由于服务没有做微服务部署，需要在后台管理系统访问其他服务的库，所以需要用到动态数据源切换

引入依赖

mybatis-plus动态数据源依赖

<dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>dynamic-datasource-spring-boot-starter</artifactId>
            <version>3.5.1</version>
        </dependency>

更改配置

spring:
  application:
    name: appName
  datasource:
    dynamic:
      # 指定默认数据源
      primary: aaaa1
      strict: false
      datasource:
        # 配置第一个数据源
        aaaa1:
          driverClassName: com.mysql.cj.jdbc.Driver
          url: jdbc:mysql://host:3306/xxx?characterEncoding=utf8&connectTimeout=1000&socketTimeout=3000&autoReconnect=true&useUnicode=true&useSSL=false&serverTimezone=Asia/Shanghai&rewriteBatchedStatements=true
          username: username
          password: password
        # 配置第二个数据源 
        aaaa2:
          driverClassName: com.mysql.cj.jdbc.Driver
          url: jdbc:mysql://host:3306/xxx?characterEncoding=utf8&connectTimeout=1000&socketTimeout=3000&autoReconnect=true&useUnicode=true&useSSL=false&serverTimezone=Asia/Shanghai&rewriteBatchedStatements=true
          username: username
          password: password

    druid:
      # 初始连接数
      initialSize: 5
      # 最小连接池数量
      minIdle: 10
      # 最大连接池数量
      maxActive: 20
      # 配置获取连接等待超时的时间
      maxWait: 60000
      # 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒
      timeBetweenEvictionRunsMillis: 60000
      # 配置一个连接在池中最小生存的时间，单位是毫秒
      minEvictableIdleTimeMillis: 300000
      # 配置一个连接在池中最大生存的时间，单位是毫秒
      maxEvictableIdleTimeMillis: 900000
      # 配置检测连接是否有效
      validationQuery: SELECT 1 FROM DUAL
      testWhileIdle: true
      testOnBorrow: false
      testOnReturn: false
      webStatFilter:
        enabled: true
      statViewServlet:
        enabled: true
        # 设置白名单，不填则允许所有访问
        allow:
        url-pattern: /druid/*
        # 控制台管理用户名和密码
      #        login-username: login-username
      #        login-password: login-password
      filter:
        stat:
          enabled: true
          # 慢SQL记录
          log-slow-sql: true
          slow-sql-millis: 1000
          merge-sql: true
        wall:
          config:
            multi-statement-allow: true

配置类

package com.ruoyi.framework.config;

import com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean;
import com.ruoyi.common.utils.StringUtils;
import org.apache.ibatis.io.VFS;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.boot.autoconfigure.SpringBootVFS;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.env.Environment;
import org.springframework.core.io.DefaultResourceLoader;
import org.springframework.core.io.Resource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternResolver;
import org.springframework.core.type.classreading.CachingMetadataReaderFactory;
import org.springframework.core.type.classreading.MetadataReader;
import org.springframework.core.type.classreading.MetadataReaderFactory;
import org.springframework.util.ClassUtils;

import javax.sql.DataSource;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;

/**
 * Mybatis支持*匹配扫描包
 *
 * @author ruoyi
 */
@Configuration
public class MyBatisConfig {
    @Autowired
    private Environment env;

    static final String DEFAULT_RESOURCE_PATTERN = "**/*.class";

    public static String setTypeAliasesPackage(String typeAliasesPackage) {
        ResourcePatternResolver resolver = (ResourcePatternResolver) new PathMatchingResourcePatternResolver();
        MetadataReaderFactory metadataReaderFactory = new CachingMetadataReaderFactory(resolver);
        List<String> allResult = new ArrayList<String>();
        try {
            for (String aliasesPackage : typeAliasesPackage.split(",")) {
                List<String> result = new ArrayList<String>();
                aliasesPackage = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX
                        + ClassUtils.convertClassNameToResourcePath(aliasesPackage.trim()) + "/" + DEFAULT_RESOURCE_PATTERN;
                Resource[] resources = resolver.getResources(aliasesPackage);
                if (resources != null && resources.length > 0) {
                    MetadataReader metadataReader = null;
                    for (Resource resource : resources) {
                        if (resource.isReadable()) {
                            metadataReader = metadataReaderFactory.getMetadataReader(resource);
                            try {
                                result.add(Class.forName(metadataReader.getClassMetadata().getClassName()).getPackage().getName());
                            } catch (ClassNotFoundException e) {
                                e.printStackTrace();
                            }
                        }
                    }
                }
                if (result.size() > 0) {
                    HashSet<String> hashResult = new HashSet<String>(result);
                    allResult.addAll(hashResult);
                }
            }
            if (allResult.size() > 0) {
                typeAliasesPackage = String.join(",", (String[]) allResult.toArray(new String[0]));
            } else {
                throw new RuntimeException("mybatis typeAliasesPackage 路径扫描错误,参数typeAliasesPackage:" + typeAliasesPackage + "未找到任何包");
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return typeAliasesPackage;
    }

    public Resource[] resolveMapperLocations(String[] mapperLocations) {
        ResourcePatternResolver resourceResolver = new PathMatchingResourcePatternResolver();
        List<Resource> resources = new ArrayList<Resource>();
        if (mapperLocations != null) {
            for (String mapperLocation : mapperLocations) {
                try {
                    Resource[] mappers = resourceResolver.getResources(mapperLocation);
                    resources.addAll(Arrays.asList(mappers));
                } catch (IOException e) {
                    // ignore
                }
            }
        }
        return resources.toArray(new Resource[resources.size()]);
    }

    @Bean
    public SqlSessionFactory sqlSessionFactory(DataSource dataSource) throws Exception {
        String typeAliasesPackage = env.getProperty("mybatis.typeAliasesPackage");
        String mapperLocations = env.getProperty("mybatis.mapperLocations");
        String configLocation = env.getProperty("mybatis.configLocation");
        typeAliasesPackage = setTypeAliasesPackage(typeAliasesPackage);
        VFS.addImplClass(SpringBootVFS.class);
        
        // 注意这里使用的是MybatisSqlSessionFactoryBean而不是SqlSessionFactoryBean
        final MybatisSqlSessionFactoryBean sessionFactory = new MybatisSqlSessionFactoryBean();
        sessionFactory.setDataSource(dataSource);
        sessionFactory.setTypeAliasesPackage(typeAliasesPackage);
        sessionFactory.setMapperLocations(resolveMapperLocations(StringUtils.split(mapperLocations, ",")));
        sessionFactory.setConfigLocation(new DefaultResourceLoader().getResource(configLocation));
        sessionFactory.setPlugins(new MybatisSqlLoggerInterceptor());
        return sessionFactory.getObject();
    }
}

添加注解

@DS注解我一般放在dao层，因为觉得这样更合理,如果使用了BaseMapper的批量处理以及接口操作，可以将注解放在service层解决找不到数据库问题

启动测试

问题：

动态数据源切换时效

当服务层接口添加事务注解，动态数据源切换就会失效，并且会使用默认的主数据源

批量处理接口异常

当dao层具体实现继承了BaseMapper并且服务处使用IService去实现，在批量处理时候就会出现异常，此时可以通过更改配置解决

使用 MybatisSqlSessionFactoryBean 替换 SqlSessionFactoryBean

参开原文：mybatis-plus框架TABLE_INFO_CACHE获取不到对应的TableInfo对象_error: can not execute. because can not find cache-CSDN博客

 另一种方式实现(未测试)：https://www.cnblogs.com/zhaww/p/12706941.html

根据Mybatis-plus配置动态数据源-从数据库获取源_mybatis plus 拦截器怎么获取当前数据库类型-CSDN博客

工作笔记，持续更新完善中