一、主流的多数据源支持方式

1. 将数据源对象作为参数，传递到调用方法内部，这种方式增加额外的编码。
2. 将Repository操作接口分包存放，Spring扫描不同的包，自动注入不同的数据源。这种方式实现简单，也是一种“约定大于配置”思想的典型应用。本文将以这种方式实现JPA的多数据源支持
3. 使用Spring AOP面向切面编程，然后在持久层接口方法上面加注解，不同的注解使用表示使用不同的数据源。在此暂不做介绍。

二、修改application.yml配置多数据源

spring:datasource:primary:jdbc-url: jdbc:mysql://localhost:3306/testdb?useUnicode=true&characterEncoding=utf-8username: rootpassword: 123456driver-class-name: com.mysql.jdbc.Driversecondary:jdbc-url: jdbc:mysql://localhost:3306/testdb?useUnicode=true&characterEncoding=utf-8username: rootpassword: 123456driver-class-name: com.mysql.jdbc.Driverjpa:hibernate:ddl-auto: updatedatabase: mysqlshow-sql: true

三、 两组数据持久化接口及实体类,放到不同的package里面

1. 将4.6章节中使用到的Article.java及ArticleRepository.java放到club.krislin.bootlaunch.jpa.testdb下面
2. 然后写另外一套操作接口放到club.krislin.bootlaunch.jpa.testdb2下面，如下：

@Data
@Entity
public class Message {@Id@GeneratedValueprivate Long id;@Column(nullable = false)private String name;@Column(nullable = false)private String content;}
public interface MessageRepository extends JpaRepository<Message,Long> {}

四、多数据源支持

数据源DataSource的Bean对象创建并注入Spring上下文，分别对应application.yml里面的两套数据源配置

@Configuration
public class JPADataSourceConfig {@Primary@Bean(name = "primaryDataSource")@Qualifier("primaryDataSource")@ConfigurationProperties(prefix="spring.datasource.primary")    //结合application.yml的配置public DataSource primaryDataSource() {return DataSourceBuilder.create().build();}@Bean(name = "secondaryDataSource")@Qualifier("secondaryDataSource")@ConfigurationProperties(prefix="spring.datasource.secondary")   //结合application.yml的配置public DataSource secondaryDataSource() {return DataSourceBuilder.create().build();}
}

配置实体扫描以及事务管理,注意看@Primary和带注释的地方

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(entityManagerFactoryRef="entityManagerFactoryPrimary",transactionManagerRef="transactionManagerPrimary",basePackages= { "club.krislin.bootlaunch.jpa.testdb" }) //设置Repository所在位置
public class JPAPrimaryConfig {@Resource@Qualifier("primaryDataSource")private DataSource primaryDataSource;        //primary数据源注入@Primary@Bean(name = "entityManagerPrimary")        //primary实体管理器public EntityManager entityManager(EntityManagerFactoryBuilder builder) {return entityManagerFactoryPrimary(builder).getObject().createEntityManager();}@Primary@Bean(name = "entityManagerFactoryPrimary")    //primary实体工厂public LocalContainerEntityManagerFactoryBean entityManagerFactoryPrimary (EntityManagerFactoryBuilder builder) {return builder.dataSource(primaryDataSource).properties(getVendorProperties()).packages("club.krislin.bootlaunch.jpa.testdb")     //设置实体类所在位置.persistenceUnit("primaryPersistenceUnit").build();}@Resourceprivate JpaProperties jpaProperties;private Map getVendorProperties() {return jpaProperties.getHibernateProperties(new HibernateSettings());}@Primary@Bean(name = "transactionManagerPrimary")         //primary事务管理器public PlatformTransactionManager transactionManagerPrimary(EntityManagerFactoryBuilder builder) {return new JpaTransactionManager(entityManagerFactoryPrimary(builder).getObject());}
}

上面的代码将扫描club.krislin.bootlaunch.jpa.testdb下面的实体对象和Repository，并使用primary数据源。仿造这段代码再写一套club.krislin.bootlaunch.jpa.testdb2的配置使用secondary数据源。代码如下：

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(entityManagerFactoryRef="entityManagerFactorySecondary",transactionManagerRef="transactionManagerSecondary",basePackages= { "club.krislin.bootlaunch.jpa.testdb2" }) //设置Repository所在位置
public class JPASecondaryConfig {@Resource@Qualifier("secondaryDataSource")private DataSource secondaryDataSource;@Bean(name = "entityManagerSecondary")public EntityManager entityManager(EntityManagerFactoryBuilder builder) {return entityManagerFactorySecondary(builder).getObject().createEntityManager();}@Bean(name = "entityManagerFactorySecondary")public LocalContainerEntityManagerFactoryBean entityManagerFactorySecondary (EntityManagerFactoryBuilder builder) {return builder.dataSource(secondaryDataSource).properties(getVendorProperties()).packages("club.krislin.bootlaunch.jpa.testdb2") //设置实体类所在位置.persistenceUnit("secondaryPersistenceUnit").build();}@Resourceprivate JpaProperties jpaProperties;private Map getVendorProperties() {return jpaProperties.getHibernateProperties(new HibernateSettings());}@Bean(name = "transactionManagerSecondary")PlatformTransactionManager transactionManagerSecondary(EntityManagerFactoryBuilder builder) {return new JpaTransactionManager(entityManagerFactorySecondary(builder).getObject());}}

五、测试

//先构造一个Article对象article，这个操作针对testdb
articleRepository.save(article);
//在构造一个Message对象message，这个操作针对testdb2
messageRepository.save(message);

如果article数据能正确插入testdb的article表，message数据能正确的插入testdb2的message表，则JPA的多数据源实现正确。