如何配置多数据源

在 application.properties 中定义两个 DataSource

定义两个 DataSource 用来读取 application.properties 中的不同配置。如下例子中，主数据源配置为 spring.datasource.one 开头的配置，第二数据源配置为 spring.datasource.two 开头的配置。

//这是默认配置，我们做一下对比
spring.datasource.url=db1
spring.datasource.username=db1_username
spring.datasource.password=db1_password
//# Druid 数据源配置，继承spring.datasource.* 配置，相同则覆盖
...
spring.datasource.druid.initial-size=5
spring.datasource.druid.max-active=5
...//#Druid 数据源 1 配置，继承spring.datasource.druid.* 配置，相同则覆盖
//#db1的配置会上面的配置
...
spring.datasource.druid.one.url=db1
spring.datasource.druid.one.username=db1_username
spring.datasource.druid.one.password=db1_password
spring.datasource.druid.one.max-active=10
spring.datasource.druid.one.max-wait=10000
...
//# Druid 数据源 2 配置，继承spring.datasource.druid.* 配置，相同则覆盖
...
spring.datasource.druid.two.url=db2
spring.datasource.druid.two.username=db2_username
spring.datasource.druid.two.password=db2_password
spring.datasource.druid.two.max-active=20
spring.datasource.druid.two.max-wait=20000
...

定义两个 DataSourceConfigJava 类

两个 DataSourceConfig 类内容如下：

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(entityManagerFactoryRef="entityManagerFactoryOne",transactionManagerRef="transactionManagerOne",basePackages= { "com.jackzhang.example.one" }) //设置Repository所在位置
@EnableConfigurationProperties(JpaProperties.class)
public class DataSourceOneConfig {/*** 配置数据源1*/@Primary@Bean(name = "dataSourceOne")@ConfigurationProperties("spring.datasource.druid.one")public DataSource dataSourceOne(){return DruidDataSourceBuilder.create().build();}@Autowired@Qualifier("dataSourceOne")private DataSource oneDataSource;@Primary@Bean(name = "entityManagerOne")public EntityManager entityManager(EntityManagerFactoryBuilder builder) {return entityManagerFactoryOne(builder).getObject().createEntityManager();}@Primary@Bean(name = "entityManagerFactoryOne")public LocalContainerEntityManagerFactoryBean entityManagerFactoryOne (EntityManagerFactoryBuilder builder) {return builder.dataSource(oneDataSource).properties(getVendorProperties(oneDataSource)).packages("com.jackzhang.example.one") //设置实体类所在位置.persistenceUnit("onePersistenceUnit").build();}@Autowiredprivate JpaProperties jpaProperties;private Map<String, String> getVendorProperties(DataSource dataSource) {return jpaProperties.getHibernateProperties(dataSource);}@Primary@Bean(name = "transactionManagerOne")public PlatformTransactionManager transactionManagerOne(EntityManagerFactoryBuilder builder) {return new JpaTransactionManager(entityManagerFactoryOne(builder).getObject());}
}
@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(entityManagerFactoryRef="entityManagerFactoryTwo",transactionManagerRef="transactionManagerTwo",basePackages= { "com.jackzhang.example.two" }) //设置Repository所在位置
@EnableConfigurationProperties(JpaProperties.class)
public class DataSourceTwoConfig {/*** 配置数据源2*/@Primary@Bean(name = "dataSourceTwo")@ConfigurationProperties("spring.datasource.druid.two")public DataSource dataSourceTwo(){return DruidDataSourceBuilder.create().build();}@Autowired@Qualifier("dataSourceTwo")private DataSource twoDataSource;@Primary@Bean(name = "entityManagerTwo")public EntityManager entityManager(EntityManagerFactoryBuilder builder) {return entityManagerFactoryTwo(builder).getObject().createEntityManager();}@Primary@Bean(name = "entityManagerFactoryTwo")public LocalContainerEntityManagerFactoryBean entityManagerFactoryTwo (EntityManagerFactoryBuilder builder) {return builder.dataSource(twoDataSource).properties(getVendorProperties(twoDataSource)).packages("com.jackzhang.example.two") //设置实体类所在位置.persistenceUnit("twoPersistenceUnit").build();}@Autowiredprivate JpaProperties jpaProperties;private Map<String, String> getVendorProperties(DataSource dataSource) {return jpaProperties.getHibernateProperties(dataSource);}@Primary@Bean(name = "transactionManagerTwo")public PlatformTransactionManager transactionManagerTwo(EntityManagerFactoryBuilder builder) {return new JpaTransactionManager(entityManagerFactoryTwo(builder).getObject());}
}

我们发现 DataSourceTwoConfig、DataSourceOneConfig 内容基本一样，思路就是管理两套 datasource，从而带来了两套 transactionManager，分别在这两个 package 下创建各自的实体和数据访问接口即可。当然了也可以通过 @Transactional(rollbackFor = Exception.class, transactionManager= "transactionManagerOne") 来手动选择哪个数据源。

多数据源的场景

随着微服务的推行，其实很少有多数据源的场景的，作者不建议出现多数据源，当出现的时候就要想想，模块划分的是否合理，是否可以通过服务去解决，但不排除 Job 等。