前言

很多业务场景都需要使用到多数据库，本文介绍springboot对多数据源的使用。

pom.xml文件

和整合JPA的配置文件一样。

 <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

配置文件application.yml

server:
  port: 8080
spring:
  datasource:
    #主数据源
    primary:
      url: jdbc:mysql://localhost:3306/test?serverTimezone=GMT
      username: root
      password: 123456
      driver-class-name: com.mysql.jdbc.Driver
      type: com.zaxxer.hikari.HikariDataSource
    #次数据源
    secondary:
      url: jdbc:mysql://localhost:3306/test2?serverTimezone=GMT
      username: root
      password: 123456
      driver-class-name: com.mysql.jdbc.Driver
  jpa:
    #主jpa配置
    primary:
      show-sql: true
      properties:
        hibernate:
          hbm2ddl:
            auto: update
          dialect: org.hibernate.dialect.MySQL5InnoDBDialect
    #次jpa配置
    secondary:
      show-sql: true
      properties:
        hibernate:
          hbm2ddl:
            auto: update
          dialect: org.hibernate.dialect.MySQL5InnoDBDialect

配置数据源和JPA

主数据源配置

主数据源

1. @Primary：自动装配时当出现多个Bean候选者时，被注解为@Primary的Bean将作为首选者，否则将抛出异常。
2. @Qualifier：一般@Autowired和@Qualifier一起用，通过name取多个实例中的一个。
3. @ConfigurationProperties：根据配置文件中设置的属性，批量注入属性值。

@Configuration
public class PrimaryDataSourceConfig {

    /**
     * 扫描spring.datasource.primary开头的配置信息
     *
     * @return 数据源配置信息
     */
    @Primary
    @Bean(name = "primaryDataSourceProperties")
    @ConfigurationProperties(prefix = "spring.datasource.primary")
    public DataSourceProperties dataSourceProperties() {
        return new DataSourceProperties();
    }

    /**
     * 取主库数据源对象
     *
     * @param dataSourceProperties 注入名为primaryDataSourceProperties的bean
     * @return 数据源对象
     */
    @Primary
    @Bean(name = "primaryDataSource")
    public DataSource dataSource(@Qualifier("primaryDataSourceProperties") DataSourceProperties dataSourceProperties) {
        return dataSourceProperties.initializeDataSourceBuilder().build();
    }

    /**
     * 该方法仅在需要使用JdbcTemplate对象时选用
     *
     * @param dataSource 注入名为primaryDataSource的bean
     * @return 数据源JdbcTemplate对象
     */
    @Primary
    @Bean(name = "primaryJdbcTemplate")
    public JdbcTemplate jdbcTemplate(@Qualifier("primaryDataSource") DataSource dataSource) {
        return new JdbcTemplate(dataSource);
    }
}

主Jpa配置

1. @EnableTransactionManagement：使用注解@EnableTransactionManagement开启事务支持后，可以在访问数据库的Service方法上添加注解 @Transactional 使用事务。
2. @EnableJpaRepositories：用于Srping JPA的代码配置(详细介绍)

属性	功能
basePackage	用于配置扫描Repositories所在的package及子package。
entityManagerFactoryRef	实体管理工厂引用名称，对应到@Bean注解对应的方法。
transactionManagerRef	事务管理工厂引用名称，对应到@Bean注解对应的方法

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
        basePackages = PrimaryJpaConfig.REPOSITORY_PACKAGE,
        entityManagerFactoryRef = "primaryEntityManagerFactory",
        transactionManagerRef = "primaryTransactionManager"
)
public class PrimaryJpaConfig {

    static final String REPOSITORY_PACKAGE = "com.huzh.springbootjpamulidatasource.repository.primary";
    private static final String ENTITY_PACKAGE = "com.huzh.springbootjpamulidatasource.entity.primary";

    /**
     * 扫描spring.jpa.primary开头的配置信息
     *
     * @return jpa配置信息
     */
    @Primary
    @Bean(name = "primaryJpaProperties")
    @ConfigurationProperties(prefix = "spring.jpa.primary")
    public JpaProperties jpaProperties() {
        return new JpaProperties();
    }

    /**
     * 获取主库实体管理工厂对象
     *
     * @param primaryDataSource 注入名为primaryDataSource的数据源
     * @param jpaProperties     注入名为primaryJpaProperties的jpa配置信息
     * @param builder           注入EntityManagerFactoryBuilder
     * @return 实体管理工厂对象
     */
    @Primary
    @Bean(name = "primaryEntityManagerFactory")
    public LocalContainerEntityManagerFactoryBean entityManagerFactoryBean(
            @Qualifier("primaryDataSource") DataSource primaryDataSource,
            @Qualifier("primaryJpaProperties") JpaProperties jpaProperties,
            EntityManagerFactoryBuilder builder
    ) {
        return builder
                // 设置数据源
                .dataSource(primaryDataSource)
                // 设置jpa配置
                .properties(jpaProperties.getProperties())
                // 设置实体包名
                .packages(ENTITY_PACKAGE)
                // 设置持久化单元名，用于@PersistenceContext注解获取EntityManager时指定数据源
                .persistenceUnit("primaryPersistenceUnit").build();
    }

    /**
     * 获取实体管理对象
     *
     * @param factory 注入名为primaryEntityManagerFactory的bean
     * @return 实体管理对象
     */
    @Primary
    @Bean(name = "primaryEntityManager")
    public EntityManager entityManager(@Qualifier("primaryEntityManagerFactory") EntityManagerFactory factory) {
        return factory.createEntityManager();
    }

    /**
     * 获取主库事务管理对象
     *
     * @param factory 注入名为primaryEntityManagerFactory的bean
     * @return 事务管理对象
     */
    @Primary
    @Bean(name = "primaryTransactionManager")
    public PlatformTransactionManager transactionManager(@Qualifier("primaryEntityManagerFactory") EntityManagerFactory factory) {
        return new JpaTransactionManager(factory);
    }
}

次数据源配置

次数据源

@Configuration
public class SecondaryDataSourceConfig {

    /**
     * 扫描spring.datasource.secondary开头的配置信息
     *
     * @return 数据源配置信息
     */
    @Bean(name = "secondaryDataSourceProperties")
    @ConfigurationProperties(prefix = "spring.datasource.secondary")
    public DataSourceProperties dataSourceProperties() {
        return new DataSourceProperties();
    }

    /**
     * 获取次数据源对象
     *
     * @param dataSourceProperties 注入名为secondaryDataSourceProperties的bean
     * @return 数据源对象
     */
    @Bean("secondaryDataSource")
    public DataSource dataSource(@Qualifier("secondaryDataSourceProperties") DataSourceProperties dataSourceProperties) {
        return dataSourceProperties.initializeDataSourceBuilder().build();
    }

    /**
     * 该方法仅在需要使用JdbcTemplate对象时选用
     *
     * @param dataSource 注入名为secondaryDataSource的bean
     * @return 数据源JdbcTemplate对象
     */
    @Bean(name = "secondaryJdbcTemplate")
    public JdbcTemplate jdbcTemplate(@Qualifier("secondaryDataSource") DataSource dataSource) {
        return new JdbcTemplate(dataSource);
    }
}

从Jpa配置

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
        basePackages = SecondaryJpaConfig.REPOSITORY_PACKAGE,
        entityManagerFactoryRef = "secondaryEntityManagerFactory",
        transactionManagerRef = "secondaryTransactionManager"
)
public class SecondaryJpaConfig {

    static final String REPOSITORY_PACKAGE = "com.huzh.springbootjpamulidatasource.repository.secondary";
    private static final String ENTITY_PACKAGE = "com.huzh.springbootjpamulidatasource.entity.secondary";

    /**
     * 扫描spring.jpa.secondary
     *
     * @return jpa配置信息
     */
    @Bean(name = "secondaryJpaProperties")
    @ConfigurationProperties(prefix = "spring.jpa.secondary")
    public JpaProperties jpaProperties() {
        return new JpaProperties();
    }

    /**
     * 获取次库实体管理工厂对象
     *
     * @param secondaryDataSource 注入名为secondaryDataSource的数据源
     * @param jpaProperties       注入名为secondaryJpaProperties的jpa配置信息
     * @param builder             注入EntityManagerFactoryBuilder
     * @return 实体管理工厂对象
     */
    @Bean(name = "secondaryEntityManagerFactory")
    public LocalContainerEntityManagerFactoryBean entityManagerFactory(
            @Qualifier("secondaryDataSource") DataSource secondaryDataSource,
            @Qualifier("secondaryJpaProperties") JpaProperties jpaProperties,
            EntityManagerFactoryBuilder builder
    ) {
        return builder
                // 设置数据源
                .dataSource(secondaryDataSource)
                // 设置jpa配置
                .properties(jpaProperties.getProperties())
                // 设置实体包名
                .packages(ENTITY_PACKAGE)
                // 设置持久化单元名，用于@PersistenceContext注解获取EntityManager时指定数据源
                .persistenceUnit("secondaryPersistenceUnit").build();
    }

    /**
     * 获取实体管理对象
     *
     * @param factory 注入名为secondaryEntityManagerFactory的bean
     * @return 实体管理对象
     */
    @Bean(name = "secondaryEntityManager")
    public EntityManager entityManager(@Qualifier("secondaryEntityManagerFactory") EntityManagerFactory factory) {
        return factory.createEntityManager();
    }

    /**
     * 获取主库事务管理对象
     *
     * @param factory 注入名为secondaryEntityManagerFactory的bean
     * @return 事务管理对象
     */
    @Bean(name = "secondaryTransactionManager")
    public PlatformTransactionManager transactionManager(@Qualifier("secondaryEntityManagerFactory") EntityManagerFactory factory) {
        return new JpaTransactionManager(factory);
    }
}

实体类

主库实体类

@Entity
@Table(name="city")
public class City {

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int cityId;
    private String cityName;
    private String cityIntroduce;

    public City(int cityId, String cityName, String cityIntroduce) {
        this.cityId = cityId;
        this.cityName = cityName;
        this.cityIntroduce = cityIntroduce;
    }

    public City(String cityName, String cityIntroduce) {
        this.cityName = cityName;
        this.cityIntroduce = cityIntroduce;
    }

    public City() {
    }

    public int getCityId() {
        return cityId;
    }

    public void setCityId(int cityId) {
        this.cityId = cityId;
    }

    public String getCityName() {
        return cityName;
    }

    public void setCityName(String cityName) {
        this.cityName = cityName;
    }

    public String getCityIntroduce() {
        return cityIntroduce;
    }

    public void setCityIntroduce(String cityIntroduce) {
        this.cityIntroduce = cityIntroduce;
    }
}

从库实体类

@Entity
@Table(name = "house")
public class House {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private int houseId;
    private String houseName;
    private String houseIntroduce;

    public int getHouseId() {
        return houseId;
    }

    public void setHouseId(int houseId) {
        this.houseId = houseId;
    }

    public String getHouseName() {
        return houseName;
    }

    public void setHouseName(String houseName) {
        this.houseName = houseName;
    }

    public String getHouseIntroduce() {
        return houseIntroduce;
    }

    public void setHouseIntroduce(String houseIntroduce) {
        this.houseIntroduce = houseIntroduce;
    }

    public House(String houseName, String houseIntroduce) {
        this.houseName = houseName;
        this.houseIntroduce = houseIntroduce;
    }
}

Repository类

主库类

public interface CityRepository extends JpaRepository<City,Integer> {
}

从库类

public interface HouseRepository extends JpaRepository<House, Integer> {
}

Controller类

@RestController
public class TestController {

    @Autowired
    CityRepository cityRepository;

    @Autowired
    HouseRepository houseRepository;

    @GetMapping("/testDataSource")
    public String testDataSource() {
        City city = new City("北京", "中国首都");
        cityRepository.save(city);
        return "success";
    }

    @GetMapping("/testDataSource2")
    public String testDataSource2() {
        House house = new House("豪宅", "特别大的豪宅");
        houseRepository.save(house);
        return "success";
    }

}