and the outside world. Add the following code to it:

springmvcformvalidationdispatcher-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">

	<mvc:annotation-driven />

	<context:component-scan base-package="com.spring.mvc.demo" />
	<context:component-scan base-package="com.spring.mvc.demo.pojo" />

	<context:annotation-config />

	<!-- For reading the properties files -->
	<bean id="messageSource"
		class="org.springframework.context.support.ReloadableResourceBundleMessageSource">
		<property name="basename" value="/WEB-INF/message" />
	</bean>

	<!-- For resolving the view name and invoking the particular view page for 
		the user -->
	<bean id="viewResolver"
		class="org.springframework.web.servlet.view.InternalResourceViewResolver">
		<property name="prefix" value="/WEB-INF/views/" />
		<property name="suffix" value=".jsp" />
	</bean>
</beans>

Do note:

• This file is loaded by the spring’s Dispatcher Servlet which receives all the requests coming into the application and dispatches them to the controller for processing
• This file has the ReloadableResourceBundleMessageSource bean declaration that tells the spring framework to localize the validation error messages for the login form fields. Here,
  • The basename property is a mandatory attribute that provides the location of the resource bundles
• This file has the InternalResourceViewResolver bean declaration that tells the framework how to find the physical JSP files according to the logical view names returned by the controllers, by attaching the prefix and the suffix to a view name

3.3 Message Resource File

We will create a properties file which will contain the validation error message for the login form fields. Create the message.properties file in the SpringMvcFormValidation/src/main/webapp/WEB-INF folder and add the following code to it:

message.properties

## userform.email ##
NotEmpty.userform.email=Please enter your e-mail.
Email.userform.email=Your e-mail is incorrect.

## userform.password ##
Size.userform.password=Your password must between 6 and 10 characters.

3.4 Java Class Creation

Let’s write the Java classes involved in this application.

3.4.1 Model Class

Let’s create a simple model class. In this class, the member variables are annotated with the validation constraint annotations such as: @NotEmpty, @Email, @Size. Do note, the error messages are specified in the properties file for demonstrating the localization of the validation error messages. Add the following code to it:

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User.java

package com.spring.mvc.demo.pojo;

import javax.validation.constraints.Email;
import javax.validation.constraints.NotEmpty;
import javax.validation.constraints.Size;

import org.springframework.stereotype.Component;

@Component
public class User {

	@NotEmpty
	@Email
	private String email;
	
	@Size(min=6, max=10, message="Size.userform.password")
	private String password;

	public User() { }

	public String getEmail() {
		return email;
	}
	public void setEmail(String email) {
		this.email = email;
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
}

3.4.2 Controller Class

Let’s create a simple class where the @Controller annotation specifies this class as a spring controller and is responsible for handling the incoming requests. In here, the model object is annotated with the @Valid annotation that binds the model object properties with the inputs from the JSP form that uses the spring’s form tags. Any constraints violations will be exported as errors in the BindingResult object. Add the following code to it:

FormCtrl.java

package com.spring.mvc.demo;

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 org.springframework.web.bind.annotation.RequestMethod;

import com.spring.mvc.demo.pojo.User;

@Controller
public class FormCtrl {

	@RequestMapping(value= "/init", method= RequestMethod.GET)
	public String initView(Model model) {
		model.addAttribute("userform", new User());
		return "loginForm";
	}

	@RequestMapping(value= "/login", method= RequestMethod.POST)
	public String doLogin(@Valid @ModelAttribute("userform") User user, BindingResult result) {
		if (result.hasErrors()) {
			return "loginForm";
		}

		return "success";
	}
}

3.5 JSP View

Spring Mvc supports many types of views for different presentation technologies. These include – JSP, HTML, XML etc. So let us write a simple result view in SpringMvcFormValidation/src/main/webapp/WEB-INF/views folder.

3.5.1 Input Form Page

This is the login form page of the tutorial which takes the user input and displays the appropriate error messages in case of the validation errors. Add the following code to it:

loginForm.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
<%@ page isELIgnored="false" %>
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
	<head>
		<title>Login</title>
	    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
	    <link rel="stylesheet" href="https://examples.javacodegeeks.com/wp-content/litespeed/localres/aHR0cHM6Ly9tYXhjZG4uYm9vdHN0cmFwY2RuLmNvbS8=bootstrap/4.1.3/css/bootstrap.min.css">
	    <style type="text/css">
	        .errormsg {
	            color: red;
	        }
	    </style>
	</head>
	<body>
		<div class="container">
		    <h2 align="center" class="text-primary">Spring MVC Form Validation Example</h2>
		    <hr />
		    <div> </div>

	    	<form:form action="/SpringMvcFormValidation/login" method="POST" modelAttribute="userform">
	    		 <div class="form-group">
	     			<label>Email:</label><form:input path="email" size="30" cssClass="form-control" placeholder="Enter email" />			   
				    <small><form:errors path="email" cssClass="errormsg" /></small>
				 </div>
				 <div class="form-group">
				    <label>Password:</label><form:password path="password" size="30" cssClass="form-control" placeholder="Enter password" />
				    <small><form:errors path="password" cssClass="errormsg" /></small>
				 </div>
				 <div class="form-group">
				    <button type="submit" class="btn btn-primary">Validate</button>
				 </div>
	    	</form:form>
	    </div>
	</body>
</html>

3.5.2 Output Page

The success page will be displayed in case the user enters a valid email address and password. Add the following code to it:

success.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
<%@ page isELIgnored="false" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
	<head>
		<title>Welcome</title>
	    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
	    <link rel="stylesheet" href="https://examples.javacodegeeks.com/wp-content/litespeed/localres/aHR0cHM6Ly9tYXhjZG4uYm9vdHN0cmFwY2RuLmNvbS8=bootstrap/4.1.3/css/bootstrap.min.css">	    
	</head>
	<body>
		<div class="container">
	    	<h2 align="center" class="text-primary">Spring MVC Form Validation Example</h2>
	    	<hr />
	    	<div> </div>
	    	
	        <h4 align="center">Welcome <span class="text-success">${userform.email}</span>! You're successfully logged in.</h4>
	    </div>
	</body>
</html>

4. Run the Application

As we are ready with all the changes, let us compile the project and deploy the application on the Tomcat7 server. To deploy the application on Tomat7, right-click on the project and navigate to Run as -> Run on Server.

Tomcat will deploy the application in its web-apps folder and shall start its execution to deploy the project so that we can go ahead and test it on the browser.

5. Project Demo

Open your favorite browser and hit the following URL to display the application’s login form page.

http://localhost:8082/SpringMvcFormValidation/

Server name (localhost) and port (8082) may vary as per your tomcat configuration.

Try to enter an invalid email address and a short password (e.g. 4 characters), and click the Validate button. Users will see the validation error messages in red, as shown below.

Now enter a valid email address and a valid password (between 6 and 10 characters), and click the Validate button. The login success page appears.

That’s all for this tutorial and I hope the article served you whatever you were looking for. Happy Learning and don’t forget to share!

6. Conclusion

In this section, developers learned how to implement form validation in the spring mvc framework. Developers can download the sample application as an Eclipse project in the Downloads section.

7. Download the Eclipse Project

This was an example of Spring MVC Form Validation.

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