很多业务场景都需要使用到多数据库，本文介绍springboot对多数据源的使用。

这次先说一下application.properties文件，分别连接了2个数据库test和test1。完整代码如下：

##端口号
server.port=8888


##数据库url
spring.datasource.test.url=jdbc:mysql://localhost:3306/test?characterEncoding=utf8&useSSL=false
##数据库用户名
spring.datasource.test.username=root
##数据库密码
spring.datasource.test.password=root
##数据库驱动
spring.datasource.test.driver-class-name=com.mysql.jdbc.Driver


##数据库url
spring.datasource.test2.url=jdbc:mysql://localhost:3306/test2?characterEncoding=utf8&useSSL=false
##数据库用户名
spring.datasource.test2.username=root
##数据库密码
spring.datasource.test2.password=root
##数据库驱动
spring.datasource.test2.driver-class-name=com.mysql.jdbc.Driver


spring.jpa.hibernate.ddl-auto=create
##控制台打印sql
spring.jpa.show-sql=true

然后说一下处理多数据源的DataSourceConfig，其中@ConfigurationProperties注解对应刚才的数据库，而且这个重点是一定要有一个主数据源，并且在上面加上@Primary，代码如下：

package com.dalaoyang.config;

import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;

import javax.sql.DataSource;
/**
 * @author dalaoyang
 * @Description
 * @project springboot_learn
 * @package com.dalaoyang.config
 * @email yangyang@dalaoyang.cn
 * @date 2018/4/10
 */
@Configuration
public class DataSourceConfig {
    @Bean(name = "testDataSource")
    @Qualifier("testDataSource")
    @ConfigurationProperties(prefix="spring.datasource.test")
    public DataSource primaryDataSource() {
        return DataSourceBuilder.create().build();
    }

    @Bean(name = "test2DataSource")
    @Qualifier("test2DataSource")
    @Primary
    @ConfigurationProperties(prefix="spring.datasource.test2")
    public DataSource secondaryDataSource() {
        return DataSourceBuilder.create().build();
    }
}

接下来是对应test数据库的配置，其中需要说一下的是@EnableJpaRepositories注解里面的basePackages属性对应的是这个数据源对应的repository（因为本文使用的是jpa）， @Qualifier注解内的value要和DataSourceConfig的值一致即可。
代码如下：

package com.dalaoyang.config;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.orm.jpa.JpaProperties;
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.EntityManager;
import javax.sql.DataSource;
import java.util.Map;

/**
 * @author dalaoyang
 * @Description
 * @project springboot_learn
 * @package com.dalaoyang.config
 * @email yangyang@dalaoyang.cn
 * @date 2018/4/10
 */
@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
        entityManagerFactoryRef="entityManagerFactoryPrimary",
        transactionManagerRef="transactionManagerPrimary",
        basePackages= { "com.dalaoyang.repository.datasource" })
public class TestDataSourceConfig {
    @Autowired
    @Qualifier("testDataSource")
    private DataSource dataSource;

    @Primary
    @Bean(name = "entityManagerPrimary")
    public EntityManager entityManager(EntityManagerFactoryBuilder builder) {
        return entityManagerFactoryPrimary(builder).getObject().createEntityManager();
    }

    @Primary
    @Bean(name = "entityManagerFactoryPrimary")
    public LocalContainerEntityManagerFactoryBean entityManagerFactoryPrimary (EntityManagerFactoryBuilder builder) {
        return builder
                .dataSource(dataSource)
                .properties(getVendorProperties(dataSource))
                .packages("com.dalaoyang.entity.datasource") //设置实体类所在位置
                .persistenceUnit("primaryPersistenceUnit")
                .build();
    }

    @Autowired
    private JpaProperties jpaProperties;

    private Map<String, String> getVendorProperties(DataSource dataSource) {
        return jpaProperties.getHibernateProperties(dataSource);
    }

    @Primary
    @Bean(name = "transactionManagerPrimary")
    public PlatformTransactionManager transactionManagerPrimary(EntityManagerFactoryBuilder builder) {
        return new JpaTransactionManager(entityManagerFactoryPrimary(builder).getObject());
    }
}

Test2DataSourceConfig就不多说了，和TestDataSourceConfig原理一致，代码如下：

package com.dalaoyang.config;


import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.orm.jpa.JpaProperties;
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.EntityManager;
import javax.sql.DataSource;
import java.util.Map;
/**
 * @author dalaoyang
 * @Description
 * @project springboot_learn
 * @package com.dalaoyang.config
 * @email yangyang@dalaoyang.cn
 * @date 2018/4/10
 */
@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
        entityManagerFactoryRef="entityManagerFactorySecondary",
        transactionManagerRef="transactionManagerSecondary",
        basePackages= { "com.dalaoyang.repository.datasource2" }) //设置Repository所在位置
public class Test2DataSourceConfig {
    @Autowired
    @Qualifier("test2DataSource")
    private DataSource dataSource;

    @Bean(name = "entityManagerSecondary")
    public EntityManager entityManager(EntityManagerFactoryBuilder builder) {
        return entityManagerFactorySecondary(builder).getObject().createEntityManager();
    }

    @Bean(name = "entityManagerFactorySecondary")
    public LocalContainerEntityManagerFactoryBean entityManagerFactorySecondary (EntityManagerFactoryBuilder builder) {
        return builder
                .dataSource(dataSource)
                .properties(getVendorProperties(dataSource))
                .packages("com.dalaoyang.entity.datasource2") //设置实体类所在位置
                .persistenceUnit("secondaryPersistenceUnit")
                .build();
    }

    @Autowired
    private JpaProperties jpaProperties;

    private Map<String, String> getVendorProperties(DataSource dataSource) {
        return jpaProperties.getHibernateProperties(dataSource);
    }

    @Bean(name = "transactionManagerSecondary")
    PlatformTransactionManager transactionManagerSecondary(EntityManagerFactoryBuilder builder) {
        return new JpaTransactionManager(entityManagerFactorySecondary(builder).getObject());
    }
}

下面是对应的model和repository

City类

package com.dalaoyang.entity.datasource;

import javax.persistence.*;

/**
 * @author dalaoyang
 * @Description
 * @project springboot_learn
 * @package com.dalaoyang.Entity
 * @email 397600342@qq.com
 * @date 2018/4/7
 */
@Entity
@Table(name="city")
public class City {

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int cityId;
    private String cityName;
    private String cityIntroduce;

    public City(int cityId, String cityName, String cityIntroduce) {
        this.cityId = cityId;
        this.cityName = cityName;
        this.cityIntroduce = cityIntroduce;
    }

    public City(String cityName, String cityIntroduce) {
        this.cityName = cityName;
        this.cityIntroduce = cityIntroduce;
    }

    public City() {
    }

    public int getCityId() {
        return cityId;
    }

    public void setCityId(int cityId) {
        this.cityId = cityId;
    }

    public String getCityName() {
        return cityName;
    }

    public void setCityName(String cityName) {
        this.cityName = cityName;
    }

    public String getCityIntroduce() {
        return cityIntroduce;
    }

    public void setCityIntroduce(String cityIntroduce) {
        this.cityIntroduce = cityIntroduce;
    }


}

House类

package com.dalaoyang.entity.datasource2;

import javax.persistence.*;

/**
 * @author dalaoyang
 * @Description
 * @project springboot_learn
 * @package com.dalaoyang.entity
 * @email yangyang@dalaoyang.cn
 * @date 2018/4/10
 */
@Entity
@Table(name="house")
public class House {

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int houseId;
    private String houseName;
    private String houseIntroduce;

    public int getHouseId() {
        return houseId;
    }

    public void setHouseId(int houseId) {
        this.houseId = houseId;
    }

    public String getHouseName() {
        return houseName;
    }

    public void setHouseName(String houseName) {
        this.houseName = houseName;
    }

    public String getHouseIntroduce() {
        return houseIntroduce;
    }

    public void setHouseIntroduce(String houseIntroduce) {
        this.houseIntroduce = houseIntroduce;
    }

    public House(String houseName, String houseIntroduce) {
        this.houseName = houseName;
        this.houseIntroduce = houseIntroduce;
    }
}

CityRepository

package com.dalaoyang.repository.datasource;

import com.dalaoyang.entity.datasource.City;
import org.springframework.data.jpa.repository.JpaRepository;

/**
 * @author dalaoyang
 * @Description
 * @project springboot_learn
 * @package com.dalaoyang.Repository
 * @email 397600342@qq.com
 * @date 2018/4/7
 */
public interface CityRepository extends JpaRepository<City,Integer> {
}

HouseRepository

package com.dalaoyang.repository.datasource2;

import com.dalaoyang.entity.datasource2.House;
import org.springframework.data.jpa.repository.JpaRepository;

/**
 * @author dalaoyang
 * @Description
 * @project springboot_learn
 * @package com.dalaoyang.repository.datasource2
 * @email yangyang@dalaoyang.cn
 * @date 2018/4/10
 */
public interface HouseRepository extends JpaRepository<House,Integer> {
}

pom文件

<?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>

	<groupId>com.dalaoyang</groupId>
	<artifactId>springboot_datasources</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>springboot_datasources</name>
	<description>springboot_datasources</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>1.5.9.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
		<java.version>1.8</java.version>
	</properties>

	<dependencies>
		<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>
		<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>
		</plugins>
	</build>


</project>

因为上面这些都没什么可说的，都是和正常的写法没什么区别，最后是TestController测试类

package com.dalaoyang.controller;

import com.dalaoyang.entity.datasource.City;
import com.dalaoyang.entity.datasource2.House;
import com.dalaoyang.repository.datasource.CityRepository;
import com.dalaoyang.repository.datasource2.HouseRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * @author dalaoyang
 * @Description
 * @project springboot_learn
 * @package com.dalaoyang.controller
 * @email yangyang@dalaoyang.cn
 * @date 2018/4/10
 */
@RestController
public class TestController {

    @Autowired
    CityRepository cityRepository;

    @Autowired
    HouseRepository houseRepository;

    @GetMapping("/testDataSource")
    public String testDataSource(){
        City city = new City("北京","中国首都");
        cityRepository.save(city);
        return "success";
    }

    @GetMapping("/testDataSource2")
    public String testDataSource2(){
        House house = new House("豪宅","特别大的豪宅");
        houseRepository.save(house);
        return "success";
    }

}

启动项目可以看到test数据库中新建了city表，test2数据库中新建了house表。