Spring Boot 整合 JPA 使用多个数据源

介绍

JPA（Java Persistence API）Java 持久化 API，是 Java 持久化的标准规范，Hibernate 是持久化规范的技术实现，而 Spring Data JPA 是在 Hibernate 基础上封装的一款框架。
第一次使用 Spring JPA 的时候，感觉这东西简直就是神器，几乎不需要写什么关于数据库访问的代码一个基本的 CURD 的功能就出来了。在这篇文章中，我们将介绍 Spring Boot 整合 JPA 使用多个数据源的方法。
开发环境：

• Spring Boot 2.0.5
• Spring Data JPA 2.0.5
• MySQL 5.6
• JDK 8
• IDEA 2018.3
• Windows 10

引入依赖

首先我们要 Spring Boot 引入 spring-boot-starter-data-jpa 依赖。

Maven 配置：

   <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>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <scope>runtime</scope>
    </dependency>

Gradle 配置：

compile group: 'org.springframework.boot', name: 'spring-boot-starter-data-jpa', version: '2.0.5.RELEASE'
compile group: 'org.springframework.boot', name: 'spring-boot-starter-web', version: '2.0.5.RELEASE'
compile group: 'org.springframework.boot', name: 'spring-boot-devtools', version: '2.0.5.RELEASE'
compile group: 'mysql', name: 'mysql-connector-java', version: '6.0.6'

配置数据源

Spring Boot 提供了使用 application.properties 或 application.yml 文件配置项目属性的方法。我比较习惯使用 application.yml 文件，所以这里我只列出 application.yml 文件的写法。

spring:
  datasource:
    product:
      driver-class-name: com.mysql.jdbc.Driver
      jdbc-url: jdbc:mysql://127.0.0.1:3306/product?useUnicode=true&characterEncoding=utf-8&serverTimezone=UTC&autoReconnect=true&useSSL=false&zeroDateTimeBehavior=convertToNull
      username: root
      password: test123$
    customer:
      driver-class-name: com.mysql.jdbc.Driver
      jdbc-url: jdbc:mysql://127.0.0.1:3306/customer?useUnicode=true&characterEncoding=utf-8&serverTimezone=UTC&autoReconnect=true&useSSL=false&zeroDateTimeBehavior=convertToNull
      username: root
      password: test123$
  jpa:
    generate-ddl: true

配置好 application.yml 文件后分别在数据库创建 customer 和 product 数据库。

添加实体（Entity）类

客户实体：

package com.springboot.jpa.customer.models;

import javax.persistence.*;

@Entity
public class Customer {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;
    @Column(unique = true, nullable = false)
    private String email;
    private String firstName;
    private String lastName;

    protected Customer() {
    }

    public Customer(String email, String firstName, String lastName) {
        this.email = email;
        this.firstName = firstName;
        this.lastName = lastName;
    }

    @Override
    public String toString() {
        return String.format("Customer[id=%d, firstName='%s', lastName='%s',email='%s']", id, firstName, lastName, email);
    }

    public Integer getId() {
        return id;
    }

    public String getEmail() {
        return email;
    }

    public String getFirstName() {
        return firstName;
    }

    public String getLastName() {
        return lastName;
    }
}

产品实体：

package com.springboot.jpa.product.models;

import javax.persistence.*;

@Entity
public class Product {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int id;

    @Column(nullable = false)
    private String code;
    private String name;
    private double price;


    protected Product() {
    }

    public Product(String code, String name, double price) {
        this.code = code;
        this.name = name;
        this.price = price;
    }

    @Override
    public String toString() {
        return String.format("Product[id=%d, code='%s', name='%s', price='%s']", id, code, name, price);
    }

    public int getId() {
        return id;
    }

    public String getCode() {
        return code;
    }

    public String getName() {
        return name;
    }

    public double getPrice() {
        return price;
    }
}

添加数据仓库（Repository）类

客户 Repository：

package com.springboot.jpa.customer.repository;

import com.springboot.jpa.customer.models.Customer;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface CustomerRepository extends JpaRepository<Customer, Integer> {
}

产品 Repository：

package com.springboot.jpa.product.repository;

import com.springboot.jpa.product.models.Product;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface ProductRepository extends JpaRepository<Product, Integer> {
}

添加配置（Config）类

客户配置：

package com.springboot.jpa.customer.config;

import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.jdbc.DataSourceBuilder;
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 = "customerEntityManagerFactory", transactionManagerRef = "customerTransactionManager", basePackages = {"com.springboot.jpa.customer.repository"})
public class CustomerConfig {

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

    @Primary
    @Bean(name = "customerEntityManagerFactory")
    public LocalContainerEntityManagerFactoryBean entityManagerFactory(EntityManagerFactoryBuilder builder, @Qualifier("customerDataSource") DataSource dataSource) {
        return builder.dataSource(dataSource).packages("com.springboot.jpa.customer.models").persistenceUnit("customer").build();
    }

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

产品配置：

package com.springboot.jpa.product.config;


import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.jdbc.DataSourceBuilder;
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 = "productEntityManagerFactory", transactionManagerRef = "productTransactionManager", basePackages = {"com.springboot.jpa.product.repository"}
)
public class ProductConfig {

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

    @Bean(name = "productEntityManagerFactory")
    public LocalContainerEntityManagerFactoryBean barEntityManagerFactory(EntityManagerFactoryBuilder builder, @Qualifier("productDataSource") DataSource dataSource) {
        return builder.dataSource(dataSource).packages("com.springboot.jpa.product.models").persistenceUnit("product").build();
    }

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

项目结构：

src/main/java
- com.springboot.jpa
      - product
        - config
        - models
        - repository
      - customer
        - config
        - models
        - repository

添加测试类

客户测试类 CustomerDataSourcesTests：

package com.springboot.jpa;

import com.springboot.jpa.customer.repository.CustomerRepository;
import com.springboot.jpa.customer.models.Customer;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.transaction.annotation.Transactional;

import org.junit.Test;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertNotNull;

@RunWith(SpringRunner.class)
@SpringBootTest
public class CustomerDataSourcesTests {

    @Autowired
    private CustomerRepository customerRepository;

    @Test
    @Transactional("customerTransactionManager")
    public void createCustomer() {

        Customer customer = new Customer("master@weilog.net", "Charles", "Zhang");
        customer = customerRepository.save(customer);
        assertNotNull(customerRepository.findById(customer.getId()));
        assertEquals(customerRepository.findById(customer.getId()).get().getEmail(), "master@weilog.net");
    }
}

产品测试类 ProductDataSourcesTests：

package com.springboot.jpa;

import com.springboot.jpa.product.models.Product;
import com.springboot.jpa.product.repository.ProductRepository;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.transaction.annotation.Transactional;

import org.junit.Test;

import static org.junit.Assert.assertNotNull;

@RunWith(SpringRunner.class)
@SpringBootTest
public class ProductDataSourcesTests {

    @Autowired
    private ProductRepository productRepository;

    @Test
    @Transactional("productTransactionManager")
    public void createProduct() {
        Product product = new Product("10000", "Book", 80.0);
        product = productRepository.save(product);

        assertNotNull(productRepository.findById(product.getId()));
    }

}

测试

分别运行两个测试类通过后，查询数据库。
客户表：

mysql> SELECT * FROM customer;
+----+-------------------+-----------+----------+
| id | email             | firstName | lastName |
+----+-------------------+-----------+----------+
|  1 | master@weilog.net | Charles   | Zhang    |
+----+-------------------+-----------+----------+
1 row in set

产品表：

mysql> SELECT * FROM product;
+----+-------+------+-------+
| id | code  | name | price |
+----+-------+------+-------+
|  1 | 10000 | Book |    80 |
+----+-------+------+-------+
1 row in set

本文地址：Spring Boot 整合 JPA 使用多个数据源
项目地址：spring-boot-jpa