Springboot实现多数据源切换详情

下面我将为您详细介绍Spring Boot实现多数据源切换的完整攻略，包括以下内容：

1. 配置数据源
2. 配置JdbcTemplate
3. 配置JPA
4. 配置事务管理器
5. 实现多数据源切换

1. 配置数据源

Spring Boot默认采用HikariCP作为连接池，我们需要分别配置多个数据源并注入到Spring中。我们可以在application.properties文件中配置多个数据源：

# 主数据源
spring.datasource.primary.jdbc-url=jdbc:mysql://localhost:3306/primaryDataSource
spring.datasource.primary.username=root
spring.datasource.primary.password=123456
spring.datasource.primary.driver-class-name=com.mysql.jdbc.Driver

# 次数据源
spring.datasource.secondary.jdbc-url=jdbc:mysql://localhost:3306/secondaryDataSource
spring.datasource.secondary.username=root
spring.datasource.secondary.password=123456
spring.datasource.secondary.driver-class-name=com.mysql.jdbc.Driver

2. 配置JdbcTemplate

对于同一类型的数据源（例如都是MySQL），我们可以使用JdbcTemplate来操作数据库。我们需要在Spring中注入多个JdbcTemplate，以便于使用。

@Configuration
public class DataSourceConfig {

    @Bean(name = "primaryJdbcTemplate")
    public JdbcTemplate primaryJdbcTemplate(
            @Qualifier("primaryDataSource") DataSource dataSource) {
        return new JdbcTemplate(dataSource);
    }

    @Bean(name = "secondaryJdbcTemplate")
    public JdbcTemplate secondaryJdbcTemplate(
            @Qualifier("secondaryDataSource") DataSource dataSource) {
        return new JdbcTemplate(dataSource);
    }

}

3. 配置JPA

对于不同类型的数据源（例如MySQL和Oracle），我们可以使用JPA来操作数据库。我们需要在Spring中注入多个JPA EntityManagerFactory，并使用@Primary注解指定主数据源的EntityManagerFactory。

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

    @Primary
    @Bean(name = "primaryDataSource")
    @ConfigurationProperties(prefix = "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.primary.entity")
                .persistenceUnit("primary")
                .build();
    }

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

}

4. 配置事务管理器

对于需要使用事务的操作，我们需要配置一个事务管理器。

@Configuration
@EnableTransactionManagement
public class TransactionManagerConfig {

    @Bean(name = "primaryTransactionManager")
    @Autowired
    @Primary
    public PlatformTransactionManager primaryTransactionManager(@Qualifier("primaryDataSource") DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }

    @Bean(name = "secondaryTransactionManager")
    public PlatformTransactionManager secondaryTransactionManager(@Qualifier("secondaryDataSource") DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }

}

5. 实现多数据源切换

我们需要使用AOP切面来实现多数据源切换。我们需要为每个数据源配置一个数据源切换器，并使用@Around注解为每个方法添加数据源切换的逻辑。

@Aspect
@Component
public class DataSourceAspect {

    @Pointcut("execution(* com.example.primary..*.*(..))")
    public void primaryPointcut() {}

    @Pointcut("execution(* com.example.secondary..*.*(..))")
    public void secondaryPointcut() {}

    @Around("primaryPointcut()")
    public Object doAroundPrimary(ProceedingJoinPoint pjp) throws Throwable {
        try {
            DataSourceContextHolder.setDataSourceType("primaryDataSource");
            return pjp.proceed();
        } finally {
            DataSourceContextHolder.clearDataSourceType();
        }
    }

    @Around("secondaryPointcut()")
    public Object doAroundSecondary(ProceedingJoinPoint pjp) throws Throwable {
        try {
            DataSourceContextHolder.setDataSourceType("secondaryDataSource");
            return pjp.proceed();
        } finally {
            DataSourceContextHolder.clearDataSourceType();
        }
    }

}

以上就是Spring Boot实现多数据源切换的完整攻略。下面给出两个示例：

1. 使用JdbcTemplate操作MySQL

@RestController
public class UserController {

    @Autowired
    @Qualifier("primaryJdbcTemplate")
    private JdbcTemplate primaryJdbcTemplate;

    @Autowired
    @Qualifier("secondaryJdbcTemplate")
    private JdbcTemplate secondaryJdbcTemplate;

    @RequestMapping("/testPrimary")
    public String testPrimary() {
        String sql = "SELECT COUNT(*) FROM user";
        int count = primaryJdbcTemplate.queryForObject(sql, Integer.class);
        return "Primary DataSource Count: " + count;
    }

    @RequestMapping("/testSecondary")
    public String testSecondary() {
        String sql = "SELECT COUNT(*) FROM user";
        int count = secondaryJdbcTemplate.queryForObject(sql, Integer.class);
        return "Secondary DataSource Count: " + count;
    }

}

1. 使用JPA操作MySQL和Oracle

@RestController
public class UserController {

    @Autowired
    @Qualifier("primaryEntityManagerFactory")
    private EntityManagerFactory primaryEntityManagerFactory;

    @Autowired
    @Qualifier("secondaryEntityManagerFactory")
    private EntityManagerFactory secondaryEntityManagerFactory;

    @RequestMapping("/testPrimary")
    @Transactional("primaryTransactionManager")
    public String testPrimary() {
        EntityManager entityManager = primaryEntityManagerFactory.createEntityManager();
        User user = entityManager.find(User.class, 1L);
        entityManager.close();
        return "Primary DataSource User: " + user.getName();
    }

    @RequestMapping("/testSecondary")
    @Transactional("secondaryTransactionManager")
    public String testSecondary() {
        EntityManager entityManager = secondaryEntityManagerFactory.createEntityManager();
        Department dept = entityManager.find(Department.class, 1L);
        entityManager.close();
        return "Secondary DataSource Dept Name: " + dept.getName();
    }

}

希望这些内容能够对您有所帮助。