利用SpringDataJPA实现多数据源动态切换

多数据源配置原因：分布式数据库读写分离、集成不同数据库等。都是为了提高项目的可维护性、稳定性、响应速度。

目录结构

application.properties配置

#-----------------数据库配置
#主
spring.datasource.url=jdbc:postgresql://localhost:1234/db1
spring.datasource.username=postgres
spring.datasource.password=admin
spring.datasource.driverClassName=org.postgresql.Driver

#从
spring.slave.datasource.url=jdbc:postgresql://localhost:4321/db2
spring.slave.datasource.username=postgres
spring.slave.datasource.password=admin
spring.slave.datasource.driverClassName=org.postgresql.Driver
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.PostgreSQLDialect

DataSourceConfig.java

自定义一个数据源配置类DataSourceConfig，在类内对应声明两个数据源的Bean对象并配置application.properties文件对应的数据库信息

@Configuration
public class DataSourceConfig {
    @Bean("primaryDataSource")
    @Qualifier("primaryDataSource")
    @Primary
    @ConfigurationProperties(prefix = "spring.datasource")
    public DataSource primaryDataSource(){
        return DataSourceBuilder.create().build();
    }

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

主数据源配置 PrimaryConfig.java

注意修改两个数据源配置文件中对应实体类所在位置

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
        entityManagerFactoryRef = "entityManagerFactoryPrimary",
        transactionManagerRef = "transactionManagerPrimary",
        basePackages = {"com.example.repository.primary"}) //设置Repository所在位置
public class PrimaryConfig {

    @Autowired
    @Qualifier("primaryDataSource")
    private DataSource primaryDataSource;

    @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(primaryDataSource)
                .properties(getVendorProperties(primaryDataSource))
                .packages("com.example.entity.primary") //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());
    }
}

第二数据源配置

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
        entityManagerFactoryRef="entityManagerFactorySecondary",
        transactionManagerRef="transactionManagerSecondary",
        basePackages= { "com.example.repository.secondary" }) //设置Repository所在位置
public class SecondaryConfig {

    @Autowired
    @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(secondaryDataSource))
                .packages("com.example.entity.secondary") //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());
    }
}

编写实体类

分别在primary和secondary目录下编写对应数据库的实体类，如目录所示