Springboot连接两个数据库（以Mysql和H2数据库为例）

在Spring Boot中，你可以配置多个数据源以连接两个不同的数据库。以下是一个配置两个数据源（Mysql和H2）的示例：

1. 在application.properties或application.yml中配置两个数据源的基本属性：

# Mysql 数据源配置
spring.datasource.mysql.jdbc-url=jdbc:mysql://localhost:3306/mydb
spring.datasource.mysql.username=root
spring.datasource.mysql.password=yourpassword
spring.datasource.mysql.driver-class-name=com.mysql.cj.jdbc.Driver
 
# H2 数据源配置
spring.datasource.h2.url=jdbc:h2:mem:testdb
spring.datasource.h2.driver-class-name=org.h2.Driver
spring.datasource.h2.username=sa
spring.datasource.h2.password=

2. 配置两个DataSource Bean：

@Configuration
public class DataSourceConfig {
 
    @Bean(name = "mysqlDataSource")
    @Primary
    @ConfigurationProperties(prefix = "spring.datasource.mysql")
    public DataSource mysqlDataSource() {
        return DataSourceBuilder.create().build();
    }
 
    @Bean(name = "h2DataSource")
    @ConfigurationProperties(prefix = "spring.datasource.h2")
    public DataSource h2DataSource() {
        return DataSourceBuilder.create().build();
    }
}

3. 配置两个JpaRepository接口，分别使用@EnableJpaRepositories注解指定不同的数据源：

@EnableJpaRepositories(
        basePackages = "com.yourpackage.mysql",
        entityManagerFactoryRef = "mysqlEntityManager",
        transactionManagerRef = "mysqlTransactionManager"
)
public class MysqlConfig {
 
    @Bean(name = "mysqlEntityManager")
    @Primary
    public LocalContainerEntityManagerFactoryBean mysqlEntityManager(
            EntityManagerFactoryBuilder builder) {
        return builder
                .dataSource(mysqlDataSource())
                .packages("com.yourpackage.mysql")
                .persistenceUnit("mysql")
                .build();
    }
 
    @Bean(name = "mysqlTransactionManager")
    @Primary
    public PlatformTransactionManager mysqlTransactionManager(
            @Qualifier("mysqlEntityManager") EntityManagerFactory entityManagerFactory) {
        return new JpaTransactionManager(entityManagerFactory);
    }
}
 
@EnableJpaRepositories(
        basePackages = "com.yourpackage.h2",
        entityManagerFactoryRef = "h2EntityManager",
        transactionManagerRef = "h2TransactionManager"
)
public class H2Config {
 
    @Bean(name = "h2EntityManager