Spring MVC Error Handling Example - Spring MVC Framework

What is Spring MVC - Error Handling Example?

The following example explains the readers on how to use Error Handling and Validatorsin forms using Spring Web MVC framework. Firstly, a working Eclipse IDE should be in place and follow the steps below to create a Dynamic Form based Web Application

Student.java

package com.wisdomjobs; 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.wisdomjobs; 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.wisdomjobs; 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.wisdomjobs" /> <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.wisdomjobs.StudentValidator" /> </beans>

In the above example, we are creating a service method called student(). We are passing a blank Student object in ModelAndView object. In this object, command name is specified because the framework expects an object with “command” name if we are using <form:form> tags in JSP file. addStudent.jsp view is returned if student() method is called.

addStudent() is the next method which is called against a POST method on HelloWeb/addStudent URL. Model object is prepared based on the submitted information. A “result” view is returned from service method at the end which results in showing result.jsp. If any errors occurred during validation then “addStudent” view is returned. BindingResult is used to inject errors automatically 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>

We use<form:errors />tag with path=”*” to display error messages. Example below-

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

It will present the error messages for all the input validations.

Also we use <form:errors /> tag with path="name" to present error message for the name field. Example below-

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

It will present the error messages for the 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 the source and configuration files are created export the application. Do right click on the application and Export > WAR File option and save HelloWeb.war file in Tomcat’s webapps folder.

Start the Tomcat Server and using a standard browser check if you are having access to other web pages from webapps folder. Try the URL http://localhost:8080/HelloWeb/addStudent and you must see the below result if everything is fine with Spring Web Application:

Submit the form once the required information is filled by clicking Submit button. You must see the below result if everything is fine with Spring Web Application: