Spring Boot 多数据源配置（JPA）

前言

前置环境

pom

yml

Entity

Dao

Config

Controller

演示

前言

一般一个系统至少有一个数据源，用来持久化业务数据以及查询。单个数据源的系统很常见，在 Spring Boot 框架下配置也很简单。在约定大于配置这个思想下，只需要在配置文件中简单配置下数据库连接信息就行了。

除了单数据源系统，在实际工作中，还会遇到多数据源系统。有可能是因为业务需要，以实际中做过的资产清查相关的项目为例，数据的存储分成了两个库，一个当前库和归档库，系统就需要配置两个数据源来满足业务需求。也有可能是技术架构，比如 MySQL 数据库使用了主从复制架构来实现读写分离，然后在应用层做分流，就需要配置主库和从库数据源，并在代码中决定使用哪个库进行数据库操作。

以下是Spring Boot JPA 多数据源的配置教程

前置环境

JDK8 + SringBoot2 + MySQL8

分别创建数据库 test1 test2

分别在两个数据库中创建 user 表

create table user (
id int auto_increment primary key,
username varchar(255),
password varchar(255)
);

在test1.user 表中插入数据

insert into user(username, password) values('张三', '123456');

在test2.user 表中插入数据

insert into user(username, password) values('李四', '123456');

pom

    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>${spring-boot.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>
 
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
 
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
 
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
    <dependencies>

yml

server:
  port: 8888

spring:
  datasource:
    primary:
      url: jdbc:mysql://localhost:3306/test1?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=UTC&allowPublicKeyRetrieval=true
      username: root
      password: mysql
      driver-class-name: com.mysql.cj.jdbc.Driver
    secondary:
      url: jdbc:mysql://localhost:3306/test2?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=UTC&allowPublicKeyRetrieval=true
      username: root
      password: mysql
      driver-class-name: com.mysql.cj.jdbc.Driver

  jpa:
    primary:
      show-sql: true
      properties:
        hibernate:
          hbm2ddl:
            auto: update
          dialect: org.hibernate.dialect.MySQL5InnoDBDialect
    secondary:
      show-sql: true
      properties:
        hibernate:
          hbm2ddl:
            auto: update
          dialect: org.hibernate.dialect.MySQL5InnoDBDialect

Entity

主库和从库的实体类需要放在不同的包下，以本文为例

主库的实体类包路径为：com.jpa.entity.primary

@Entity
@Table ( name = "user")
public class PrimaryUserEntity {
    private Integer id;
    private String username;
    private String password;

    @Id
    @GeneratedValue ( strategy = GenerationType.IDENTITY)
    @Column ( name = "id" )
    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    @Basic
    @Column ( name = "username" )
    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    @Basic
    @Column ( name = "password" )
    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

}

从库的实体类包路径为：com.jpa.entity.secondary

@Entity
@Table ( name = "user")
public class SecondaryUserEntity {
    private Integer id;
    private String username;
    private String password;

    @Id
    @GeneratedValue ( strategy = GenerationType.IDENTITY)
    @Column ( name = "id" )
    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    @Basic
    @Column ( name = "username" )
    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    @Basic
    @Column ( name = "password" )
    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

}

Dao

主库和从库的Dao需要放在不同的包下，以本文为例

主库的Dao包路径为：com.jpa.dao.primary

@Repository (value = IPrimaryUserDao.DAO_BEAN_NAME )
public interface IPrimaryUserDao extends JpaRepository<PrimaryUserEntity, Integer> {
    String DAO_BEAN_NAME = "primaryUserDao";
}

从库的Dao包路径为：com.jpa.dao.secondary

@Repository (value = ISecondaryUserDao.DAO_BEAN_NAME )
public interface ISecondaryUserDao extends JpaRepository<SecondaryUserEntity, Integer> {
    String DAO_BEAN_NAME = "secondaryUserDao";
}

Config

记得将类中的两个包路径修改成自己项目的包路径

REPOSITORY_PACKAGE

ENTITY_PACKAGE

主库数据源配置

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

    private static final String REPOSITORY_PACKAGE = "com.jpa.dao.primary";
    private static final String ENTITY_PACKAGE = "com.jpa.entity.primary";

    //--------------数据源配置-------------------

    /**
     * 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();
    }


    /**
     * 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 JpaTransactionManager transactionManager(@Qualifier("primaryEntityManagerFactory") EntityManagerFactory factory) {
        return new JpaTransactionManager(factory);
    }
}

从库数据源配置

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
        basePackages = SecondaryDatasourceAndJpaConfig.REPOSITORY_PACKAGE,
        entityManagerFactoryRef = "secondaryEntityManagerFactory",
        transactionManagerRef = "secondaryTransactionManager"
)
public class SecondaryDatasourceAndJpaConfig {
    
    static final String REPOSITORY_PACKAGE = "com.jpa.dao.secondary";
    static final String ENTITY_PACKAGE = "com.jpa.entity.secondary";

    //--------------数据源配置-------------------

    /**
     * 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();
    }

    /**
     * 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 JpaTransactionManager transactionManager(@Qualifier("secondaryEntityManagerFactory") EntityManagerFactory factory) {
        return new JpaTransactionManager(factory);
    }
}

Controller

主库

@RestController
@RequestMapping(value = "/primary")
public class PrimaryJpaController {

    @Resource
    private IPrimaryUserDao primaryUserDao;

    @RequestMapping(value = "/findAll", method = RequestMethod.GET)
    public List<PrimaryUserEntity> findAll() {
        return primaryUserDao.findAll();
    }
}

从库

@RestController
@RequestMapping(value = "/secondary")
public class SecondaryJpaController{

    @Resource
    private ISecondaryUserDao secondaryUserDao;

    @RequestMapping(value = "/findAll", method = RequestMethod.GET)
    public List<SecondaryUserEntity> findAll() {
        return secondaryUserDao.findAll();
    }
}