SpringBoot+JPA 实现配置多数据源

之前在介绍使用springboot和Spring-data-jpa时，使用了单数据源。在单数据源的情况下，Spring Boot的配置非常简单，只需要在application.properties文件中配置连接参数即可。但是往往随着业务量发展，我们通常会进行数据库拆分或是引入其他数据库，从而我们需要配置多个数据源，下面基于之前的Spring-data-jpa例子介绍多数据源的配置方式。

多数据源配置

创建一个Spring配置类，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.primary.datasource开头的配置，第二数据源配置为spring.secondary.datasource开头的配置。

DataSourcesConfig配置类为：

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

import javax.sql.DataSource;

/**
 * @Author:dyz Date:9:34 2019/8/5
 */

/**
 * 数据源的配置
 */
@Configuration
public class DataSourcesConfig {

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

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

}

 对应的application.yml配置如下：

# 多数据源配置
#primary
spring:
  primary:
    datasource:
      driver-class-name: com.mysql.jdbc.Driver
      jdbc-url: jdbc:mysql://172.16.**.**:63306/hrm?useSSL=false&characterEncoding=utf-8
      username: ****
      password: *****

  #secondary
  secondary:
    datasource:
      driver-class-name: com.mysql.jdbc.Driver
      jdbc-url: jdbc:mysql://172.16.**.**:**/autoui?useSSL=false&characterEncoding=utf-8
      username: *****
      password: *******

这里需要注意的是：原来的url字段需要改成jdbc-url。

新增数据源一的JPA配置，注意两处注释的地方，用于指定数据源对应的Entity实体和Repository定义位置，用@Primary区分主数据源。

/**
 * 数据源一
 */
@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
        entityManagerFactoryRef = "entityManagerFactoryPrimary",
        transactionManagerRef = "transactionManagerPrimary",
        basePackages = {"com.modules.system.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())
                .packages("com.modules.system.domain.primary") //设置实体类所在位置
                .persistenceUnit("primaryPersistenceUnit")
                .build();
    }

    @Autowired
    private JpaProperties jpaProperties;

    private Map<String, String> getVendorProperties() {
        return jpaProperties.getProperties();
    }

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

 新增数据源二的JPA配置，内容和数据源一类似。

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;

/**
 * 数据源二
 */
@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
        entityManagerFactoryRef = "entityManagerFactorySecondary",
        transactionManagerRef = "transactionManagerSecondary",
        basePackages = {"com.modules.system.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())
                .packages("com.modules.system.domain.secondary") //设置实体类所在位置
                .persistenceUnit("secondaryPersistenceUnit")
                .build();
    }

    @Autowired
    private JpaProperties jpaProperties;

    private Map<String, String> getVendorProperties() {
        return jpaProperties.getProperties();
    }

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

然后在对应的包下面创建实体类和数据访问接口，主数据源的数据访问接口位于：com.modules.system.repository.primary，实体类位于：com.modules.system.domain.primary；次数据源的数据访问接口位于：com.modules.system.repository.secondary，实体类位于：com.modules.system.domain.secondary。

最后我们在调用数据访问接口的时候，选择调用不同包下面的数据访问接口，就可以实现访问不同的数据源。