Spring MVC - Error Handling Example

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

Step	Description
1	Create a project with a name HelloWeb under a package com.tutorialspoint as explained in the Spring MVC - Hello World Example chapter.
2	Create a Java classes Student, StudentController, and StudentValidator under the com.tutorialspoint package.
3	Create a view files addStudent.jsp, result.jsp under jsp sub-folder.
4	The final step is to create the content of all the source and configuration files and export the application as explained below.

Student.java

package com.tutorialspoint;

public class Student {
   private Integer age;
   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;
   }
}

StudentValidator.java

package com.tutorialspoint;

import org.springframework.validation.Errors;
import org.springframework.validation.ValidationUtils;
import org.springframework.validation.Validator;

public class StudentValidator implements Validator {

   @Override
   public boolean supports(Class<?> clazz) {
      return Student.class.isAssignableFrom(clazz);
   }

   @Override
   public void validate(Object target, Errors errors) {  
      ValidationUtils.rejectIfEmptyOrWhitespace(errors, 
         "name", "required.name","Field name is required.");
   }
}

StudentController.java

package com.tutorialspoint;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.validation.BindingResult;
import org.springframework.validation.Validator;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.WebDataBinder;
import org.springframework.web.bind.annotation.InitBinder;
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 {

   @Autowired
   @Qualifier("studentValidator")
   private Validator validator;

   @InitBinder
   private void initBinder(WebDataBinder binder) {
      binder.setValidator(validator);
   }

   @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";
   }
}

HelloWeb-servlet.xml

<beans xmlns="http://www.springframework.org/schema/beans"
   xmlns:context="http://www.springframework.org/schema/context"
   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">

   <context:component-scan base-package="com.tutorialspoint" />

   <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
      <property name="prefix" value="/WEB-INF/jsp/" />
      <property name="suffix" value=".jsp" />
   </bean>
 
   <bean id="studentValidator" class="com.tutorialspoint.StudentValidator" />
</beans>

Here the first service method student(), we have passed a blank Student object 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 student() method is called it returns addStudent.jsp view.
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 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="/HelloWeb/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>
    </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're using <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.
And We're using <form:errors /> tag with path="name" to render error message for name field. For example

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

It will render error messages for name 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 and use Export > WAR File option and save your HelloWeb.war file in Tomcat's webapps folder.
Now start your Tomcat server and make sure you are able to access other web pages from webapps folder using a standard browser. Now try a URL http://localhost:8080/HelloWeb/addStudent and you should see the following result if everything is fine with your Spring Web Application:
After submitting required information click on submit button to submit the form. You should see the following result if everything is fine with your Spring Web Application: