springboot+mybatisplus+mysql+druid双数据源动态切换（附代码）

1、首先引入各种jar，springboot、mybatisplus等，配置pom文件如下：

<?xml version="1.0" encoding="UTF-8"?>

    4.0.0
    com.hualife
    springboot
    1.0-SNAPSHOT
    
        org.springframework.boot
        spring-boot-starter-parent
        2.7.5
    
    
        1.8
        2.2.2
        1.4.5
        1.2.22
        2.11.0
        1.10
        8.0.30
        1.2.13
        3.5.2
    
    
        
            org.springframework.boot
            spring-boot-starter-test
            test
        
        
            org.springframework.boot
            spring-boot-starter-web
        
        
            com.github.pagehelper
            pagehelper-spring-boot-starter
            ${pagehelper.spring.boot.version}
        
        
            com.alibaba
            druid
            ${druid.version}
        
        
        
            mysql
            mysql-connector-java
            ${mysql.version}
        
        
            com.alibaba
            druid-spring-boot-starter
            1.2.4
            
                
                    druid
                    com.alibaba
                
            
        
        
            com.baomidou
            mybatis-plus-boot-starter
            ${mybatisplus.version}
            
                
                    com.baomidou
                    mybatis-plus-generator
                
                
                    jsqlparser
                    com.github.jsqlparser
                
                
                    mybatis
                    org.mybatis
                
            
        
        
            org.projectlombok
            lombok
            1.16.22
        
        
            org.apache.commons
            commons-lang3
        
        
            junit
            junit
            4.12
            test
        
    
    
        
            
                org.springframework.boot
                spring-boot-maven-plugin
                2.7.5
            
        
    

2、在yml中配置数据源信息如下（可多配置一些数据库连接池信息，自行百度吧有很多可以借鉴）：

server:
  port: 8080
spring:
  datasource:
    dynamic:
      datasource:
        master:
          #MySQL配置
          driver-class-name: com.mysql.cj.jdbc.Driver
          url: jdbc:mysql://localhost:3306/DB1?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai&nullCatalogMeansCurrent=true
          username: root
          password:
          initial-size: 2
          max-active: 20
          min-idle: 1
        slave:
          #MySQL配置
          driver-class-name: com.mysql.cj.jdbc.Driver
          url: jdbc:mysql://localhost:3306/DB2?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai&nullCatalogMeansCurrent=true
          username: root
          password:
          initial-size: 2
          max-active: 20
          min-idle: 1
mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  mapper-locations: classpath:mapper/**/*.xml

3、建数据库，建表，并且生成对应的Java实体及mapper及xml等（可使用开源版人人代码生成器）。

4、搭建springboot项目，项目结构如下图（除了config以外，其他的包应该都知道是啥）：

项目结构图

5、在config目录下创建Java类，CurrDataSource.java（注解类，可用于项目中区分数据源），DataSourceAspect.java(切面类，根据切面选择不同的数据源)，DataSourceFactory.java（数据源工厂，包含数据库连接池信息），DataSourceProperties.java（数据源信息封装的实体类），DBTypeName.java（数据源名称常量），DynamicContextHolder.java（数据源上下文切换用的，实际是队列），
DynamicDataSourceProperties.java(双数据源信息对应的map，具体看下文中的代码吧)，MyDynamicDataSourceConfig.java（动态数据源配置类），MyRoutingDataSource.java(数据源路由类)

6、数据源切换的注解：

import java.lang.annotation.*;
/**
 * 多数据源注解
 * 自己项目中添加
 */
@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
public @interface CurrDataSource {
    String value() default "master";
}

7、aop切面类：

import lombok.extern.slf4j.Slf4j;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.core.annotation.Order;
import org.springframework.stereotype.Component;
import java.lang.reflect.Method;
/**
 * 多数据源，切面处理类
 */
@Aspect
@Component
@Order(Ordered.HIGHEST_PRECEDENCE)
@Slf4j
public class DataSourceAspect {

    @Pointcut("@annotation(com.hualife.modules.config.CurrDataSource) "  //方法包含注解
            +"|| @within(com.hualife.modules.config.CurrDataSource)"    //类包含注解
            +"|| within(com.baomidou.mybatisplus.core.mapper.BaseMapper+)")
  // 切BaseMapper及其子类，因为在mapper加注解但调用父类的方法切不到，故加了within，这样就可以切到父类了
  //其实只要within表达式就行，因为不管是service的impl还是mapper最终调的都是mapper的方法
  public void dSPointCut() {
    }

    @Around("dSPointCut()")
    public Object around(ProceedingJoinPoint point) throws Throwable {
        MethodSignature signature = (MethodSignature) point.getSignature();
        Class targetClass = point.getTarget().getClass();
        Method method = signature.getMethod();
        log.info("执行数据库操作的类是：{},函数是：{}", targetClass.getName(), method.getName());
//        CurrDataSource targetDataSource = (CurrDataSource) targetClass.getAnnotation(CurrDataSource.class);
        CurrDataSource targetDataSource = AnnotationUtils.findAnnotation(targetClass, CurrDataSource.class);//获取目标类上注解
        CurrDataSource methodDataSource = method.getAnnotation(CurrDataSource.class);//获取目标函数上注解
        if (targetDataSource != null || methodDataSource != null) {
            log.info(targetDataSource + "===========" + methodDataSource);
            String value;
            if (methodDataSource != null) {
                value = methodDataSource.value();
            } else {
                value = targetDataSource.value();
            }
            DynamicContextHolder.push(value);
        } else {
            log.info("执行数据库操作的类及其函数上没有@CurrDataSource，而这个执行数据库操作的函数属于BaseMapper及其子类下的函数，故调用master");
            DynamicContextHolder.push(DBTypeName.MASTER);
        }
        try {
            return point.proceed();
        } finally {
            DynamicContextHolder.poll();
            log.info("clean datasource");
        }
    }
}

8、数据源工厂：

import com.alibaba.druid.pool.DruidDataSource;
import java.sql.SQLException;
/**
 * DruidDataSource
 */
public class DataSourceFactory {
    public static DruidDataSource buildDruidDataSource(DataSourceProperties properties) {
        DruidDataSource druidDataSource = new DruidDataSource();
        druidDataSource.setDriverClassName(properties.getDriverClassName());
        druidDataSource.setUrl(properties.getUrl());
        druidDataSource.setUsername(properties.getUsername());
        druidDataSource.setPassword(properties.getPassword());

        druidDataSource.setInitialSize(properties.getInitialSize());
        druidDataSource.setMaxActive(properties.getMaxActive());
        druidDataSource.setMinIdle(properties.getMinIdle());
        druidDataSource.setMaxWait(properties.getMaxWait());
        druidDataSource.setTimeBetweenEvictionRunsMillis(properties.getTimeBetweenEvictionRunsMillis());
        druidDataSource.setMinEvictableIdleTimeMillis(properties.getMinEvictableIdleTimeMillis());
        druidDataSource.setMaxEvictableIdleTimeMillis(properties.getMaxEvictableIdleTimeMillis());
        druidDataSource.setValidationQuery(properties.getValidationQuery());
        druidDataSource.setValidationQueryTimeout(properties.getValidationQueryTimeout());
        druidDataSource.setTestOnBorrow(properties.isTestOnBorrow());
        druidDataSource.setTestOnReturn(properties.isTestOnReturn());
        druidDataSource.setPoolPreparedStatements(properties.isPoolPreparedStatements());
        druidDataSource.setMaxOpenPreparedStatements(properties.getMaxOpenPreparedStatements());
        druidDataSource.setSharePreparedStatements(properties.isSharePreparedStatements());
        try {
            // druidDataSource.setFilters(properties.getFilters());
            druidDataSource.init();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return druidDataSource;
    }
}

9、多数据源属性类：

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
/**
 * 多数据源属性，yml
 */
@Data
@AllArgsConstructor
@NoArgsConstructor
public class DataSourceProperties {
    private String driverClassName;
    private String url;
    private String username;
    private String password;
    /**
     * Druid默认参数
     */
    private int initialSize = 2;
    private int maxActive = 10;
    private int minIdle = -1;
    private long maxWait = 60 * 1000L;
    private long timeBetweenEvictionRunsMillis = 60 * 1000L;
    private long minEvictableIdleTimeMillis = 1000L * 60L * 30L;
    private long maxEvictableIdleTimeMillis = 1000L * 60L * 60L * 7;
    private String validationQuery = "select 1";
    private int validationQueryTimeout = -1;
    private boolean testOnBorrow = false;
    private boolean testOnReturn = false;
    private boolean testWhileIdle = true;
    private boolean poolPreparedStatements = false;
    private int maxOpenPreparedStatements = -1;
    private boolean sharePreparedStatements = false;
    private String filters = "stat,wall";
}

10、数据库名字常量：

/**
 * 数据库名字常量
 */
public class DBTypeName {
    public static final String MASTER = "master";
    public static final String SLAVE = "slave";
}

11、多数据源上下文 ，用来放置数据源名字：

import java.util.ArrayDeque;
import java.util.Deque;
/**
 * 多数据源上下文
 * 用来放置数据源
 */
public class DynamicContextHolder {
    private static final ThreadLocal> HOLDER = new ThreadLocal>() {
        @Override
        protected Deque initialValue() {
            return new ArrayDeque();
        }
    };
    /**
     * 获得当前线程数据源
     * @return 数据源名称
     */
    public static String peek() {
        return HOLDER.get().peek();
    }

    /**
     * 设置当前线程数据源
     * @param dataSource 数据源名称
     */
    public static void push(String dataSource) {
        HOLDER.get().push(dataSource);
    }
    /**
     * 清空当前线程数据源
     */
    public static void poll() {
        Deque deque = HOLDER.get();
        deque.poll();
        if (deque.isEmpty()) {
            HOLDER.remove();
        }
    }
}

12、多数据源属性类（把yml中多数据源信息对应成map）：

import org.springframework.boot.context.properties.ConfigurationProperties;
import java.util.LinkedHashMap;
import java.util.Map;
/**
 * 多数据源属性
 */
@ConfigurationProperties(prefix = "spring.datasource.dynamic")
public class DynamicDataSourceProperties {
    private Map datasource = new LinkedHashMap<>();
    public Map getDatasource() {
        return datasource;
    }
    public void setDatasource(Map datasource) {
        this.datasource = datasource;
    }
}

13、多数据源动态切换配置类（整合了druid的数据监控）：

import com.alibaba.druid.filter.stat.StatFilter;
import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.support.http.StatViewServlet;
import com.baomidou.mybatisplus.core.MybatisConfiguration;
import com.baomidou.mybatisplus.core.MybatisXMLLanguageDriver;
import com.alibaba.druid.support.http.WebStatFilter;
import com.alibaba.druid.wall.WallConfig;
import com.alibaba.druid.wall.WallFilter;
import com.baomidou.mybatisplus.extension.spring.MybatisSqlSessionFactoryBean;
import lombok.extern.slf4j.Slf4j;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.type.JdbcType;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.boot.web.servlet.ServletRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.Resource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternResolver;
import java.io.IOException;
import java.util.*;

/**
 * 配置多数据源
 */
@Slf4j
@Configuration
@EnableConfigurationProperties(DynamicDataSourceProperties.class)
public class DynamicDataSourceConfig {
    @Autowired
    private DynamicDataSourceProperties dynamicDataSourceProperties;

    @Bean
    public DynamicRoutingDataSource dynamicDataSource() {
        DynamicRoutingDataSource dynamicDataSource = new DynamicRoutingDataSource();
        Map dataSourcePropertiesMap = dynamicDataSourceProperties.getDatasource();
        Map targetDataSources = new HashMap<>(dataSourcePropertiesMap.size());
        dataSourcePropertiesMap.forEach((k, v) -> {
            DruidDataSource druidDataSource = DynamicDataSourceFactory.buildDruidDataSource(v);
            targetDataSources.put(k, druidDataSource);
            if (DBTypeName.MASTER.equals(k)) {
                dynamicDataSource.setDefaultTargetDataSource(druidDataSource);
            }
        });
        dynamicDataSource.setTargetDataSources(targetDataSources);
        return dynamicDataSource;
    }

//    @Bean
//    public GlobalConfig globalConfig(@Qualifier("sqlInjector") ISqlInjector sqlInjector) {
//        GlobalConfig globalConfig = new GlobalConfig();
//        globalConfig.setSqlInjector(sqlInjector);
//        globalConfig.setBanner(false);
//        globalConfig.setMetaObjectHandler(new MyMetaObjectHandler());//自己写自动填充处理类
//        return globalConfig;
//    }

    @Bean("sqlSessionFactory")
    public SqlSessionFactory sqlSessionFactory() throws Exception {
        MybatisSqlSessionFactoryBean sqlSessionFactory = new MybatisSqlSessionFactoryBean();
        sqlSessionFactory.setDataSource(dynamicDataSource());
        sqlSessionFactory.setMapperLocations(resolveMapperLocations());
        MybatisConfiguration configuration = new MybatisConfiguration();
        configuration.setDefaultScriptingLanguage(MybatisXMLLanguageDriver.class);
        configuration.setJdbcTypeForNull(JdbcType.NULL);
        configuration.setMapUnderscoreToCamelCase(true);
        configuration.setCacheEnabled(false);
        //configuration.setLogImpl(StdOutImpl.class);
        sqlSessionFactory.setConfiguration(configuration);
        //添加自定义sql注入接口，可以设置数据库字段自动填充
        //sqlSessionFactory.setGlobalConfig(globalConfig);
        return sqlSessionFactory.getObject();
    }

    public Resource[] resolveMapperLocations() {
        ResourcePatternResolver resourceResolver = new PathMatchingResourcePatternResolver();
        List mapperLocations = new ArrayList<>();
        mapperLocations.add("classpath*:com/hualife/*/inner/*/mapper/*.xml");//可加多个
        List resources = new ArrayList();
        for (String mapperLocation : mapperLocations) {
            try {
                Resource[] mappers = resourceResolver.getResources(mapperLocation);
                resources.addAll(Arrays.asList(mappers));
            } catch (IOException e) {
                e.printStackTrace();
                log.error(e.getMessage());
            }
        }
        return resources.toArray(new Resource[resources.size()]);
    }

    /**
     * druid访问配置，德鲁伊访问页面设置，可以看数据库连接池相关信息
     */
    @Bean
    public ServletRegistrationBean druidServlet() {
        ServletRegistrationBean servletRegistrationBean = new ServletRegistrationBean<>(new StatViewServlet(), "/druid/*");
        //控制台管理用户，加入下面2行 进入druid后台就需要登录
        servletRegistrationBean.addInitParameter("loginUsername", "admin");
        servletRegistrationBean.addInitParameter("loginPassword", "admin");
        return servletRegistrationBean;
    }

    @Bean
    public FilterRegistrationBean filterRegistrationBean() {
        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean<>();
        filterRegistrationBean.setFilter(new WebStatFilter());
        filterRegistrationBean.addUrlPatterns("/*");
        filterRegistrationBean.addInitParameter("exclusions", "*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*");
        filterRegistrationBean.addInitParameter("profileEnable", "true");
        return filterRegistrationBean;
    }

    @Bean
    public StatFilter statFilter() {
        StatFilter statFilter = new StatFilter();
        //slowSqlMillis用来配置SQL慢的标准，执行时间超过slowSqlMillis的就是慢。
        statFilter.setLogSlowSql(true);
        //SQL合并配置
        statFilter.setMergeSql(true);
        statFilter.setDbType("mysql");
        //slowSqlMillis的缺省值为3000，也就是3秒。
        statFilter.setSlowSqlMillis(3000);
        return statFilter;
    }

    @Bean
    public WallFilter wallFilter() {
        WallFilter wallFilter = new WallFilter();
        //允许执行多条SQL
        WallConfig config = new WallConfig();
        config.setMultiStatementAllow(true);
        wallFilter.setConfig(config);
        return wallFilter;
    }
}

14、多数据源路由：

import lombok.extern.slf4j.Slf4j;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;
/**
 * 多数据源
 */
@Slf4j
public class MyRoutingDataSource extends AbstractRoutingDataSource {
    @Override
    protected Object determineCurrentLookupKey() {
        String dataSource = DynamicContextHolder.peek();
        log.info("使用数据源：{}", dataSource);
        return dataSource;
    }
}

15、多数据源路由理解：参考下图（借用别人的图）
https://www.cnblogs.com/zzsuje/p/15465431.html

16、备注

项目搭建及部分代码参考人人代码生成器