In this tutorial, we will show you how to use Spring Boot + Spring data JPA to save data into an H2 in-memory database and how to also query the data.
Technologies used :
- Spring Boot 2.1.2.RELEASE
- Spring 5.1.4.RELEASE
- Hibernate 5.3.7
- HikariCP 3.2.0
- H2 in-memory database 1.4.197
- Maven 3
- Java 8
Note
By default, Spring Boot 2 uses HikariCP as the database connection pool. Read this Spring Boot algorithm to choose a pool implementation.
1. Project Directory
2. Maven
Puts spring-boot-starter-data-jpa, it will get Spring data, Hibernate, HikariCP and all databases related dependencies.
pom.xml
<?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
http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<artifactId>spring-data-jpa</artifactId>
<packaging>jar</packaging>
<name>Spring Boot Spring Data JPA</name>
<version>1.0</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.1.2.RELEASE</version>
</parent>
<properties>
<java.version>1.8</java.version>
<downloadSources>true</downloadSources>
<downloadJavadocs>true</downloadJavadocs>
</properties>
<dependencies>
<!-- jpa, crud repository -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<!-- in-memory database -->
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.22.0</version>
</plugin>
</plugins>
</build>
</project>
Display the project dependencies.
$ mvn dependency:tree
[INFO] org.springframework.boot:spring-boot-data-jpa:jar:1.0
[INFO] +- org.springframework.boot:spring-boot-starter-data-jpa:jar:2.1.2.RELEASE:compile
[INFO] | +- org.springframework.boot:spring-boot-starter-aop:jar:2.1.2.RELEASE:compile
[INFO] | | +- org.springframework:spring-aop:jar:5.1.4.RELEASE:compile
[INFO] | | \- org.aspectj:aspectjweaver:jar:1.9.2:compile
[INFO] | +- org.springframework.boot:spring-boot-starter-jdbc:jar:2.1.2.RELEASE:compile
[INFO] | | +- com.zaxxer:HikariCP:jar:3.2.0:compile
[INFO] | | \- org.springframework:spring-jdbc:jar:5.1.4.RELEASE:compile
[INFO] | +- javax.transaction:javax.transaction-api:jar:1.3:compile
[INFO] | +- javax.xml.bind:jaxb-api:jar:2.3.1:compile
[INFO] | | \- javax.activation:javax.activation-api:jar:1.2.0:compile
[INFO] | +- org.hibernate:hibernate-core:jar:5.3.7.Final:compile
[INFO] | | +- org.jboss.logging:jboss-logging:jar:3.3.2.Final:compile
[INFO] | | +- javax.persistence:javax.persistence-api:jar:2.2:compile
[INFO] | | +- org.javassist:javassist:jar:3.23.1-GA:compile
[INFO] | | +- net.bytebuddy:byte-buddy:jar:1.9.7:compile
[INFO] | | +- antlr:antlr:jar:2.7.7:compile
[INFO] | | +- org.jboss:jandex:jar:2.0.5.Final:compile
[INFO] | | +- com.fasterxml:classmate:jar:1.4.0:compile
[INFO] | | +- org.dom4j:dom4j:jar:2.1.1:compile
[INFO] | | \- org.hibernate.common:hibernate-commons-annotations:jar:5.0.4.Final:compile
[INFO] | +- org.springframework.data:spring-data-jpa:jar:2.1.4.RELEASE:compile
[INFO] | | +- org.springframework.data:spring-data-commons:jar:2.1.4.RELEASE:compile
[INFO] | | +- org.springframework:spring-orm:jar:5.1.4.RELEASE:compile
[INFO] | | +- org.springframework:spring-context:jar:5.1.4.RELEASE:compile
[INFO] | | | \- org.springframework:spring-expression:jar:5.1.4.RELEASE:compile
[INFO] | | +- org.springframework:spring-tx:jar:5.1.4.RELEASE:compile
[INFO] | | +- org.springframework:spring-beans:jar:5.1.4.RELEASE:compile
[INFO] | | \- org.slf4j:slf4j-api:jar:1.7.25:compile
[INFO] | \- org.springframework:spring-aspects:jar:5.1.4.RELEASE:compile
[INFO] +- com.h2database:h2:jar:1.4.197:compile
[INFO] \- org.springframework.boot:spring-boot-starter-test:jar:2.1.2.RELEASE:test
[INFO] +- org.springframework.boot:spring-boot-starter:jar:2.1.2.RELEASE:compile
[INFO] | +- org.springframework.boot:spring-boot:jar:2.1.2.RELEASE:compile
[INFO] | +- org.springframework.boot:spring-boot-autoconfigure:jar:2.1.2.RELEASE:compile
[INFO] | +- org.springframework.boot:spring-boot-starter-logging:jar:2.1.2.RELEASE:compile
[INFO] | | +- ch.qos.logback:logback-classic:jar:1.2.3:compile
[INFO] | | | \- ch.qos.logback:logback-core:jar:1.2.3:compile
[INFO] | | +- org.apache.logging.log4j:log4j-to-slf4j:jar:2.11.1:compile
[INFO] | | | \- org.apache.logging.log4j:log4j-api:jar:2.11.1:compile
[INFO] | | \- org.slf4j:jul-to-slf4j:jar:1.7.25:compile
[INFO] | +- javax.annotation:javax.annotation-api:jar:1.3.2:compile
[INFO] | \- org.yaml:snakeyaml:jar:1.23:runtime
[INFO] +- org.springframework.boot:spring-boot-test:jar:2.1.2.RELEASE:test
[INFO] +- org.springframework.boot:spring-boot-test-autoconfigure:jar:2.1.2.RELEASE:test
[INFO] +- com.jayway.jsonpath:json-path:jar:2.4.0:test
[INFO] | \- net.minidev:json-smart:jar:2.3:test
[INFO] | \- net.minidev:accessors-smart:jar:1.2:test
[INFO] | \- org.ow2.asm:asm:jar:5.0.4:test
[INFO] +- junit:junit:jar:4.12:test
[INFO] +- org.assertj:assertj-core:jar:3.11.1:test
[INFO] +- org.mockito:mockito-core:jar:2.23.4:test
[INFO] | +- net.bytebuddy:byte-buddy-agent:jar:1.9.7:test
[INFO] | \- org.objenesis:objenesis:jar:2.6:test
[INFO] +- org.hamcrest:hamcrest-core:jar:1.3:test
[INFO] +- org.hamcrest:hamcrest-library:jar:1.3:test
[INFO] +- org.skyscreamer:jsonassert:jar:1.5.0:test
[INFO] | \- com.vaadin.external.google:android-json:jar:0.0.20131108.vaadin1:test
[INFO] +- org.springframework:spring-core:jar:5.1.4.RELEASE:compile
[INFO] | \- org.springframework:spring-jcl:jar:5.1.4.RELEASE:compile
[INFO] +- org.springframework:spring-test:jar:5.1.4.RELEASE:test
[INFO] \- org.xmlunit:xmlunit-core:jar:2.6.2:test3. Spring Data JPA
Book.java
package com.favtuts;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
@Entity
public class Book {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private Long id;
private String name;
public Book() {
}
public Book(String name) {
this.name = name;
}
//getters, setters, toString...
}
BookRepository.java
package com.favtuts;
import org.springframework.data.repository.CrudRepository;
import java.util.List;
public interface BookRepository extends CrudRepository<Book, Long> {
List<Book> findByName(String name);
}
4. @SpringBootApplication
4.1 Start Spring Boot, inserts 3 books into the H2 database, and test the find() method.
StartApplication.java
package com.favtuts;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class StartApplication implements CommandLineRunner {
private static final Logger log = LoggerFactory.getLogger(StartApplication.class);
@Autowired
private BookRepository repository;
public static void main(String[] args) {
SpringApplication.run(StartApplication.class, args);
}
@Override
public void run(String... args) {
log.info("StartApplication...");
repository.save(new Book("Java"));
repository.save(new Book("Node"));
repository.save(new Book("Python"));
System.out.println("\nfindAll()");
repository.findAll().forEach(x -> System.out.println(x));
System.out.println("\nfindById(1L)");
repository.findById(1l).ifPresent(x -> System.out.println(x));
System.out.println("\nfindByName('Node')");
repository.findByName("Node").forEach(x -> System.out.println(x));
}
}
5. HikariCP Connection Pool
By default, Spring Boot 2 uses HikariCP as the default connection pool.
5.1 Enable the logging level of com.zaxxer to debug, it will print out the default HikariCP configuration.
application.properties
logging.level.org.springframework=INFO
logging.level.com.favtuts=INFO
logging.level.com.zaxxer=DEBUG
logging.level.root=ERROR5.2 Run the Spring Boot, review the logging :
DEBUG com.zaxxer.hikari.HikariConfig - Driver class org.h2.Driver found in Thread context class loader jdk.internal.loader.ClassLoaders$AppClassLoader@28c97a5
DEBUG com.zaxxer.hikari.HikariConfig - HikariPool-1 - configuration:
DEBUG com.zaxxer.hikari.HikariConfig - allowPoolSuspension.............false
DEBUG com.zaxxer.hikari.HikariConfig - autoCommit......................true
DEBUG com.zaxxer.hikari.HikariConfig - catalog.........................none
DEBUG com.zaxxer.hikari.HikariConfig - connectionInitSql...............none
DEBUG com.zaxxer.hikari.HikariConfig - connectionTestQuery.............none
DEBUG com.zaxxer.hikari.HikariConfig - connectionTimeout...............30000
DEBUG com.zaxxer.hikari.HikariConfig - dataSource......................none
DEBUG com.zaxxer.hikari.HikariConfig - dataSourceClassName.............none
DEBUG com.zaxxer.hikari.HikariConfig - dataSourceJNDI..................none
DEBUG com.zaxxer.hikari.HikariConfig - dataSourceProperties............{password=<masked>}
DEBUG com.zaxxer.hikari.HikariConfig - driverClassName................."org.h2.Driver"
DEBUG com.zaxxer.hikari.HikariConfig - healthCheckProperties...........{}
DEBUG com.zaxxer.hikari.HikariConfig - healthCheckRegistry.............none
DEBUG com.zaxxer.hikari.HikariConfig - idleTimeout.....................600000
DEBUG com.zaxxer.hikari.HikariConfig - initializationFailTimeout.......1
DEBUG com.zaxxer.hikari.HikariConfig - isolateInternalQueries..........false
DEBUG com.zaxxer.hikari.HikariConfig - jdbcUrl.........................jdbc:h2:mem:testdb;DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=FALSE
DEBUG com.zaxxer.hikari.HikariConfig - leakDetectionThreshold..........0
DEBUG com.zaxxer.hikari.HikariConfig - maxLifetime.....................1800000
DEBUG com.zaxxer.hikari.HikariConfig - maximumPoolSize.................10
DEBUG com.zaxxer.hikari.HikariConfig - metricRegistry..................none
DEBUG com.zaxxer.hikari.HikariConfig - metricsTrackerFactory...........none
DEBUG com.zaxxer.hikari.HikariConfig - minimumIdle.....................10
DEBUG com.zaxxer.hikari.HikariConfig - password........................<masked>
DEBUG com.zaxxer.hikari.HikariConfig - poolName........................"HikariPool-1"
DEBUG com.zaxxer.hikari.HikariConfig - readOnly........................false
DEBUG com.zaxxer.hikari.HikariConfig - registerMbeans..................false
DEBUG com.zaxxer.hikari.HikariConfig - scheduledExecutor...............none
DEBUG com.zaxxer.hikari.HikariConfig - schema..........................none
DEBUG com.zaxxer.hikari.HikariConfig - threadFactory...................internal
DEBUG com.zaxxer.hikari.HikariConfig - transactionIsolation............default
DEBUG com.zaxxer.hikari.HikariConfig - username........................"sa"
DEBUG com.zaxxer.hikari.HikariConfig - validationTimeout...............5000
INFO com.zaxxer.hikari.HikariDataSource - HikariPool-1 - Starting...
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection conn0: url=jdbc:h2:mem:testdb user=SA
INFO com.zaxxer.hikari.HikariDataSource - HikariPool-1 - Start completed.
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Pool stats (total=1, active=0, idle=1, waiting=0)
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection conn1: url=jdbc:h2:mem:testdb user=SA
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection conn2: url=jdbc:h2:mem:testdb user=SA
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection conn3: url=jdbc:h2:mem:testdb user=SA
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection conn4: url=jdbc:h2:mem:testdb user=SA
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection conn5: url=jdbc:h2:mem:testdb user=SA
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection conn6: url=jdbc:h2:mem:testdb user=SA
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection conn7: url=jdbc:h2:mem:testdb user=SA
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection conn8: url=jdbc:h2:mem:testdb user=SA
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - Added connection conn9: url=jdbc:h2:mem:testdb user=SA
DEBUG com.zaxxer.hikari.pool.HikariPool - HikariPool-1 - After adding stats (total=10, active=0, idle=10, waiting=0)5.2 We can use spring.datasource.hikari.* to override the default settings.
application.properties
logging.level.org.springframework=INFO
logging.level.com.favtuts=INFO
logging.level.com.zaxxer=DEBUG
logging.level.root=ERROR
spring.datasource.hikari.connectionTimeout=20000
spring.datasource.hikari.maximumPoolSize=5
spring.datasource.hikari.poolName=HikariPoolZZZ6. Unit Test
6.1 @DataJpaTest and TestEntityManager to test a Spring data JPA repository.
BookRepositoryTest.java
package com.favtuts;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
import org.springframework.boot.test.autoconfigure.orm.jpa.TestEntityManager;
import org.springframework.test.context.junit4.SpringRunner;
import java.util.List;
import static org.assertj.core.api.Assertions.assertThat;
import static org.junit.Assert.assertEquals;
@RunWith(SpringRunner.class)
@DataJpaTest
public class BookRepositoryTest {
@Autowired
private TestEntityManager entityManager;
@Autowired
private BookRepository repository;
@Test
public void testFindByName() {
entityManager.persist(new Book("C++"));
List<Book> books = repository.findByName("C++");
assertEquals(1, books.size());
assertThat(books).extracting(Book::getName).containsOnly("C++");
}
}
7. Demo
$ mvn spring-boot:run
INFO com.favtuts.StartApplication - Started StartApplication in 2.79 seconds (JVM running for 10.883)
INFO com.favtuts.StartApplication - StartApplication...
findAll()
DEBUG com.zaxxer.hikari.pool.PoolBase - HikariPoolZZZ - Reset (readOnly) on connection conn0: url=jdbc:h2:mem:testdb user=SA
Book{id=1, name='Java'}
Book{id=2, name='Node'}
Book{id=3, name='Python'}
findById(1L)
DEBUG com.zaxxer.hikari.pool.PoolBase - HikariPoolZZZ - Reset (readOnly) on connection conn0: url=jdbc:h2:mem:testdb user=SA
Book{id=1, name='Java'}
findByName('Node')
Book{id=2, name='Node'}Download Source Code
$ git clone https://github.com/favtuts/java-spring-boot-tutorials.git
$ cd spring-data-jpa
$ mvn spring-boot:run