Spring boot H2 Database example

Table of Contents

What is H2 database?
Tools used
Github Source code:
Project Structure
Create new Spring boot project
Maven configuration
H2 database configuration
Override H2 databse defaults
Model
Repository
Service
Controller
Spring boot main file
Run the application
Test the application

In this post, we are going to see how to create Spring boot application integrating with H2 database.

What is H2 database?

H2 is open source database. It is very fast and smaller in size. It is in-memory database and keeps all data in memory. If you start and stop the application, all the data will be erased as it is not persisted. Although there is an option to persist the data on the disk as well with H2 database.

H2 database is not recommended for production environment and is suitable for small applications which require very simple database.

Tools used

Spring Boot 2.2.2.RELEASE
Spring JDBC 5.2.2.RELEASE
HikariCP 3.4.1
Maven 3
Java 8

Github Source code:

Download

Here are steps to create a Spring boot H2 database example.

Project Structure

SpringH2DatabaseProjectStructure

Create new Spring boot project

Step 1: Go to start.spring.io and create a project with following dependencies

Spring web
H2 database
Spring data jpa

Here is the screenshot for the same.
Spring Boot Spring io

Maven configuration

Step 2: You should have pom.xml as below:


<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.2.RELEASE</version>
        <relativePath /> <!-- lookup parent from repository -->
    </parent>
    <groupId>org.arpit.java2blog</groupId>
    <artifactId>SpringBootH2Example</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>SpringBootH2Example</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.junit.vintage</groupId>
                    <artifactId>junit-vintage-engine</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-devtools -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

<?xml version="1.0" encoding="UTF-8"?>

<project xmlns="http://maven.apache.org/POM/4.0.0"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-parent</artifactId>

<version>2.2.2.RELEASE</version>

</parent>

<groupId>org.arpit.java2blog</groupId>

<artifactId>SpringBootH2Example</artifactId>

<version>0.0.1-SNAPSHOT</version>

<name>SpringBootH2Example</name>

<description>Demo project for Spring Boot</description>

<java.version>1.8</java.version>

</properties>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-data-jpa</artifactId>

</dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-web</artifactId>

</dependency>

<groupId>com.h2database</groupId>

</dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-starter-test</artifactId>

<groupId>org.junit.vintage</groupId>

<artifactId>junit-vintage-engine</artifactId>

</exclusion>

</exclusions>

</dependency>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-devtools</artifactId>

</dependency>

</dependencies>

<build>

<groupId>org.springframework.boot</groupId>

<artifactId>spring-boot-maven-plugin</artifactId>

</plugin>

</plugins>

</build>

</project>

The spring-boot-starter-parent provides you all maven defaults required for any spring project.

H2 database configuration

As we already know Spring boot is opinionated framework and it will do lots of autoconfigurations based on dependencies available in class path.

In this case, we have H2 dependencies in our classpath, so Spring boot automatically configures some default properties such as URL, username and password.

spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=
spring.jpa.database-platform=org.hibernate.dialect.H2Dialect

We don’t have to configure anything in case you are fine with these defaults. It uses schema name as testdb.

Can we override defaults?
Oh yes, you can

Override H2 databse defaults

You can always override any property by putting it in application.properties.
For example:
Let’s say you want override property spring.h2.console.enable and want to change it true
You can put this property in application.properties as below.


spring.h2.console.enable=true

spring.h2.console.enable=true

Model

Step 3: Create model class named Movie.java


package org.arpit.java2blog.model;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;

@Entity
public class Movie {

        @Id
        @GeneratedValue
        private int id;
        private String name;
        private String genre;
        public int getId() {
            return id;
        }
        public void setId(int id) {
            this.id = id;
        }
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
        public String getGenre() {
            return genre;
        }
        public void setGenre(String genre) {
            this.genre = genre;
        }
}

package org.arpit.java2blog.model;

import javax.persistence.Entity;

import javax.persistence.GeneratedValue;

import javax.persistence.Id;

@Entity

public class Movie {

@Id

@GeneratedValue

private int id;

private String name;

private String genre;

public int getId() {

return id;

}

public void setId(int id) {

this.id = id;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public String getGenre() {

return genre;

}

public void setGenre(String genre) {

this.genre = genre;

}

@Entity is used for making a persistent pojo class.For this java class,you will have corresponding table in database.

Repository

Step 4: Create a MovieRepository interface which will extend CrudRepository. We don’t have to provide implementaton, Spring data will autmatically do it for us.


package org.arpit.java2blog.repository;

import org.arpit.java2blog.model.Movie;
import org.springframework.data.repository.CrudRepository;

public interface MovieRepository extends CrudRepository<Movie, Integer> {}

package org.arpit.java2blog.repository;

import org.arpit.java2blog.model.Movie;

import org.springframework.data.repository.CrudRepository;

public interface MovieRepository extends CrudRepository<Movie, Integer> {}

Service

Step 5: Create a service class “MovieService” and autowire MovieRepository in service class.


package org.arpit.java2blog.service;
import java.util.ArrayList;
import java.util.List;

import org.arpit.java2blog.model.Movie;
import org.arpit.java2blog.repository.MovieRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class MovieService {

    @Autowired
    MovieRepository movieRepository;

    public List getAllMovies() {
        List movies = new ArrayList();
        movieRepository.findAll().forEach(movie -> movies.add(movie));
        return movies;
    }

    public Movie getMovieById(int id) {
        return movieRepository.findById(id).get();
    }

    public void saveOrUpdate(Movie mvoie) {
        movieRepository.save(mvoie);
    }

    public void delete(int id) {
        movieRepository.deleteById(id);
    }
}

package org.arpit.java2blog.service;

import java.util.ArrayList;

import java.util.List;

import org.arpit.java2blog.model.Movie;

import org.arpit.java2blog.repository.MovieRepository;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.stereotype.Service;

@Service

public class MovieService {

@Autowired

MovieRepository movieRepository;

public List getAllMovies() {

List movies = new ArrayList();

movieRepository.findAll().forEach(movie -> movies.add(movie));

return movies;

}

public Movie getMovieById(int id) {

return movieRepository.findById(id).get();

}

public void saveOrUpdate(Movie mvoie) {

movieRepository.save(mvoie);

}

public void delete(int id) {

movieRepository.deleteById(id);

}

Controller

Step 6: Create a file named “MovieController.java” in package .org.arpit.java2blog.controller and autowire MovieService in MovieController.


package org.arpit.java2blog.controller;
import java.util.List;

import org.arpit.java2blog.model.Movie;
import org.arpit.java2blog.service.MovieService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class MovieController {

    @Autowired
    MovieService movieService;

    @GetMapping("/movies")
    private List getAllMovies() {
        return movieService.getAllMovies();
    }

    @GetMapping("/movies/{id}")
    private Movie getMovie(@PathVariable("id") int id) {
        return movieService.getMovieById(id);
    }

    @DeleteMapping("/movies/{id}")
    private void deleteMovie(@PathVariable("id") int id) {
        movieService.delete(id);
    }

    @PostMapping("/movies")
    private int saveMovie(@RequestBody Movie movie) {
        movieService.saveOrUpdate(movie);
        return movie.getId();
    }
}

package org.arpit.java2blog.controller;

import java.util.List;

import org.arpit.java2blog.model.Movie;

import org.arpit.java2blog.service.MovieService;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.web.bind.annotation.DeleteMapping;

import org.springframework.web.bind.annotation.GetMapping;

import org.springframework.web.bind.annotation.PathVariable;

import org.springframework.web.bind.annotation.PostMapping;

import org.springframework.web.bind.annotation.RequestBody;

import org.springframework.web.bind.annotation.RestController;

@RestController

public class MovieController {

@Autowired

MovieService movieService;

@GetMapping("/movies")

private List getAllMovies() {

return movieService.getAllMovies();

}

@GetMapping("/movies/{id}")

private Movie getMovie(@PathVariable("id") int id) {

return movieService.getMovieById(id);

}

@DeleteMapping("/movies/{id}")

private void deleteMovie(@PathVariable("id") int id) {

movieService.delete(id);

}

@PostMapping("/movies")

private int saveMovie(@RequestBody Movie movie) {

movieService.saveOrUpdate(movie);

return movie.getId();

}

Spring boot main file

Step 7: Create a file named SpringBootH2ExampleApplication.java in package .org.arpit.java2blog


package org.arpit.java2blog;
package org.arpit.java2blog;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class SpringBootH2ExampleApplication {

    public static void main(String[] args) {
        SpringApplication.run(SpringBootH2ExampleApplication.class, args);
    }

}

package org.arpit.java2blog;

import org.springframework.boot.SpringApplication;

import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication

public class SpringBootH2ExampleApplication {

public static void main(String[] args) {

SpringApplication.run(SpringBootH2ExampleApplication.class, args);

}

We have just added @SpringBootApplication and it does all the work.
Let’s understand more about this annotation.
@SpringBootApplication is an annotation that adds all of the following:

@Configuration makes the class as a source of bean definitions for the application context.
@EnableAutoConfiguration enables Spring boot to add beans present in classpath setting and various property setting.

Normally you would add @EnableWebMvc for a Spring MVC application, but Spring Boot adds it automatically when it sees spring-webmvc on the classpath.
This flags the application as a web application and activates key behaviors such as setting up a DispatcherServlet.

@ComponentScan tells Spring to look for other components, configurations, and services in the default package, allowing it to find the controllers.
If specific packages are not defined, scanning will occur from the package of the class that declares this annotation.

Run the application

Step 8: Let’s start and run the appliation.
Let’s open H2 console now.

Go to url http://localhost:8080/h2-console

SpringBootH2DatabaseURL
Please make sure JDBC URL is jdbc:h2:mem:testdb

Click on connect
You should be able to see Movie table as below

SpringBootH2MovieTable

Test the application

Step 9:
We will test this application in postman , UI based client for testing restful web applications. It is chrome plugin. Launch postman.If you want java based client, then you can also use how to send get or post request in java.

Create movie object

Launch postman
Select request type as Post
Set URL as http://localhost:8080/movies
Go to header and put content-type=application/json as key value pair
Go to Body,select raw and paste {
“name”: “The Godfather”,
“genre”: “Drama”
}
Click on send

SpringBootH2Post
Here is screenshot of H2 database table.
SpringBootH2MovieGodFather
Once you create on send, let’s check if we have entry in H2 database.
I have created few more movies object with below json with similar post request

{
“name”:”Inception”,
“genre”:”Action”
}{
“name”:”The Hangover”,
“genre”:”Comedy”
}{
“name”:”Forrest Gump”,
“genre”:”Comedy”
}

Here are records in database after above post requests.

Get all movie objects

Launch postman
Select request type as Get
Set URL as http://localhost:8080/movies
Click on send

SpringBootH2GetMovies

Delete movie id 3

Launch postman
Select request type as Delete
Set URL as http://localhost:8080/movies/3
Click on send

SpringH2Delete
Let’s get all the movies again after deleting movie with id 3

That’s all about Spring boot H2 database example

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Spring boot H2 Database example

What is H2 database?

Tools used

Github Source code:

Project Structure

Create new Spring boot project

Maven configuration

H2 database configuration

Override H2 databse defaults

Model

Repository

Service

Controller

Spring boot main file

Run the application

Test the application

Create movie object

Get all movie objects

Delete movie id 3

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What is H2 database?

Tools used

Github Source code:

Project Structure

Create new Spring boot project

Maven configuration

H2 database configuration

Override H2 databse defaults

Model

Repository

Service

Controller

Spring boot main file

Run the application

Test the application

Create movie object

Get all movie objects

Delete movie id 3

Was this post helpful?

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