基于boot的多数据源的配置与使用

应用场景：在同一个应用中有时候不仅仅需要访问一个的数据库，还需要连接多个数据库，这个时候就需要通过配置多个数据源来满足应用场景。

使用JPA来操作数据库，引入依赖：

spring-boot-starter-data-jpa

1、创建两个数据库，并建立对应的表t_user

 

 2、项目目录结构：

3、在application.properties中配置两个数据源：

spring.datasource.primary.jdbc-url = jdbc:mysql://127.0.0.1:3306/test1?serverTimezone=UTC&useUnicode=true&characterEncoding=utf8&useSSL=false
spring.datasource.primary.username = admin
spring.datasource.primary.password = admin
spring.datasource.primary.driver-class-name = com.mysql.cj.jdbc.Driver

spring.datasource.secondary.jdbc-url = jdbc:mysql://127.0.0.1:3306/test2?serverTimezone=UTC&useUnicode=true&characterEncoding=utf8&useSSL=false
spring.datasource.secondary.username = admin
spring.datasource.secondary.password = admin
spring.datasource.secondary.driver-class-name = com.mysql.cj.jdbc.Driver

#SQL输出
spring.jpa.show-sql=true
#注意这个地方是update不是create，如果是create会发现每次都会把之前的数据删除掉。
spring.jpa.properties.hibernate.hbm2ddl.auto=update
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5InnoDBDialect
#format 以下SQL进行输出
spring.jpa.properties.hibernate.format_sql=true

 3、建立实体类User

package com.example.jtademo.model;

import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;

import javax.persistence.*;

/**
 * @Auther: ecchen
 * @Date: 2019/12/11 13:39
 * @Description:
 */
@Entity(name = "t_user")
@Data
@Builder
@AllArgsConstructor
@NoArgsConstructor
public class User {
    @Id
    private Long id;
    @Column(name = "user_name",nullable = false,unique = true)
    private String userName;
    @Column(name = "password",nullable = false)
    private String passWord;
    @Column(name = "email",nullable = false,unique = true)
    private String email;
    @Column(name = "nick_name",nullable = false,unique = true)
    private String nickName;
    @Column(name = "reg_time",nullable = false)
    private String regTime;
}

4、建立repository1,repository2一样。

package com.example.jtademo.repository.test1;

import com.example.jtademo.model.User;
import org.springframework.data.jpa.repository.JpaRepository;

/**
 * @Auther: ecchen
 * @Date: 2019/12/11 11:20
 * @Description:
 */
public interface UserTest1Repository extends JpaRepository<User,Long> {
}

5、建立配置类DataSourceConfig，在项目启动时运行初始化数据库资源。

@Configuration
public class DataSourceConfig {
    @Autowired
    private JpaProperties jpaProperties;
    @Autowired
    private HibernateProperties hibernateProperties;

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

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

    @Bean(name = "vendorProperties")
    public Map<String,Object> getVendorProperties(){
        return hibernateProperties.determineHibernateProperties(jpaProperties.getProperties(),new HibernateSettings());
    }

}

6、建立默认数据源配置类PrimaryConfig，将配置文件中的信息注入到类中

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
        entityManagerFactoryRef = "entityManagerFactoryPrimary",
        transactionManagerRef = "transactionManagerPrimary",
        basePackages = {"com.example.jtademo.repository.test1"}
)
public class PrimaryConfig {
    @Autowired
    @Qualifier("primaryDataSource")
    private DataSource primaryDataSource;
    @Autowired
    @Qualifier("vendorProperties")
    private Map<String,Object> vendorProperties;
    @Bean(name = "entityManagerFactoryPrimary")
    @Primary
    public LocalContainerEntityManagerFactoryBean entityManagerFactoryPrimary(EntityManagerFactoryBuilder builder){
        return builder
                .dataSource(primaryDataSource)
                .properties(vendorProperties)
                .packages("com.example.jtademo.model")
                .persistenceUnit("primaryPersistenceUnit")
                .build();
    }
    @Bean(name = "entityManagerPrimary")
    @Primary
    public EntityManager entityManager(EntityManagerFactoryBuilder builder){
        return entityManagerFactoryPrimary(builder).getObject().createEntityManager();
    }

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

　　

最后一步@EnableJpaRepositories最为关键，将我们在类中配置好的 EntityManager 和事务信息注入到对应数据源的 repository 目录下，这样此目录下的 repository 就会拥有对应数据源和事务的信息。

EntityManager是JPA中负责数据库增删改查的接口类，basePackages可以支持多个repository的连写，以逗号分隔。

SecondaryConfig和PrimaryConfig雷同，不同点在于没有@Primary注解。

至此，编码完成，可以编写测试类来验证了。

测试类如下：

    @Test
    public void testJpaSaveMethod(){
        User user1 = new User();
        user1.setId(3L);
        user1.setUserName("ec_chen6");
        user1.setEmail("345116@email.com");
        user1.setNickName("昵称6");
        user1.setPassWord("1452146");
        user1.setRegTime("2019-12-16");
        userTest1Repository.save(user1);
        User user2 = new User();
        user2.setId(3L);
        user2.setUserName("ec_chen3");
        user2.setEmail("3451@email24.com");
        user2.setNickName("昵称235");
        user2.setPassWord("14521455");
        user2.setRegTime("2019-12-15");
        userTest2Repository.save(user2);
    }

运行结果如下：

运行测试类成功，数据库分别存入一条数据。