JPA的多mysql数据源配置

• 1. 配置文件
     配置文件 application.yml 增加备用库的设置如下：

spring:
  datasource:
    #    driver-class-name: com.mysql.jdbc.Driver  老版
    primary:
      driver-class-name: com.mysql.cj.jdbc.Driver
      username: root
      password: 12345678
      # 一定是jdbc-url 要不然报错 数据源连接配置2.x和1.x的配置项是有区别的：2.x使用jdbc-url，
      # 而1.x版本使用 url。
      jdbc-url: jdbc:mysql://x.x.x.x:13306/your_primary_sql_name?charterEncoding=utf-8&useSSl=false&serverTimezone=Asia/Shanghai
    secondary:
      driver-class-name: com.mysql.cj.jdbc.Driver
      username: root
      password: 12345678
      jdbc-url: jdbc:mysql://y.y.y.y:13306/you_secondary_sql_name?charterEncoding=utf-8&useSSl=false&serverTimezone=Asia/Shanghai

注意：如果你在配置的时候发生了这个报错java.lang.IllegalArgumentException: jdbcUrl is required with driverClassName. 就是url配置项错误。2.x版本下，url配置项名称应该为jdbc-url。

• 2. 创建一个多数据源的配置类加载上述数据源配置
     比如我新建一个配置类：DataSourceConfig，内容如下：

@Configuration
public class DataSourceConfig {

    // @Primary注解指定了主数据源，就是当我们不特别指定哪个数据源的时候，就会使用这个Bean
    @Primary
    @Bean
    @ConfigurationProperties(prefix = "spring.datasource.primary")
    public DataSource primaryDataSource() {
        return DataSourceBuilder.create().build();
    }

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

}

• 3. 数据源primary配置类
     新建数据源primary配置类：JpaConfigPrimary，内容如下：

@Configuration
/* 使用 @EnableTransactionManagement 注解来进行 JPA 的配置，该注解中主要配置了三个属性：
   basePackages 用来指定 Repository 所在的位置（可以配置多个包）。
   entityManagerFactoryRef 用来指定实体类管理工厂 Bean 的名称。
   transactionManagerRef 用来指定事物管理器的引用名称，这里的引用名称就是 JpaConfigOne 类中注册的 Bean 的名称（默认的 Bean 名称为方法名）
 */
@EnableTransactionManagement
@EnableJpaRepositories(entityManagerFactoryRef="entityManagerFactoryPrimary",
        transactionManagerRef="transactionManagerPrimary",
        basePackages = {"com.tony.miaosuan.repository"})
public class JpaConfigPrimary {

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

    @Autowired
    private JpaProperties jpaProperties;
    @Autowired
    private HibernateProperties hibernateProperties;

    private Map<String, Object> getVendorProperties() {
        return hibernateProperties.determineHibernateProperties(jpaProperties.getProperties(), new HibernateSettings());
    }

    @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)
                .packages("com.tony.miaosuan.model")   //设置实体类所在位置
                .persistenceUnit("primaryPersistenceUnit")
                .properties(getVendorProperties())
                .build();
    }

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

}

• 4. 数据源secondary配置类
     新建数据源secondary配置类：JpaConfigSecondary，内容如下：

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(entityManagerFactoryRef="entityManagerFactorySecondary",
        transactionManagerRef="transactionManagerSecondary",
        basePackages = {"com.tony.miaosuan.repository2"})
public class JpaConfigSencondary {

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

    @Autowired
    private JpaProperties jpaProperties;
    @Autowired
    private HibernateProperties hibernateProperties;

    private Map<String, Object> getVendorProperties() {
        return hibernateProperties.determineHibernateProperties(jpaProperties.getProperties(), new HibernateSettings());
    }

    @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)
                .packages("com.tony.miaosuan.model2")  //设置实体类所在位置
                .persistenceUnit("secondaryPersistenceUnit")
                .properties(getVendorProperties())
                .build();
    }

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