Spring MVC - Hibernate Validator Example

The following example shows how to use Error Handling and Validators in forms using the Spring Web MVC framework. To begin with, let us have a working Eclipse IDE in place and adhere to the following steps to develop a Dynamic Form based Web Application using the Spring Web Framework.

Student.java

package com.howcodex;

import org.hibernate.validator.constraints.NotEmpty;
import org.hibernate.validator.constraints.Range;

public class Student {

   @Range(min = 1, max = 150) 
   private Integer age;
   @NotEmpty
   private String name;
   private Integer id;

   public void setAge(Integer age) {
      this.age = age;
   }
   public Integer getAge() {
      return age;
   }

   public void setName(String name) {
      this.name = name;
   }
   public String getName() {
      return name;
   }

   public void setId(Integer id) {
      this.id = id;
   }
   public Integer getId() {
      return id;
   }
}

StudentController.java

package com.howcodex;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.validation.BindingResult;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.servlet.ModelAndView;

@Controller
public class StudentController {

   @RequestMapping(value = "/addStudent", method = RequestMethod.GET)
   public ModelAndView student() {
      return new ModelAndView("addStudent", "command", new Student());
   }

   @ModelAttribute("student")
   public Student createStudentModel() {	
      return new Student();
   }

   @RequestMapping(value = "/addStudent", method = RequestMethod.POST)
   public String addStudent(@ModelAttribute("student") @Validated Student student, 
      BindingResult bindingResult, Model model) {
      if (bindingResult.hasErrors()) {
         return "addStudent";
      }
      model.addAttribute("name", student.getName());
      model.addAttribute("age", student.getAge());
      model.addAttribute("id", student.getId());

      return "result";
   }
}

messages.properties

NotEmpty.student.name = Name is required!
Range.student.age = Age value must be between 1 and 150!

Here, the key is <Annotation>.<object-name>.<attribute>. Value is the message to be displayed.

TestWeb-servlet.xml

<beans xmlns = "http://www.springframework.org/schema/beans"
   xmlns:context = "http://www.springframework.org/schema/context"
   xmlns:mvc = "http://www.springframework.org/schema/mvc"
   xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation = "
   http://www.springframework.org/schema/beans     
   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
   http://www.springframework.org/schema/context 
   http://www.springframework.org/schema/context/spring-context-3.0.xsd
   http://www.springframework.org/schema/mvc
   http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">

   <context:component-scan base-package = "com.howcodex" />
   <mvc:annotation-driven />
   <bean class = "org.springframework.context.support.ResourceBundleMessageSource"
      id = "messageSource">
      <property name = "basename" value = "messages" />
   </bean>
   <bean class = "org.springframework.web.servlet.view.InternalResourceViewResolver">
      <property name = "prefix" value = "/WEB-INF/jsp/" />
      <property name = "suffix" value = ".jsp" />      
   </bean>
</beans>

Here, for the first service method student(), we have passed a blank Studentobject> in the ModelAndView object with name "command", because the spring framework expects an object with name "command", if you are using <form:form> tags in your JSP file. So, when the student() method is called, it returns addStudent.jsp view.

The second service method addStudent() will be called against a POST method on the HelloWeb/addStudent URL. You will prepare your model object based on the submitted information. Finally, a "result" view will be returned from the service method, which will result in rendering the result.jsp. In case there are errors generated using validator then same view "addStudent" is returned, Spring automatically injects error messages from BindingResult in view.

addStudent.jsp

<%@taglib uri = "http://www.springframework.org/tags/form" prefix = "form"%>
<html>
   <head>
      <title>Spring MVC Form Handling</title>
   </head>
   <style>
      .error {
         color: #ff0000;
      }

      .errorblock {
         color: #000;
         background-color: #ffEEEE;
         border: 3px solid #ff0000;
         padding: 8px;
         margin: 16px;
      }
   </style>
   <body>

      <h2>Student Information</h2>
      <form:form method = "POST" action = "/TestWeb/addStudent" commandName = "student">
      <form:errors path = "*" cssClass = "errorblock" element = "div" />
         <table>
            <tr>
               <td><form:label path = "name">Name</form:label></td>
               <td><form:input path = "name" /></td>
               <td><form:errors path = "name" cssClass = "error" /></td>
            </tr>
            <tr>
               <td><form:label path = "age">Age</form:label></td>
               <td><form:input path = "age" /></td>
               <td><form:errors path = "age" cssClass = "error" /></td>
            </tr>
            <tr>
               <td><form:label path = "id">id</form:label></td>
               <td><form:input path = "id" /></td>
               </tr>
            <tr>
               <td colspan = "2">
               <input type = "submit" value = "Submit"/>
               </td>
            </tr>
         </table>  
      </form:form>
   </body>
</html>

Here, we are using the <form:errors /> tag with path="*" to render error messages. For example −

<form:errors path = "*" cssClass = "errorblock" element = "div" />

It will render error messages for all input validations. We are using <form:errors /> tag with path = "name" to render error message for the name field.

For example −

<form:errors path = "name" cssClass = "error" />
<form:errors path = "age" cssClass = "error" />

It will render error messages for name and age field validations.

result.jsp

<%@taglib uri = "http://www.springframework.org/tags/form" prefix = "form"%>
<html>
   <head>
      <title>Spring MVC Form Handling</title>
   </head>
   <body>

      <h2>Submitted Student Information</h2>
      <table>
         <tr>
            <td>Name</td>
            <td>${name}</td>
         </tr>
         <tr>
            <td>Age</td>
            <td>${age}</td>
         </tr>
         <tr>
            <td>ID</td>
            <td>${id}</td>
         </tr>
      </table>  
   </body>
</html>

Once you are done with creating source and configuration files, export your application. Right click on your application, use Export → WAR File option and save the HelloWeb.war file in Tomcat's webapps folder.

Now, start the Tomcat server and make sure you are able to access other webpages from the webapps folder using a standard browser. Try a URL − http://localhost:8080/TestWeb/addStudent and we will see the following screen, if you have entered invalid values.