多数据源配置H2 Mysql

H2->Mysql数据迁移

需求背景
环境说明
实现过程

需求背景

最近有一需求，原本项目中由于某些原因使用嵌入式数据库H2，鉴于嵌入式数据库可靠性以及不方便管理等因素，需要将数据库迁移到Mysql。

环境说明

SpringBoot：3.0.2

JDK：17

H2：2.1.214

spring-boot-starter-data-jpa：3.0.2

Mysql：8.0.32

实现过程

配置调整

原配置

pom.xml

xml 复制代码

<!-- 省略其他依赖... -->
<dependency>
    <groupId>com.h2database</groupId>
    <artifactId>h2</artifactId>
    <version>2.1.214</version>
    <scope>runtime</scope>
</dependency>

dev.yml

yaml 复制代码

spring:
  datasource:
    url: jdbc:h2:file:./data/cloak-ab
    driver-class-name: org.h2.Driver
    username: root
    password: root789456
  jpa:
    database: h2
    hibernate:
      ddl-auto: update
    show-sql: true
  h2:
    console:
      path: /h2-console
      enabled: true
      settings:
        web-allow-others: true
        trace: true

修改配置

修改后pom.xml

xml 复制代码

<!-- 省略其他依赖... -->
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.32</version>
</dependency>
<dependency>
    <groupId>com.h2database</groupId>
    <artifactId>h2</artifactId>
    <version>2.1.214</version>
    <scope>runtime</scope>
</dependency>

修改后dev.yml

yaml 复制代码

spring:
  datasource:
    url: jdbc:mysql://192.168.0.80:3306/cloak_ab?useUnicode=true&characterEncoding=utf-8&useSSL=true&serverTimezone=GMT%2B8&allowMultiQueries=true
    driver-class-name: com.mysql.cj.jdbc.Driver
    username: root
    password: root789456
  jpa:
  	# 此处有修改
    database: mysql
    hibernate:
      ddl-auto: update
    show-sql: true
  h2:
    console:
      path: /h2-console
      enabled: true
      settings:
        web-allow-others: true
        trace: true

主要修改点有三处：

①添加Mysql连接依赖
②数据库的连接地址和数据库驱动
③jpa使用的数据库

代码调整

新增DatasourceConfig配置类

配置Mysql主数据源，H2次数据源

DatasourceConfig.java

java 复制代码

import lombok.Data;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.jdbc.DataSourceBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.jdbc.core.JdbcTemplate;

import javax.sql.DataSource;

@Configuration
public class DatasourceConfig {

    @Data
    @Configuration
    @ConfigurationProperties(prefix="spring.datasource")
    public static class MasterDatasourceProperties {
        private String url;
        private String driverClassName;
        private String username;
        private String password;
    }

    @Bean
    @Primary
    public DataSource dataSource(MasterDatasourceProperties masterDatasourceProperties) {
        return DataSourceBuilder.create()
                .driverClassName(masterDatasourceProperties.getDriverClassName())
                .url(masterDatasourceProperties.getUrl())
                .username(masterDatasourceProperties.getUsername())
                .password(masterDatasourceProperties.getPassword())
                .build();
    }

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

    @Bean(name = "secondaryDataSource")
    @Qualifier("secondaryDataSource")
    public DataSource secondaryDataSource() {
        return DataSourceBuilder.create()
                .url("jdbc:h2:file:./data/cloak-ab")
                .driverClassName("org.h2.Driver")
                .username("root")
                .password("root789456")
                .build();
    }

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

}

Mysql主数据源添加@Primary注解，jpa使用的默认是主数据源，如此一来jpa操作的就是Mysql数据库了。

使用secondaryJdbcTemplate

java 复制代码

	@Autowired
    private AppParamDao appParamDao;
	@Autowired
    @Qualifier("secondaryJdbcTemplate")
    protected JdbcTemplate secondaryJdbcTemplate;

	@Override
    public void h2ToMysql() {
        String sql = "select * from app_param";
        List<AppParam> appParams = secondaryJdbcTemplate.query(sql, new BeanPropertyRowMapper<>(AppParam.class));
        appParamDao.saveAllAndFlush(appParams);
    }

此时secondaryJdbcTemplate操作的就是H2数据库，而appParamDao操作的就是Mysql数据库

AppParamDao.java

java 复制代码

import org.springframework.data.domain.Page;
import org.springframework.data.domain.Pageable;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;

import java.util.List;
import java.util.Optional;
import java.util.Set;

@Repository
public interface AppParamDao extends CrudRepository<AppParam, Long>, JpaRepository<AppParam, Long> {
}