Spring MVC - Error Handpng Example

The following example shows how to use Error Handpng and Vapdators in forms using the Spring Web MVC Framework. To start with, let us have a working Ecppse IDE in place and consider the following steps to develop a Dynamic Form based Web Apppcation using the Spring Web Framework.

Student.java

package com.tutorialspoint;

pubpc class Student {
   private Integer age;
   private String name;
   private Integer id;

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

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

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

StudentVapdator.java

package com.tutorialspoint;

import org.springframework.vapdation.Errors;
import org.springframework.vapdation.VapdationUtils;
import org.springframework.vapdation.Vapdator;

pubpc class StudentVapdator implements Vapdator {

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

   @Override
   pubpc void vapdate(Object target, Errors errors) {		
      VapdationUtils.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.Quapfier;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.vapdation.BindingResult;
import org.springframework.vapdation.Vapdator;
import org.springframework.vapdation.annotation.Vapdated;
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
pubpc class StudentController {

   @Autowired
   @Quapfier("studentVapdator")
   private Vapdator vapdator;

   @InitBinder
   private void initBinder(WebDataBinder binder) {
      binder.setVapdator(vapdator);
   }

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

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

   @RequestMapping(value = "/addStudent", method = RequestMethod.POST)
   pubpc String addStudent(@ModelAttribute("student") @Vapdated 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 = "studentVapdator" class = "com.tutorialspoint.StudentVapdator" />
</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 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 vapdator then same view "addStudent" is returned, Spring automatically injects error messages from BindingResult in view.

addStudent.jsp

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

      .errorblock {
         color: #000;
         background-color: #ffEEEE;
         border: 3px sopd #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 = "span" />
         <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 are using <form:errors /> tag with path="*" to render error messages. For example

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

It will render the error messages for all input vapdations.

We are 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 the name field vapdations.

result.jsp

<%@tagpb uri = "http://www.springframework.org/tags/form" prefix = "form"%>
<html>
   <head>
      <title>Spring MVC Form Handpng</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 apppcation. Right cpck on your apppcation, use Export → WAR File option and save the HelloWeb.war file in Tomcat s webapps folder.

Now, start your Tomcat server and make sure you are able to access other webpages from webapps folder using a standard browser. Try a URL − http://localhost:8080/HelloWeb/addStudent and we will see the following screen, if everything is fine with the Spring Web Apppcation.

After submitting the required information, cpck on the submit button to submit the form. You should see the following screen, if everything is fine with the Spring Web Apppcation.