TechNotes Central: December 2023

In this blog post, we'll explore the configuration and setup for a Spring Boot 3 application with Java 21 that uses multiple data sources. This setup is useful when dealing with databases of different types, such as MySQL, Oracle, and PostgreSQL.

Technology

Spring Boot 3.2.0
Java 21 (Zulu)
Docker Compose
Maven
IntelliJ IDEA 2023.3.1 Community
Postman

Project Structure

multiple-data-sources-jpa
|-- src
|   |-- main
|       |-- java
|           |-- com
|               |-- henry
|                   |-- configuration
|                   |-- model
|                   |-- repository
|                   |-- service
|                   |-- controller
|-- src
|   |-- test
|       |-- java
|           |-- com
|               |-- henry
|                   |-- ...
|-- pom.xml

Application.yaml Configuration

The application file contains configuration deatils for each data source, including URLs, usernames, passowrds, and driver class names.

server:
  port: 9000
  servlet:
    context-path: /

spring:
  datasource:
    mysql:
      url: jdbc:mysql://localhost:3306/test_db?allowPublicKeyRetrieval=true
      username: test
      password: test_pass
      driverClassName: com.mysql.cj.jdbc.Driver
      ddlAuto: create-drop
    postgres:
      url: jdbc:postgresql:postgre_test
      username: postgre_test
      password: postgre_test
      driverClassName: org.postgresql.Driver
      ddlAuto: create-drop
    oracle:
      url: jdbc:oracle:thin:@//localhost:1521/xe
      username: system
      password: oracle
      driverClassName: oracle.jdbc.OracleDriver
      ddlAuto: update

Configuration Classes

We've created configuration classes for each data source - MysqlConfig, PostgreConfig, and OracleConfig:

package com.henry.configuration;

import com.henry.record.OracleRecord;
import com.henry.record.PostgreRecord;
import com.henry.record.MysqlRecord;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

import lombok.Data;

@Component
@ConfigurationProperties("spring.datasource")
@Data
public class DataSourceProperties {
   private MysqlRecord mysql;
   private PostgreRecord postgres;
   private OracleRecord oracle;

}

package com.henry.configuration;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.JpaVendorAdapter;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.PlatformTransactionManager;

import javax.naming.NamingException;
import javax.sql.DataSource;
import java.util.Properties;

@Configuration
@EnableJpaRepositories(
        basePackages = "com.henry.repository.user",
        entityManagerFactoryRef = "userEntityManager",
        transactionManagerRef = "userTransactionManager"
)
public class MysqlConfig {

    @Autowired
    private DataSourceProperties dsProperties;

    @Bean
    @Primary
    public LocalContainerEntityManagerFactoryBean userEntityManager()
            throws NamingException {
        LocalContainerEntityManagerFactoryBean em
                = new LocalContainerEntityManagerFactoryBean();
        em.setDataSource(userDataSource());
        em.setPackagesToScan("com.henry.model.user");

        JpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        em.setJpaVendorAdapter(vendorAdapter);
        em.setJpaProperties(userHibernateProperties());

        return em;
    }

    @Bean
    @Primary
    public DataSource userDataSource() throws IllegalArgumentException, NamingException {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName(dsProperties.getMysql().driverClassName());
        dataSource.setUrl(dsProperties.getMysql().url());
        dataSource.setUsername(dsProperties.getMysql().username());
        dataSource.setPassword(dsProperties.getMysql().password());

        return dataSource;
    }

    private Properties userHibernateProperties() {
        Properties properties = new Properties();
        properties.put("hibernate.hbm2ddl.auto",dsProperties.getMysql().ddlAuto());

        return properties;
    }

    @Primary
    @Bean
    public PlatformTransactionManager userTransactionManager() throws NamingException {
        final JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(userEntityManager().getObject());
        return transactionManager;
    }
}

package com.henry.configuration;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.JpaVendorAdapter;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.PlatformTransactionManager;

import javax.naming.NamingException;
import javax.sql.DataSource;
import java.util.Properties;

@Configuration
@EnableJpaRepositories(
        basePackages = "com.henry.repository.brand",
        entityManagerFactoryRef = "brandEntityManager",
        transactionManagerRef = "brandTransactionManager"
)
public class OracleConfig {

    @Autowired
    private DataSourceProperties dsProperties;

    @Bean
    public LocalContainerEntityManagerFactoryBean brandEntityManager()
            throws NamingException {
        LocalContainerEntityManagerFactoryBean em
                = new LocalContainerEntityManagerFactoryBean();
        em.setDataSource(brandDataSource());
        em.setPackagesToScan("com.henry.model.brand");

        JpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        em.setJpaVendorAdapter(vendorAdapter);
        em.setJpaProperties(brandHibernateProperties());

        return em;
    }

    @Bean
    public DataSource brandDataSource() throws IllegalArgumentException, NamingException {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName(dsProperties.getOracle().driverClassName());
        dataSource.setUrl(dsProperties.getOracle().url());
        dataSource.setUsername(dsProperties.getOracle().username());
        dataSource.setPassword(dsProperties.getOracle().password());

        return dataSource;
    }

    private Properties brandHibernateProperties() {
        Properties properties = new Properties();
        properties.put("hibernate.hbm2ddl.auto", dsProperties.getOracle().ddlAuto());

        return properties;
    }


    @Bean
    public PlatformTransactionManager brandTransactionManager() throws NamingException {
        final JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(brandEntityManager().getObject());
        return transactionManager;
    }
}

package com.henry.configuration;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.jdbc.datasource.DriverManagerDataSource;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.JpaVendorAdapter;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.PlatformTransactionManager;

import javax.naming.NamingException;
import javax.sql.DataSource;
import java.util.Properties;

@Configuration
@EnableJpaRepositories(
        basePackages = "com.henry.repository.company",
        entityManagerFactoryRef = "companyEntityManager",
        transactionManagerRef = "companyTransactionManager"
)
public class PostgreConfig {

    @Autowired
    private DataSourceProperties dsProperties;

    @Bean
    public LocalContainerEntityManagerFactoryBean companyEntityManager()
            throws NamingException {
        LocalContainerEntityManagerFactoryBean em
                = new LocalContainerEntityManagerFactoryBean();
        em.setDataSource(companyDataSource());
        em.setPackagesToScan("com.henry.model.company");

        JpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        em.setJpaVendorAdapter(vendorAdapter);
        em.setJpaProperties(companyHibernateProperties());

        return em;
    }

    @Bean
    public DataSource companyDataSource() throws IllegalArgumentException, NamingException {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName(dsProperties.getPostgres().driverClassName());
        dataSource.setUrl(dsProperties.getPostgres().url());
        dataSource.setUsername(dsProperties.getPostgres().username());
        dataSource.setPassword(dsProperties.getPostgres().password());

        return dataSource;
    }

    private Properties companyHibernateProperties() {
        Properties properties = new Properties();
        properties.put("hibernate.hbm2ddl.auto", dsProperties.getPostgres().ddlAuto());

        return properties;
    }

    @Bean
    public PlatformTransactionManager companyTransactionManager() throws NamingException {
        final JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(companyEntityManager().getObject());
        return transactionManager;
    }
}

Record Classes

To encapsulate the configuration properties for each data source, we've defined record classes - MysqlRecord, PostgreRecord, and OracleRecord:

package com.henry.record;

public record MysqlRecord(String url, String username, String password, String driverClassName,String ddlAuto) {
}

package com.henry.record;

public record OracleRecord(String url, String username, String password, String driverClassName,String ddlAuto) {
}

package com.henry.record;

public record PostgreRecord(String url, String username, String password, String driverClassName,String ddlAuto) {
}

Repositories

Repository interfaces extend the CrudRepository for each entity (Brand, Company, User):

package com.henry.repository.brand;

import com.henry.model.brand.Brand;
import org.springframework.data.repository.CrudRepository;

public interface BrandRepository extends CrudRepository<Brand,Long> {
}

package com.henry.repository.company;

import com.henry.model.company.Company;
import org.springframework.data.repository.CrudRepository;

public interface CompanyRepository extends CrudRepository<Company,Long> {
}

package com.henry.repository.user;

import com.henry.model.user.User;
import org.springframework.data.repository.CrudRepository;

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

Services

Service classes (BrandServiceImpl, CompanyServiceImpl, UserServiceImpl) implement a common interface (DefaultService) for generic CRUD operations:

package com.henry.service;

public sealed interface DefaultService<T, G> permits UserServiceImpl, CompanyServiceImpl, BrandServiceImpl {

    T save(T obj);
    Iterable<T>  findAll();
    T findById(G id);
}

package com.henry.service;

import com.henry.model.brand.Brand;
import com.henry.repository.brand.BrandRepository;
import org.springframework.stereotype.Service;

@Service
public final class BrandServiceImpl implements DefaultService<Brand, Long> {

    private final BrandRepository brandRepository;

    public BrandServiceImpl(BrandRepository brandRepository) {
        this.brandRepository = brandRepository;
    }


    @Override
    public Brand save(Brand obj) {
        return brandRepository.save(obj);
    }

    @Override
    public Iterable<Brand> findAll() {
        return brandRepository.findAll();
    }

    @Override
    public Brand findById(Long id) {
        return brandRepository.findById(id).get();
    }
}

package com.henry.service;

import com.henry.model.company.Company;
import com.henry.repository.company.CompanyRepository;
import org.springframework.stereotype.Service;

@Service
public final class CompanyServiceImpl implements DefaultService<Company, Long> {

    private final CompanyRepository companyRepository;

    public CompanyServiceImpl(CompanyRepository companyRepository) {
        this.companyRepository = companyRepository;
    }

    @Override
    public Company save(Company obj) {
        return companyRepository.save(obj);
    }

    @Override
    public Iterable<Company> findAll() {
        return companyRepository.findAll();
    }

    @Override
    public Company findById(Long id) {
        return companyRepository.findById(id).get();
    }
}

package com.henry.service;

import com.henry.model.user.User;
import com.henry.repository.user.UserRepository;
import org.springframework.stereotype.Service;

@Service
public final class UserServiceImpl implements DefaultService<User,Long> {

    private final UserRepository userRepository;

    public UserServiceImpl(UserRepository userRepository) {
        this.userRepository = userRepository;
    }

    @Override
    public User save(User obj) {
        return userRepository.save(obj);
    }

    @Override
    public Iterable<User> findAll() {
        return userRepository.findAll();
    }

    @Override
    public User findById(Long id) {
        return userRepository.findById(id).get();
    }
}

REST Controllers

REST controllers (BrandController, CompanyController, UserController) handle HTTP requests for creating entities:

package com.henry.controller;

import com.henry.model.brand.Brand;
import com.henry.service.DefaultService;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/api/v3")
public class BrandController {

    private final DefaultService<Brand, Long> defaultService;

    public BrandController(DefaultService<Brand, Long> defaultService) {
        this.defaultService = defaultService;
    }

    @PostMapping("/brands")
    public Brand createEmployee(@RequestBody Brand brand) {
        return defaultService.save(brand);
    }

}

package com.henry.controller;

import com.henry.model.company.Company;
import com.henry.service.DefaultService;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/api/v2")
public class CompanyController {

    private final DefaultService<Company,Long> defaultService;

    public CompanyController(DefaultService<Company, Long> defaultService) {
        this.defaultService = defaultService;
    }

    @PostMapping("/companies")
    public Company createEmployee(@RequestBody Company company) {
        return defaultService.save(company);
    }
}

package com.henry.controller;

import com.henry.model.user.User;
import com.henry.service.DefaultService;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/api/v1")
public class UserController {

    private final DefaultService<User,Long> defaultService;

    public UserController(DefaultService<User, Long> defaultService) {
        this.defaultService = defaultService;
    }

    @PostMapping("/users")
    public User createEmployee(@RequestBody User user) {
        return defaultService.save(user);
    }
}

Test Classes

JUnit test classes (BrandServiceTest, CompanyServiceTest, UserServiceTest) use Mockito for mocking dependencies:

package com.henry;

import com.google.common.collect.Iterables;
import com.henry.model.brand.Brand;
import com.henry.repository.brand.BrandRepository;
import com.henry.service.BrandServiceImpl;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.ExtendWith;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.junit.jupiter.MockitoExtension;

import java.util.Arrays;
import java.util.Optional;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.mockito.ArgumentMatchers.any;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.when;

@ExtendWith(MockitoExtension.class)
class BrandServiceTest {

    @Mock
    private BrandRepository brandRepository;

    @InjectMocks
    private BrandServiceImpl brandService;

    @Test
    void testSaveBrand() {
        Brand brand = Brand.builder()
                .id(1L)
                .name("Test Brand")
                .build();

        when(brandRepository.save(any())).thenReturn(brand);

        Brand saved = brandService.save(brand);

        assertEquals(brand, saved);
        verify(brandRepository).save(any());
    }

    @Test
    void testFindAllBrands() {
        Brand brand1 = Brand.builder()
                .id(1L)
                .name("Test Brand")
                .build();
        Brand brand2 = Brand.builder()
                .id(2L)
                .name("Demo Brand")
                .build();

        when(brandRepository.findAll()).thenReturn(Arrays.asList(brand1, brand2));

        Iterable<Brand> result = brandService.findAll();

        assertEquals(2, Iterables.size(result));
        verify(brandRepository).findAll();
    }

    @Test
    void testFindBrandById() {
        Brand brand = Brand.builder()
                .id(1L)
                .name("Demo Brand")
                .build();

        when(brandRepository.findById(1L)).thenReturn(Optional.of(brand));

        Brand result = brandService.findById(1L);

        assertEquals(brand, result);
        verify(brandRepository).findById(1L);
    }
}

package com.henry;

import com.google.common.collect.Iterables;
import com.henry.model.company.Company;
import com.henry.repository.company.CompanyRepository;
import com.henry.service.CompanyServiceImpl;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.ExtendWith;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.junit.jupiter.MockitoExtension;

import java.util.Arrays;
import java.util.Optional;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.mockito.ArgumentMatchers.any;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.when;

@ExtendWith(MockitoExtension.class)
class CompanyServiceTest {

    @Mock
    private CompanyRepository companyRepository;

    @InjectMocks
    private CompanyServiceImpl companyService;

    @Test
    void testSaveCompany() {
        Company company =
                Company.builder()
                        .id(1L)
                        .name("Test Corp")
                        .build();

        when(companyRepository.save(any())).thenReturn(company);

        Company saved = companyService.save(company);

        assertEquals(company, saved);
        verify(companyRepository).save(any());
    }

    @Test
    void testFindAllCompanies() {
        Company comp1 = Company.builder()
                .id(1L)
                .name("Test Corp")
                .build();
        Company comp2 = Company.builder()
                .id(2L)
                .name("Demo Corp")
                .build();

        when(companyRepository.findAll()).thenReturn(Arrays.asList(comp1, comp2));

        Iterable<Company> result = companyService.findAll();


        assertEquals(2, Iterables.size(result));
        verify(companyRepository).findAll();
    }

    @Test
    void testFindCompanyById() {
        Company company = Company.builder()
                .id(1L)
                .name("Test Corp")
                .build();

        when(companyRepository.findById(1L)).thenReturn(Optional.of(company));

        Company result = companyService.findById(1L);

        assertEquals(company, result);
        verify(companyRepository).findById(1L);
    }
}

package com.henry;

import com.google.common.collect.Iterables;
import com.henry.model.user.User;
import com.henry.repository.user.UserRepository;
import com.henry.service.UserServiceImpl;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.ExtendWith;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.junit.jupiter.MockitoExtension;

import java.util.Arrays;
import java.util.Optional;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.mockito.ArgumentMatchers.any;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.when;

@ExtendWith(MockitoExtension.class)
public class UserServiceTest {

    @Mock
    private UserRepository userRepository;

    @InjectMocks
    private UserServiceImpl userService;

    @Test
    public void saveUser_shouldPersistUser() {
/**

 int x = 10;
 int y = 20;
 String result = STR."\{x} + \{y} = \{x + y}";
 string templates are a preview feature and are disabled by default.
 Are string templates supported yet? - IntelliJ support - JetBrains
 https://intellij-support.jetbrains.com/hc/en-us/community/posts/13451540436114-Are-string-templates-supported-yet-
 **/

        // Create a User
        User user = User.builder()
                .id(1L)
                .name("John")
                .lastName("Doe")
                .build();

        when(userRepository.save(any())).thenReturn(user);

        User saved = userService.save(user);

        assertEquals(user, saved);
        verify(userRepository).save(any());
    }

    @Test
    void testFindAllUsers() {
        User user1 = User.builder()
                .id(1L)
                .name("John")
                .lastName("Doe")
                .build();
        User user2 = User.builder()
                .id(2L)
                .name("John")
                .lastName("Doe")
                .build();

        when(userRepository.findAll()).thenReturn(Arrays.asList(user1, user2));

        Iterable<User> result = userService.findAll();

        assertEquals(2, Iterables.size(result));
        verify(userRepository).findAll();
    }

    @Test
    void testFindUserById() {
        User user = User.builder()
                .id(1L)
                .name("John")
                .lastName("Doe")
                .build();

        when(userRepository.findById(1L)).thenReturn(Optional.of(user));

        User result = userService.findById(1L);

        assertEquals(user, result);
        verify(userRepository).findById(1L);
    }
}

Maven Configuration

The pom.xml file manages project dependencies and build configuration:

<?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>3.2.0</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.henry</groupId>
	<artifactId>multiple-data-sources-jpa</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>multiple-data-sources-jpa</name>
	<description>Demo project multiple data sources jpa</description>
	<properties>
		<java.version>21</java.version>
	</properties>
	<dependencies>

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
			<exclusions>
				<!-- Exclude the Tomcat dependency -->
				<exclusion>
					<groupId>org.springframework.boot</groupId>
					<artifactId>spring-boot-starter-tomcat</artifactId>
				</exclusion>
			</exclusions>
		</dependency>
		<!-- Use Jetty instead -->
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-jetty</artifactId>
		</dependency>

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

		<!-- MARIADB Connector -->

		<dependency>
			<groupId>org.mariadb.jdbc</groupId>
			<artifactId>mariadb-java-client</artifactId>
		</dependency>

		<!-- Mysql Connector -->
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>8.0.30</version>
		</dependency>

		<!-- ORACLE database driver -->
		<!-- https://mvnrepository.com/artifact/oracle/ojdbc6 -->
		<dependency>
			<groupId>com.oracle</groupId>
			<artifactId>ojdbc6</artifactId>
			<version>11.2.0.4</version>
		</dependency>

		<!-- POSTGRESQL database driver -->
		<dependency>
			<groupId>org.postgresql</groupId>
			<artifactId>postgresql</artifactId>
			<scope>runtime</scope>
		</dependency>

		<dependency>
			<groupId>com.google.guava</groupId>
			<artifactId>guava</artifactId>
			<version>31.0.1-jre</version>
		</dependency>

		<!-- https://mvnrepository.com/artifact/org.antlr/stringtemplate
		<dependency>
			<groupId>org.antlr</groupId>
			<artifactId>stringtemplate</artifactId>
			<version>4.0.2</version>
		</dependency>
		-->

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
		</dependency>
		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
		</dependency>
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</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-compiler-plugin</artifactId>
				<configuration>
					<source>21</source>
					<target>21</target>
					<compilerArgs>--enable-preview</compilerArgs>
				</configuration>
			</plugin>
		</plugins>
	</build>

</project>

Environment Setup with Docker Compose

To simplify the setup of your application's environment, you can use Docker Compose. Below is a docker-compose-multiple-db.yml file that defines services for Oracle, PostgreSQL, and MySQL databases:

version: '3'
services:
  oracle:
    image: pengbai/docker-oracle-xe-11g-r2
    ports:
      - "1521:1521"
      - "8080:8080"
    shm_size: 1g

  postgres:
    image: postgres:14.1
    container_name: postgre_test
    environment:
      POSTGRES_USER: postgre_test
      POSTGRES_PASSWORD: postgre_test
      POSTGRES_DB: postgre_test
    ports:
      - "5432:5432"

  mysql:
    image: mysql/mysql-server:latest
    container_name: mysql-docker-container
    environment:
      MYSQL_ROOT_PASSWORD: mypass
      MYSQL_DATABASE: test_db
      MYSQL_USER: test
      MYSQL_PASSWORD: test_pass
    ports:
      - "3306:3306"

Run command:

docker-compose -f docker-compose-multiple-db.yml up -d

Only for oracle:

mvn install:install-file "-Dfile=path/to/your/ojdbc6.jar" "-DgroupId=com.oracle" "-DartifactId=ojdbc6" "-Dversion=11.2.0.4" "-Dpackaging=jar" "-DgeneratePom=true"

Run & Test

Run Spring Boot application with command: by console, IntelliJ etc.

mvn test -Dtest=UserServiceTest

mvn test -Dtest=BrandServiceTest

mvn test -Dtest=CompanyServiceTest

Run locally: mvn spring-boot:run

POST

http://localhost:9000/api/v1/users

{
    "name": "henry",
    "lastName": "x"
}

POST

http://localhost:9000/api/v2/companies

{
    "name": "company1"
}

POST

http://localhost:9000/api/v3/brands

{
    "name": "Demo Brand"
}

Source Code

Here on GitHub.

Notes:

Possible issues:

Lombok Plugin check if it was installed in IntelliJ
Others issues please -> File | Invalidate Caches
Change the port if you have in local databases. Otherwise you have conflicts.

TechNotes Central

Tuesday, December 19, 2023

Multiple Data Sources in Spring Boot 3 with Java 21

Technology

Project Structure

Application.yaml Configuration

Configuration Classes

Record Classes

package com.henry.record; public record PostgreRecord(String url, String username, String password, String driverClassName,String ddlAuto) { }

Repositories

package com.henry.repository.user; import com.henry.model.user.User; import org.springframework.data.repository.CrudRepository; public interface UserRepository extends CrudRepository<User,Long> { }

Services

REST Controllers

Test Classes

Maven Configuration

Environment Setup with Docker Compose

Run & Test

Source Code

Notes:

Virtual Threads in Java 21: Simplified Concurrency for Modern Applications