mybatis-plus动态数据源切换不生效的问题解决

一、问题描述
在我们项目中，既要连接Mysql，又要连接TDEngine（taos），正确配置后也无法动态切换数据源执行sql
二、环境
1.依赖

        <dependency>            <groupId>com.taosdata.jdbcgroupId>            <artifactId>taos-jdbcdriverartifactId>            <version>3.0.0version>        dependency>           <dependency>            <groupId>com.baomidougroupId>            <artifactId>dynamic-datasource-spring-boot-starterartifactId>            <version>3.3.2version>        dependency>

配置

spring:  datasource:    dynamic:      strict: true      primary: mysql      datasource:        mysql:          driver-class-name: com.mysql.cj.jdbc.Driver          url: jdbc:mysql://192.xxx.xxx.xxx:3306/db_iot?useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=Asia/Shanghai          username: root          passWord: 123456        tdengine:          driver-class-name: com.taosdata.jdbc.TSDBDriver          url: jdbc:TAOS://192.xxx.xxx.xxx:6030/iot_data?timezone=UTC-8&charset=UTF-8&locale=en_US.UTF-8          username: root          password: taosdata        mysql1:          driver-class-name: com.mysql.cj.jdbc.Driver          url: jdbc:mysql://192.xxx.xxx.xxx:3306/db_portal?useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=Asia/Shanghai          username: root          password: 123456

三、解决方法
直接上代码，最后会有问题分析，因为涉及到源码，这里暂时不讲
这里的dynamicRoutingDataSource()不能有DynamicDataSourceAutoConfiguration里的那样命名和返回值，那样在注入时就会因为其他数据源的注入导致无法注入动态数据源，需要细化到具体的类型

package com.xxx.project.iotconf.configs;import com.baomidou.dynamic.datasource.DynamicRoutingDataSource;import com.baomidou.dynamic.datasource.provider.DynamicDataSourceProvider;import com.baomidou.dynamic.datasource.provider.YmlDynamicDataSourceProvider;import com.baomidou.dynamic.datasource.spring.boot.autoconfigure.DataSourceProperty;import com.baomidou.dynamic.datasource.spring.boot.autoconfigure.DynamicDataSourceProperties;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.context.annotation.Primary;import javax.sql.DataSource;import java.util.Map;@Configurationpublic class TDEngineConfig {    @Autowired    private DynamicDataSourceProperties properties;    @Bean    @ConditionalOnMissingBean    @Primary    public DynamicDataSourceProvider dynamicDataSourceProvider() {        Map<String, DataSourceProperty> datasourceMap = this.properties.getDatasource();        return new YmlDynamicDataSourceProvider(datasourceMap);    }    @Bean    @ConditionalOnMissingBean    public DynamicRoutingDataSource dynamicRoutingDataSource(DynamicDataSourceProvider dynamicDataSourceProvider) {        DynamicRoutingDataSource dynamicRoutingDataSource = new DynamicRoutingDataSource();        dynamicRoutingDataSource.setPrimary(this.properties.getPrimary());        dynamicRoutingDataSource.setStrict(this.properties.getStrict());        dynamicRoutingDataSource.setStrategy(this.properties.getStrategy());        dynamicRoutingDataSource.setProvider(dynamicDataSourceProvider);        dynamicRoutingDataSource.setP6spy(this.properties.getP6spy());        dynamicRoutingDataSource.setSeata(this.properties.getSeata());        Map<String, DataSource> dataSourceMap = dynamicDataSourceProvider.loadDataSources();        for (String key : dataSourceMap.keySet()) {            dynamicRoutingDataSource.aDDDataSource(key, dataSourceMap.get(key));        }        return dynamicRoutingDataSource;    }}

四、测试
放入TAOS创建超表的SQL，由JdbcTemplate去执行，执行成功

package com.xxx.project.iot.pulsar.handler;import com.baomidou.dynamic.datasource.annotation.DS;import com.shandy.project.api.basic.dto.SDevice;import com.shandy.project.api.basic.dto.Tuple2;import com.shandy.project.iot.pulsar.utils.ReflectUtils;import lombok.extern.slf4j.Slf4j;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.jdbc.core.JdbcTemplate;import org.springframework.stereotype.Service;import javax.annotation.PostConstruct;import java.util.List;import java.util.Map;@Service@Slf4jpublic class DataHandler implements DsHandler{    @Autowired    private JdbcTemplate jdbcTemplate;    @PostConstruct    public void init() {    }        @DS(value = "tdengine")    public void execute(String sql) {        jdbcTemplate.execute(sql);        log.info(sql);    }        @DS(value = "tdengine")    public List<Map<String, Object>> query(String sql, Object[] args) {        log.info(String.fORMat("%s，params is {%s}", sql, args));        return jdbcTemplate.queryForList(sql, args);    }        @DS(value = "tdengine")    public void batchInsertDevice(List<SDevice> devices, String table) {        String[] sqls = null;        jdbcTemplate.batchUpdate(sqls);        log.info(sqls.toString());    }        @DS(value = "tdengine")    public void insertDevice(SDevice device, Object MQttObj) {        Tuple2<String, List<Object>> t2 = ReflectUtils.getInsSql(mQttObj.getClass(), device);        List<Object> list = t2.getField(1);        String sql = t2.getField(0);        jdbcTemplate.update(sql, list.toArray());        log.info(sql);    }}

五、问题分析
1.一开始执行时，总是报错误的SQL语句，要我检查Mysql的版本，所以从这个提示来看，是没有动态切换到我们的taos数据库的。
什么原因呢？我们看com.baomidou.dynamic.datasource.spring.boot.autoconfigure.DynamicDataSourceAutoConfiguration类的方法

   @Bean    @ConditionalOnMissingBean    public DataSource dataSource(DynamicDataSourceProvider dynamicDataSourceProvider) {        DynamicRoutingDataSource dataSource = new DynamicRoutingDataSource();        dataSource.setPrimary(this.properties.getPrimary());        dataSource.setStrict(this.properties.getStrict());        dataSource.setStrategy(this.properties.getStrategy());        dataSource.setProvider(dynamicDataSourceProvider);        dataSource.setP6spy(this.properties.getP6spy());        dataSource.setSeata(this.properties.getSeata());        return dataSource;    }

这里有个@ConditionalOnMissingBean注解，意思是当dataSource对象不存在时才会进行注入。
我发现我除了配置了动态数据源，也配置了druid数据源，在项目启动是肯定是会注入druid的DataSource对象的，那就导致我们的动态数据源的DataSource对象无法注入，可能这就是切换不了的原因。这里或许可以尝试把druid数据源去掉，但我没有往这个方向去深究。

spring.datasource.druid.db-type=mysqlspring.datasource.druid.driver-class-name=com.mysql.cj.jdbc.Driverspring.datasource.druid.url=jdbc:mysql://192.xxx.xxx.xxx:3306/db_iot?useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=Asia/Shanghaispring.datasource.druid.username=rootspring.datasource.druid.password=123456

既然没有注入DynamicRoutingDataSource对象，我自己就写了上文中的TDEngineConfig去注入，其中方法和DynamicDataSourceAutoConfiguration类似，只是稍微做改造。

在最开始我原封不动的把DynamicDataSourceAutoConfiguration方法抄下来，在执行SQL时报：dynamic-datasource could not find a datasource named tdengine
异常来自于在DynamicRoutingDataSource的getDataSource（）方法

public DataSource getDataSource(String ds) {        if (StringUtils.isEmpty(ds)) {            return this.determinePrimaryDataSource();        } else if (!this.groupDataSources.isEmpty() && this.groupDataSources.containsKey(ds)) {            log.debug("dynamic-datasource switch to the datasource named [{}]", ds);            return ((GroupDataSource)this.groupDataSources.get(ds)).determineDataSource();        } else if (this.dataSourceMap.containsKey(ds)) {            log.debug("dynamic-datasource switch to the datasource named [{}]", ds);            return (DataSource)this.dataSourceMap.get(ds);        } else if (this.strict) {            throw new CannotFindDataSourceException("dynamic-datasource could not find a datasource named" + ds);        } else {            return this.determinePrimaryDataSource();        }    }

从这里发现，DynamicRoutingDataSource的dataSourceMap是空的，那自然报错，但是DynamicDataSourceProperties的dataSourceMap并不是空的，所以配置并没有出错，只是项目在启动时没有填充DynamicRoutingDataSource的dataSourceMap，那不妨我们自己来完成这件事情。
在TDEngineConfig的dynamicDataSourceProvider()方法中将properties的datasourceMap封装到YmlDynamicDataSourceProvider中，再看它的loadDataSources()，不就可以获取到Map类型的一个对象吗，我们把这个想办法赋值给DynamicRoutingDataSource的dataSourceMap

   public Map<String, DataSource> loadDataSources() {        return this.createDataSourceMap(this.dataSourcePropertiesMap);    }

所以在TDEngineConfig的dynamicRoutingDataSource方法中通过如下代码获取到dataSourceMap

 Map<String, DataSource> dataSourceMap = dynamicDataSourceProvider.loadDataSources();

再通过下面代码就将DynamicRoutingDataSource的dataSourceMap填充好了

 for (String key : dataSourceMap.keySet()) {            dynamicRoutingDataSource.addDataSource(key, dataSourceMap.get(key));        }

此时完成DynamicRoutingDataSource的注入。
这样再调用SQL时，就可以获取@DS注解的value值，充当key去dataSourceMap里找到对应的数据源进行切换

来源地址：https://blog.csdn.net/qq_46552655/article/details/128418714