spring boot动态切换数据源

当数据量比较大的时候，我们就需要考虑读写分离了，也就是动态切换数据库连接,对指定的数据库进行操作。在spring中实现动态的切换无非就是利用AOP实现。我们可以使用mybatis-plus作者开发的插件dynamic-datasource-spring-boot-starter。
demo地址：https://github.com/songshijun1995/spring-boot-dynamic-demo

1. 新建项目引入依赖

<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>dynamic-datasource-spring-boot-starter</artifactId>
    <version>3.3.1</version>
</dependency>
<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>3.4.1</version>
</dependency>

2. 配置yml

server:
  port: 8081
  servlet:
    context-path: /

spring:
  application:
    name: spring-boot-dynamic-demo
  datasource:
    dynamic:
      primary: master #设置默认的数据源或者数据源组,默认值即为master
      strict: false #设置严格模式,默认false不启动. 启动后在未匹配到指定数据源时候会抛出异常,不启动则使用默认数据源.
      datasource:
        master:  #替换成自己的数据库连接
          url: jdbc:mysql://127.0.0.1:3306/dynamic1?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&failOverReadOnly=false&zeroDateTimeBehavior=convertToNull&serverTimezone=GMT%2B8&nullCatalogMeansCurrent=true&allowMultiQueries=true&rewriteBatchedStatements=true
          username: root
          password: 123456
          driver-class-name: com.mysql.cj.jdbc.Driver
        slave_1:
          url: jdbc:mysql://127.0.0.1:3306/dynamic2?useUnicode=true&characterEncoding=UTF-8&autoReconnect=true&failOverReadOnly=false&zeroDateTimeBehavior=convertToNull&serverTimezone=GMT%2B8&nullCatalogMeansCurrent=true&allowMultiQueries=true&rewriteBatchedStatements=true
          username: root
          password: 123456
          driver-class-name: com.mysql.cj.jdbc.Driver

mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.slf4j.Slf4jImpl
  global-config:
    db-config:
      logic-delete-value: 1
      logic-not-delete-value: 0
      logic-delete-field: deleted
  mapper-locations: classpath:/mapper/**.xml

logging:
  level:
    ROOT: INFO
    com.dynamic.dynamicdemo: DEBUG
  pattern:
    file: '%d{yyyy-MM-dd HH:mm:ss.SSS} %-5level [%thread] %logger{50} - %msg%n'
  file:
    name: ${logging.file.path}/${spring.application.name}.log
    path: /home/logs/${spring.application.name}
  logback:
    rollingpolicy:
      max-file-size: 10MB
      max-history: 30

3. mybatis-plus和swagger配置我就不多说了，demo里都有
4. 如何使用

package com.dynamic.dynamicdemo.service.impl;

import com.baomidou.dynamic.datasource.annotation.DS;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.core.toolkit.Wrappers;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.dynamic.dynamicdemo.dto.PageRequest;
import com.dynamic.dynamicdemo.dto.UserInfoRequest;
import com.dynamic.dynamicdemo.entities.BaseEntity;
import com.dynamic.dynamicdemo.entities.UserInfo;
import com.dynamic.dynamicdemo.mapper.UserInfoMapper;
import com.dynamic.dynamicdemo.service.UserInfoService;
import org.springframework.beans.BeanUtils;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

@Service
public class UserInfoServiceImpl extends ServiceImpl<UserInfoMapper, UserInfo> implements UserInfoService {

    @DS("master")
    @Transactional(rollbackFor = Exception.class)
    @Override
    public String saveUser(UserInfoRequest request) {
        UserInfo userInfo = new UserInfo();
        BeanUtils.copyProperties(request, userInfo);
        boolean save = save(userInfo);
        if (!save) {
            throw new RuntimeException("添加用户失败");
        }
        return "添加用户成功";
    }

    @DS("slave_1")
    @Override
    public IPage<UserInfo> pageUser(PageRequest request) {
        return page(new Page<>(request.getPageNum(), request.getPageSize()), Wrappers.<UserInfo>lambdaQuery().orderByDesc(BaseEntity::getCreateTime));
    }
}

在方法上或者类上加@DS("master")注解，来指定数据源

5. 更换为自己的数据库连接，以及建库，运行resources/sql目录下的sql文件
   然后启动项目访问http://127.0.0.1:8081/doc.html进行测试