In this tutorial, we will learn how to use Spring Boot with Spring data JPA to save data into an H2 in-memory database and how to also how to query the data.
Final Project Structure : Will look like this
1. Add Maven Dependency Or use Spring Initializr
Add the 3 dependencies :
- Spring Data jpa
- H2 in-memory database
- Spring web – for tomcat
and generate the project if using spring initializr Or you can also add them directly to spring boot pom.
So the pom.xml file will look like this.
<?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>2.2.4.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.programmertoday</groupId>
<artifactId>spring-boot-data</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>spring-boot-data</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>com.h2database</groupId>
<artifactId>h2</artifactId>
<scope>runtime</scope>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</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>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>2. Create : Spring Data Entity
Create an entity called Employee.class
package com.programmertoday.entities;
import javax.persistence.*;
import java.io.Serializable;
@Entity
@Table(name = "Employee")
public class Employee implements Serializable {
private static final long serialVersionUID = -1798070786993154676L;
@Id
private Integer id;
@Column(name="name")
private String name;
@Column(name="address")
private String address;
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 getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
}
3. Spring Data Repository
Create a Spring Data Repository Interface like below and go to the next step.
Here we created a Repository which Spring Data JPA has provided and extend a CrudRepository which provides us some boilerplate code and functionalities which helps us interact with the database just like a normal JPA or Hibernate would do.
package com.programmertoday.repositories;
import com.programmertoday.entities.Employee;
import org.springframework.data.repository.CrudRepository;
public interface EmployeeRepository extends CrudRepository<Employee,Integer> {
}
4. Connection with H2 in-memory database
1.> Just add the below 2 properties for h2 db in application.properties file :
spring.h2.console.enabled=true
spring.h2.console.path=/h2
2.> Also, Just For Testing Create two sample .sql scripts to create an Employee table and insert 2 records into that table on application load or startup.
Create 2 scripts as shown in the snapshot below:
Script.sql
Drop table if exists Employee; Create table (id number , string name, string address);
Data.sql
insert into Employee (id,name,address) values (1,'John','US'); insert into Employee (id,name,address) values (2,'Mak','UK');
5. Run Main method – @SpringBootApplication
Now just open the main class and run it.
Voila !
Your SpringBoot Spring Data JPA application is up and running @ <localhost:port>
Default port will be 8080 [ example : localhost:8080 ]
When you run the main class of SpringBootApplication, you see the below log in the console which also tells you that the h2 in-memory data base is up and runnning at url “localhost:port/h2”
2020-01-26 21:11:55.948 INFO 22204 — [ main] o.s.b.a.h2.H2ConsoleAutoConfiguration : H2 console available at ‘/h2’. Database available at ‘jdbc:h2:mem:testdb’
Open h2 db : localhost:8080/h2
Summary
In this tutorial, we learnt about Spring boot connectivity with H2 DB an in-memory database along with Spring DATA JPA as a JPA framework. We connected with H2 in-memory database to save/persist data into the database and it’s easy to test.
Hope you liked it !
