Spring boot + Hibernate + Web UI (Thymeleaf)

This thread is focused on how to create a spring boot application with hibernate and thymyleaf template engine.

Hibernate Configuration

First, lets overview what we need in order to setup Hibernate correctly.

@EnableTransactionManagement and @EnableJpaRepositories - we want transactional management and to use spring data repositories.
DataSource - main datasource for the application. using in-memory h2 for this example.
LocalContainerEntityManagerFactoryBean - spring entity manager factory using HibernateJpaVendorAdapter.
PlatformTransactionManager - main transaction manager for @Transactional annotated components.

Configuration file:

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(basePackages = "com.example.repositories")
public class PersistanceJpaConfig {

    @Bean
    public DataSource dataSource() {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName("org.h2.Driver");
        dataSource.setUrl("jdbc:h2:mem:testdb;mode=MySQL;DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=FALSE");
        dataSource.setUsername("sa");
        dataSource.setPassword("");
        return dataSource;
    }

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory(DataSource dataSource) {
        LocalContainerEntityManagerFactoryBean em = new LocalContainerEntityManagerFactoryBean();
        em.setDataSource(dataSource);
        em.setPackagesToScan(new String[] { "com.example.models" });
        JpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        em.setJpaVendorAdapter(vendorAdapter);
        em.setJpaProperties(additionalProperties());
        return em;
    }

    @Bean
    public PlatformTransactionManager transactionManager(LocalContainerEntityManagerFactoryBean entityManagerFactory, DataSource dataSource) {
        JpaTransactionManager tm = new JpaTransactionManager();
        tm.setEntityManagerFactory(entityManagerFactory.getObject());
        tm.setDataSource(dataSource);
        return tm;
    }

    Properties additionalProperties() {
        Properties properties = new Properties();
        properties.setProperty("hibernate.hbm2ddl.auto", "update");
        properties.setProperty("hibernate.dialect", "org.hibernate.dialect.H2Dialect");
        return properties;
    }

}

Entities and Repositories

A simple entity: Using Lombok @Getter and @Setter annotations to generate getters and setters for us

@Entity
@Getter @Setter
public class Message {

    @Id
    @GeneratedValue(generator = "system-uuid")
    @GenericGenerator(name = "system-uuid", strategy = "uuid")
    private String id;
    private String message;

}

I am using UUID based ids and lombok to generate getters and setters.

A simple repository for the entity above:

@Transactional
public interface MessageRepository extends CrudRepository<Message, String> {
}

Maven dependencies

This example is based on spring boot 1.5.1.RELEASE. with the following dependencies:

<!-- Spring -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-thymeleaf</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!-- Lombok -->
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <optional>true</optional>
</dependency>
<!-- H2 -->
<dependency>
    <groupId>com.h2database</groupId>
    <artifactId>h2</artifactId>
</dependency>
<!-- Test -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
</dependency>

In this example we are going to use Spring Boot JPA, Thymeleaf and web starters. I am using Lombok to generate getters and setters easier but it is not mandatory. H2 will be used as an in-memory easy to configure database.

Thymeleaf Resources and Spring Controller

In order to expose Thymeleaf templates we need to define controllers.

Example:

@Controller
@RequestMapping("/")
public class MessageController {

    @Autowired
    private MessageRepository messageRepository;

    @GetMapping
    public ModelAndView index() {
        Iterable<Message> messages = messageRepository.findAll();
        return new ModelAndView("index", "index", messages);
    }

}

This simple controller injects MessageRepository and pass all messages to a template file named index.html, residing in src/main/resources/templates, and finally expose it on /index.

In the same way, we can place other templates in the templates folder (default by spring to src/main/resources/templates), pass a model to them and serve them to the client.

Other static resources should be placed in one of the following folders, exposed by default in spring boot:

/META-INF/resources/
/resources/
/static/
/public/

Thymeleaf index.html example:

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
    <head th:fragment="head (title)">
        <title th:text="${title}">Index</title>
        <link rel="stylesheet" th:href="@{/css/bootstrap.min.css}" href="../../css/bootstrap.min.css" />
    </head>
    <body>
        <nav class="navbar navbar-default navbar-fixed-top">
          <div class="container-fluid">
            <div class="navbar-header">
              <a class="navbar-brand" href="#">Thymeleaf</a>
            </div>
          </div>
        </nav>
        <div class="container">
            <ul class="nav">
                <li><a th:href="@{/}" href="messages.html"> Messages </a></li>
            </ul>
        </div>
    </body>
</html>

bootstrap.min.css is in src/main/resources/static/css folder. you can use the syntax @{} to get other static resources using relative path.

Remarks

Also check the Thymeleaf documentation