【Spring】如何同时启用多个数据源

Java Spring

发布日期: 2025-02-24

更新日期: 2025-02-25

文章字数: 1.1k

阅读时长: 5 分

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问题背景

在实际应用中，可能需要连接多个数据库，例如一个用于主数据存储，另一个用于日志或分析数据。Spring 提供了灵活的方式来配置多个数据源，以便在同一个应用中使用。

解决方案

1. 添加依赖

首先，确保在 pom.xml 中添加了 Spring Data JPA 和数据库驱动的依赖。例如，如果使用 MySQL，可以添加如下依赖：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
</dependency>

2. 配置数据源

在 application.yml 或 application.properties 中配置多个数据源。例如：

spring:
  datasource:
    primary:
      url: jdbc:mysql://localhost:3306/primary_db
      username: root
      password: password
      driver-class-name: com.mysql.cj.jdbc.Driver
    secondary:
      url: jdbc:mysql://localhost:3306/secondary_db
      username: root
      password: password
      driver-class-name: com.mysql.cj.jdbc.Driver

3. 创建数据源配置类

为每个数据源创建配置类，并使用 @Primary 注解标记主数据源。

import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.orm.jpa.HibernatePropertiesCustomizer;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.orm.jpa.EntityManagerFactoryBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
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 javax.persistence.EntityManagerFactory;

@Configuration
@EnableJpaRepositories(
        basePackages = "com.example.repository.primary",
        entityManagerFactoryRef = "primaryEntityManagerFactory",
        transactionManagerRef = "primaryTransactionManager"
)
public class PrimaryDataSourceConfig {

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

    @Primary
    @Bean(name = "primaryEntityManagerFactory")
    public LocalContainerEntityManagerFactoryBean primaryEntityManagerFactory(
            EntityManagerFactoryBuilder builder,
            @Qualifier("primaryDataSource") DataSource dataSource) {
        return builder
                .dataSource(dataSource)
                .packages("com.example.model.primary")
                .persistenceUnit("primary")
                .build();
    }

    @Primary
    @Bean(name = "primaryTransactionManager")
    public PlatformTransactionManager primaryTransactionManager(
            @Qualifier("primaryEntityManagerFactory") EntityManagerFactory primaryEntityManagerFactory) {
        return new JpaTransactionManager(primaryEntityManagerFactory);
    }
}

4. 创建第二个数据源配置类

import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.orm.jpa.HibernatePropertiesCustomizer;
import org.springframework.boot.context.properties.ConfigurationProperties;
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 javax.persistence.EntityManagerFactory;

@Configuration
@EnableJpaRepositories(
        basePackages = "com.example.repository.secondary",
        entityManagerFactoryRef = "secondaryEntityManagerFactory",
        transactionManagerRef = "secondaryTransactionManager"
)
public class SecondaryDataSourceConfig {

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

    @Bean(name = "secondaryEntityManagerFactory")
    public LocalContainerEntityManagerFactoryBean secondaryEntityManagerFactory(
            EntityManagerFactoryBuilder builder,
            @Qualifier("secondaryDataSource") DataSource dataSource) {
        return builder
                .dataSource(dataSource)
                .packages("com.example.model.secondary")
                .persistenceUnit("secondary")
                .build();
    }

    @Bean(name = "secondaryTransactionManager")
    public PlatformTransactionManager secondaryTransactionManager(
            @Qualifier("secondaryEntityManagerFactory") EntityManagerFactory secondaryEntityManagerFactory) {
        return new JpaTransactionManager(secondaryEntityManagerFactory);
    }
}

5. 创建实体和仓库

为每个数据源创建相应的实体类和仓库接口。例如：

// Primary Data Source Entity
@Entity
public class PrimaryEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    // getters and setters
}

// Secondary Data Source Entity
@Entity
public class SecondaryEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String description;
    // getters and setters
}

// Primary Repository
public interface PrimaryRepository extends JpaRepository<PrimaryEntity, Long> {
}

// Secondary Repository
public interface SecondaryRepository extends JpaRepository<SecondaryEntity, Long> {
}

实际应用示例

1. 使用服务层

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class MyService {

    @Autowired
    private PrimaryRepository primaryRepository;

    @Autowired
    private SecondaryRepository secondaryRepository;

    public void saveData() {
        PrimaryEntity primaryEntity = new PrimaryEntity();
        primaryEntity.setName("Primary Data");
        primaryRepository.save(primaryEntity);

        SecondaryEntity secondaryEntity = new SecondaryEntity();
        secondaryEntity.setDescription("Secondary Data");
        secondaryRepository.save(secondaryEntity);
    }
}

2. 测试验证

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest
public class MyServiceTest {

    @Autowired
    private MyService myService;

    @Test
    public void testSaveData() {
        myService.saveData();
        // 验证数据是否保存成功
    }
}