IntelliJIDEA Getting+Started+with+Spring+MVC,+Hibernate+and+JSON

https://confluence.jetbrains.com/display/IntelliJIDEA/Getting+Started+with+Spring+MVC,+Hibernate+and+JSON

In this tutorial we will create a simple web application using Spring MVC, Hibernate and JSON. We will use Maven to manage dependencies and IntelliJ IDEA to create, run and debug an application on local Tomcat application server.

Make sure that Spring, Maven and Tomcat plugins are enabled in IntelliJ IDEA Ultimate before you perform this tutorial.

1. Create a project

Open Project Wizard and select Spring MVC in Spring section. If you have already configured the application server, you can select it in theApplication Server field. With IntelliJ IDEA you can deploy applications to Tomcat, TomEE, Glassfish, JBoss, WebSphere, Jetty,Geronimo, Resin, Cloud Foundry and CloudBees.

Change Project name, Project location and Base package if necessary. The IDE will create a "Hello world" project with a simple controller and view.

The new project comes with Maven's pom.xml file. You can manage project dependencies through this file or through the dedicated Maventool window.

When you change Maven's dependencies, IntelliJ IDEA applies the corresponding changes to the project automatically. You can check it in the
Project Structure → Modules dialog.

Besides dependencies, IntelliJ IDEA also imports the artifacts definition from pom.xml. You can check the artifacts settings in the
Project Structure → Artifacts dialog.

The artifacts define the structure of what will be deployed to the application server when you click Run → Run 'Tomcat 7.0'.

2. Create run configuration

If you haven't specified Application server in Project Wizard you can do it now via Run → Edit Configurations....

Don't forget to specify the artifacts to deploy for this run configuration via the
Deployment tab.

If you have configured at least one run configuration for an application server, IntelliJ IDEA shows the Application Servers tool window to manage the application state on the application server. You can see the list of application servers, start or stop servers, see deployed applications, manage artifacts to deploy, and manage the application state.

3. Run the application

After the artifacts and run configurations are defined, you can deploy the application by simply running your configuration or via a shortcut right from the Application Servers tool window.

4. Add dependencies

Since we are going to create a database for our application, we need Spring Data, Hibernate and HSQLDB libraries. In order to implement JSON API for our application we need JSON library. Finally, we will need JSTL library to use in application's view.

We have to define all these dependencies in our pom.xml file. The IDE will automatically download the corresponding libraries and add to the artifact.

< dependency >
   < groupId >jstl</ groupId >
   < artifactId >jstl</ artifactId >
   < version >1.2</ version >
</ dependency >

< dependency >
< groupId >org.springframework.data</ groupId >
   < artifactId >spring-data-jpa</ artifactId >
   < version >1.2.0.RELEASE</ version >
</ dependency >

< dependency >
   < groupId >org.hibernate.javax.persistence</ groupId >
   < artifactId >hibernate-jpa-2.0-api</ artifactId >
   < version >1.0.0.Final</ version >
</ dependency >

< dependency >
   < groupId >org.hibernate</ groupId >
   < artifactId >hibernate-entitymanager</ artifactId >
   < version >3.6.10.Final</ version >
</ dependency >

< dependency >
   < groupId >org.hsqldb</ groupId >
   < artifactId >hsqldb</ artifactId >
   < version >2.2.9</ version >
</ dependency >

< dependency >
   < groupId >org.json</ groupId >
   < artifactId >json</ artifactId >
   < version >20080701</ version >
</ dependency >

5. Create persistence.xml

Now let's define resources/META-INF/persistence.xml file to initialize Hibernate's entity manager over JPA.

<? xml version = "1.0" encoding = "UTF-8" ?>
< persistence version = "2.0" xmlns = "http://java.sun.com/xml/ns/persistence" xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation = "http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd" >
    < persistence-unit name = "defaultPersistenceUnit" transaction-type = "RESOURCE_LOCAL" >
        < provider >org.hibernate.ejb.HibernatePersistence</ provider >
        < properties >
            < property name = "hibernate.dialect" value = "org.hibernate.dialect.HSQLDialect" />
            < property name = "hibernate.connection.url" value = "jdbc:hsqldb:mem:spring" />
            < property name = "hibernate.connection.driver_class" value = "org.hsqldb.jdbcDriver" />
            < property name = "hibernate.connection.username" value = "sa" />
            < property name = "hibernate.connection.password" value = "" />
            < property name = "hibernate.hbm2ddl.auto" value = "create-drop" />
        </ properties >
    </ persistence-unit >
</ persistence >

6. Define model classes

Define a model class for user entity using JPA annotations.

package com.springapp.mvc;

import javax.persistence.*;

@Entity (name = "account" )
public class User {
    @Id
    @GeneratedValue (strategy = GenerationType.AUTO)
    private Long id;

    @Basic
    private String firstName;

    @Basic
    private String lastName;

    @Basic
    private String email;

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this .id = id;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String name) {
        this .firstName = name;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this .lastName = lastName;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this .email = email;
    }
}

Define a Spring repository for the user entity.

package com.springapp.mvc;

import org.springframework.data.jpa.repository.JpaRepository;

public interface UserRepository extends JpaRepository<User, Long> {
}

7. Register repository, entity manager factory and transaction manager

Now we have to register the user repository, an entity manager factory and a transaction manager in webapp/WEB-INF/mvc-dispatcher-servlet.xmlfile.

< jpa:repositories base-package = "com.springapp.mvc" />

< bean id = "entityManagerFactory" class = "org.springframework.orm.jpa.LocalEntityManagerFactoryBean" >
    < property name = "persistenceUnitName" value = "defaultPersistenceUnit" />
</ bean >

< bean id = "transactionManager" class = "org.springframework.orm.jpa.JpaTransactionManager" >
    < property name = "entityManagerFactory" ref = "entityManagerFactory" />
</ bean >

< tx:annotation-driven transaction-manager = "transactionManager" />

The model for our application is ready, so we can implement the controller.

8. Define controller

Let's rename HelloController to UserController and add the following code:

package com.springapp.mvc;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.ModelMap;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@Controller
public class UserController {
    @Autowired
    private UserRepository userRepository;

    @RequestMapping (value = "/" , method = RequestMethod.GET)
    public String listUsers(ModelMap model) {
        model.addAttribute( "user" , new User());
        model.addAttribute( "users" , userRepository.findAll());
        return "users" ;
    }

    @RequestMapping (value = "/add" , method = RequestMethod.POST)
    public String addUser( @ModelAttribute ( "user" ) User user, BindingResult result) {

        userRepository.save(user);

        return "redirect:/" ;
    }

    @RequestMapping ( "/delete/{userId}" )
    public String deleteUser( @PathVariable ( "userId" ) Long userId) {

        userRepository.delete(userRepository.findOne(userId));

        return "redirect:/" ;
    }
}

As you can see, we have defined three methods for listing, adding and deleting user entities. The methods are mapped to the corresponding URLs.

9. Define view

Let's rename hello view (and corresponding hello.jsp file) to users (and users.jsp , respectively). If you rename the view name from usage,IntelliJ IDEA applies the corresponding changes to JSP files automatically.

<!doctype html>
<%@taglib uri="http://www.springframework.org/tags" prefix="spring" %>
<%@taglib uri="http://www.springframework.org/tags/form" prefix="form" %>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>

< html >
< head >
    < meta charset = "utf-8" >
    < title >Spring MVC Application</ title >

    < meta content = "IE=edge,chrome=1" http-equiv = "X-UA-Compatible" >
    < meta name = "viewport" content = "width=device-width, initial-scale=1.0" >

    < link href = "http://twitter.github.io/bootstrap/assets/css/bootstrap.css" rel = "stylesheet" >
    < link href = "http://twitter.github.io/bootstrap/assets/css/bootstrap-responsive.css" rel = "stylesheet" >
</ head >

< body >

< div class = "container" >
    < div class = "row" >
        < div class = "span8 offset2" >
            < h1 >Users</ h1 >
            < form:form method = "post" action = "add" commandName = "user" class = "form-horizontal" >
            < div class = "control-group" >
                < form:label cssClass = "control-label" path = "firstName" >First Name:</ form:label >
                < div class = "controls" >
                    < form:input path = "firstName" />
                </ div >
            </ div >
            < div class = "control-group" >
                < form:label cssClass = "control-label" path = "lastName" >Last Name:</ form:label >
                < div class = "controls" >
                    < form:input path = "lastName" />
                </ div >
            </ div >
            < div class = "control-group" >
                < form:label cssClass = "control-label" path = "email" >Email:</ form:label >
                < div class = "controls" >
                    < form:input path = "email" />
                </ div >
            </ div >
            < div class = "control-group" >
                < div class = "controls" >
                    < input type = "submit" value = "Add User" class = "btn" />
                    </ form:form >
                </ div >
            </ div >

            < c:if test = "${!empty users}" >
                < h3 >Users</ h3 >
                < table class = "table table-bordered table-striped" >
                    < thead >
                    < tr >
                        < th >Name</ th >
                        < th >Email</ th >
                        < th >&nbsp;</ th >
                    </ tr >
                    </ thead >
                    < tbody >
                    < c:forEach items = "${users}" var = "user" >
                        < tr >
                            < td >${user.lastName}, ${user.firstName}</ td >
                            < td >${user.email}</ td >
                            < td >
                                < form action = "delete/${user.id}" method = "post" >< input type = "submit" class = "btn btn-danger btn-mini" value = "Delete" /></ form >
                            </ td >
                        </ tr >
                    </ c:forEach >
                    </ tbody >
                </ table >
            </ c:if >
        </ div >
    </ div >
</ div >

</ body >
</ html >

10. Run the application

The application should be ready now.

11. Debug application

If you need to debug your application, just add a breakpoint and re-run the application in debug mode via Run → Debug 'Tomcat 7.0'....

12. Add JSON API

Finally, let's output the created users via JSON by implementing this simple Controller's method:

@RequestMapping (value = "/api/users" , method = RequestMethod.GET)
public
@ResponseBody
String listUsersJson(ModelMap model) throws JSONException {
    JSONArray userArray = new JSONArray();
    for (User user : userRepository.findAll()) {
        JSONObject userJSON = new JSONObject();
        userJSON.put( "id" , user.getId());
        userJSON.put( "firstName" , user.getFirstName());
        userJSON.put( "lastName" , user.getLastName());
        userJSON.put( "email" , user.getEmail());
        userArray.put(userJSON);
    }
    return userArray.toString();
}

Run the application and open http://localhost:8080/api/users.

Download the final code and IntelliJ IDEA's project files from GitHub.