package com.example.demo.test.data;

import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "test")
public class Test {

  @Id
  private Integer id;

  public Test(){

  }

  public Integer getId() {
    return this.id;
  }

  public void setId(Integer id){
    this.id = id;
  }
}

package com.example.demo.other.data;

import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "other")
public class Other {

  @Id
  private Integer id;

  public Integer getId() {
    return this.id;
  }

  public void setId(Integer id){
    this.id = id;
  }
}

package com.example.demo.test.data;

import org.springframework.data.jpa.repository.JpaRepository;

public interface TestRepository extends JpaRepository<Test, Integer> {
}

package com.example.demo.other.data;

import org.springframework.data.jpa.repository.JpaRepository;

public interface OtherRepository extends JpaRepository<Other, Integer> {
}

package com.example.demo.config;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;
import org.springframework.boot.autoconfigure.orm.jpa.JpaProperties;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.orm.jpa.EntityManagerFactoryBuilder;
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.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;

import javax.persistence.EntityManagerFactory;
import javax.sql.DataSource;

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
    entityManagerFactoryRef = "entityManagerFactory",
    basePackages = {"com.example.demo.test.data"}
)
public class TestDataConfig {

  @Autowired
  private JpaProperties jpaProperties;

  @Primary
  @Bean(name = "dataSource")
  @ConfigurationProperties(prefix = "spring.datasource")
  public DataSource dataSource() {
    return DataSourceBuilder.create().build();
  }

  @Primary
  @Bean(name = "entityManagerFactory")
  public LocalContainerEntityManagerFactoryBean entityManagerFactory(
      EntityManagerFactoryBuilder builder,
      @Qualifier("dataSource") DataSource dataSource) {
    return builder
        .dataSource(dataSource)
        .packages("com.example.demo.test.data")
        .properties(jpaProperties.getHibernateProperties(dataSource))
        .persistenceUnit("test")
        .build();
  }

  @Primary
  @Bean(name = "transactionManager")
  public PlatformTransactionManager transactionManager(
      @Qualifier("entityManagerFactory") EntityManagerFactory entityManagerFactory) {
    return new JpaTransactionManager(entityManagerFactory);
  }

}

package com.example.demo.config;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;
import org.springframework.boot.autoconfigure.orm.jpa.JpaProperties;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.orm.jpa.EntityManagerFactoryBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;

import javax.persistence.EntityManagerFactory;
import javax.sql.DataSource;

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
    entityManagerFactoryRef = "otherEntityManagerFactory",
    transactionManagerRef = "otherTransactionManager",
    basePackages = {"com.example.demo.other.data"}
)
public class OtherDataConfig {

  @Autowired
  private JpaProperties jpaProperties;

  @Bean(name = "otherDataSource")
  @ConfigurationProperties(prefix = "other.datasource")
  public DataSource otherDataSource() {
    return DataSourceBuilder.create().build();
  }

  @Bean(name = "otherEntityManagerFactory")
  public LocalContainerEntityManagerFactoryBean otherEntityManagerFactory(
      EntityManagerFactoryBuilder builder,
      @Qualifier("otherDataSource") DataSource otherDataSource) {
    return builder
        .dataSource(otherDataSource)
        .packages("com.example.demo.other.data")
        .properties(jpaProperties.getHibernateProperties(otherDataSource))
        .persistenceUnit("other")
        .build();
  }

  @Bean(name = "otherTransactionManager")
  public PlatformTransactionManager otherTransactionManager(
      @Qualifier("otherEntityManagerFactory") EntityManagerFactory otherEntityManagerFactory) {
    return new JpaTransactionManager(otherEntityManagerFactory);
  }

}

package com.example.demo.service;

import com.example.demo.other.data.Other;
import com.example.demo.other.data.OtherRepository;
import com.example.demo.test.data.Test;
import com.example.demo.test.data.TestRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component
public class TestService {

  @Autowired
  private TestRepository testRepository;

  @Autowired
  private OtherRepository otherRepository;

  @Value("${name:World}")
  private String name;

  public String getHelloMessage() {
    Test test = new Test();
    test.setId(1);
    test = testRepository.save(test);

    Other other = new Other();
    other.setId(2);
    other = otherRepository.save(other);

    return "Hello " + this.name + " : test's value = " + test.getId() + " , other's value = " + other.getId();

  }

}

spring:
 datasource:
  url: jdbc:mysql://localhost:3306/test?characterEncoding=utf-8&useSSL=false
  testWhileIdle: true
  validationQuery: SELECT 1 from dual
  username: test
  password: 11111111
  driverClassName: com.mysql.jdbc.Driver
 jpa:
  database: MYSQL
  show-sql: true
  hibernate:
   show-sql: true
   ddl-auto: create
   naming-strategy: org.hibernate.cfg.ImprovedNamingStrategy
  properties:
   hibernate.dialect: org.hibernate.dialect.MySQL5Dialect
other:
 datasource:
  url: jdbc:mysql://localhost:3306/other?characterEncoding=utf-8&useSSL=false
  testWhileIdle: true
  validationQuery: SELECT 1
  username: other
  password: 11111111
  driverClassName: com.mysql.jdbc.Driver
 jpa:
  database: MYSQL
  show-sql: true
  hibernate:
   show-sql: true
   ddl-auto: create
   naming-strategy: org.hibernate.cfg.ImprovedNamingStrategy
  properties:
   hibernate.dialect: org.hibernate.dialect.MySQL5Dialect

@ConfigurationProperties(prefix = "other.datasource")

CREATE USER 'test'@'localhost' IDENTIFIED BY '11111111';
GRANT ALL PRIVILEGES ON *.* TO 'test'@'localhost';
CREATE USER 'other'@'localhost' IDENTIFIED BY '11111111';
GRANT ALL PRIVILEGES ON *.* TO 'other'@'localhost';
create database test;
create database other;