SpringBoot实现多数据源（五）【多数据源事务控制】

素颜马尾好姑娘i 2024-03-31 12:27 115阅读 0赞

上一篇文章《[SpringBoot实现多数据源（四）【集成多个 Mybatis 框架】][SpringBoot_ Mybatis]》

#### 五、多数据源事务控制 ####

--------------------

在多数据源下，由于涉及到数据库的多个读写。一旦发生异常可能会导致数据不一致的情况，在这种情况希望使用事务进行回退

但是 Spring 的声明式事务在一次请求线程中只能使用一个数据源进行控制

对于多源数据库来讲：

1.  单一事务管理器（TransactionManager）无法切换数据源，需要配置多个 **TransactionManager**
2.  @Transaction 是无法管理多个数据源的。如果想真正实现多源数据库事务的控制，肯定需要分布式事务。这里讲解多源数据库事务控制的一种变通方式

> 一个方法开启2个事务

1）编程式事务

1.  修改**读写**Mybatis的配置类，为其添加事务管理者以及由Spring提供的事务模板

*  **RMybatisConfiguration**

package com.vinjcent.config.mybatis;
    
    import com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceBuilder;
    import org.apache.ibatis.logging.stdout.StdOutImpl;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.mybatis.spring.SqlSessionFactoryBean;
    import org.mybatis.spring.annotation.MapperScan;
    import org.springframework.beans.factory.annotation.Qualifier;
    import org.springframework.boot.context.properties.ConfigurationProperties;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.context.annotation.Primary;
    import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
    import org.springframework.jdbc.datasource.DataSourceTransactionManager;
    import org.springframework.transaction.support.TransactionTemplate;
    
    import javax.sql.DataSource;
    
    
    /**
     * 读数据源配置
     * 1. 指定扫描mapper接口包
     * 2. 指定使用rSqlSessionFactory是哪个
     */
    @Configuration
    @MapperScan(basePackages = "com.vinjcent.mapper.read", sqlSessionFactoryRef = "rSqlSessionFactory")
    public class RMybatisConfiguration {
        
    
    
        // readDataSource(读数据源)
        @Bean(name = "readDatasource")
        @ConfigurationProperties(prefix = "spring.datasource.read")
        public DataSource readDatasource() {
        
            // 底层会自动拿到spring.datasource中的配置,创建一个DruidDataSource
            return DruidDataSourceBuilder.create().build();
        }
    
        // SqlSessionFactory(ibatis会话工厂)
        @Bean
        @Primary
        public SqlSessionFactory rSqlSessionFactory(@Qualifier("readDatasource") DataSource dataSource) throws Exception {
        
            final SqlSessionFactoryBean sqlSessionFactory = new SqlSessionFactoryBean();
            sqlSessionFactory.setDataSource(dataSource);
            sqlSessionFactory.setMapperLocations(new PathMatchingResourcePatternResolver()
                    .getResources("classpath:com/vinjcent/mapper/read/*.xml"));
            /*主库设置sql控制台打印*/
            org.apache.ibatis.session.Configuration configuration = new org.apache.ibatis.session.Configuration();
            configuration.setLogImpl(StdOutImpl.class);
            sqlSessionFactory.setConfiguration(configuration);
            sqlSessionFactory.setTypeAliasesPackage("com.vinjcent.pojo");
            return sqlSessionFactory.getObject();
        }
    
        // TransactionManager(事务管理者)
        @Bean
        public DataSourceTransactionManager rTransactionManager() {
        
            DataSourceTransactionManager transactionManager = new DataSourceTransactionManager();
            transactionManager.setDataSource(readDatasource());
            return transactionManager;
        }
    
        // TransactionTemplate(事务模板)
        @Bean
        public TransactionTemplate rTransactionTemplate() {
        
            return new TransactionTemplate(rTransactionManager());
        }
    }

*  **WMybatisConfiguration**

package com.vinjcent.config.mybatis;
    
    import com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceBuilder;
    import org.apache.ibatis.logging.stdout.StdOutImpl;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.mybatis.spring.SqlSessionFactoryBean;
    import org.mybatis.spring.annotation.MapperScan;
    import org.springframework.beans.factory.annotation.Qualifier;
    import org.springframework.boot.context.properties.ConfigurationProperties;
    import org.springframework.context.annotation.Bean;
    import org.springframework.context.annotation.Configuration;
    import org.springframework.context.annotation.Primary;
    import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
    import org.springframework.jdbc.datasource.DataSourceTransactionManager;
    import org.springframework.transaction.support.TransactionTemplate;
    
    import javax.sql.DataSource;
    
    
    /**
     * 写数据源配置
     * 1. 指定扫描mapper接口包
     * 2. 指定使用wSqlSessionFactory是哪个
     */
    @Configuration
    @MapperScan(basePackages = "com.vinjcent.mapper.write", sqlSessionFactoryRef = "wSqlSessionFactory")
    public class WMybatisConfiguration {
        
    
    
        // writeDataSource(写数据源)
        @Bean(name = "writeDatasource")
        @ConfigurationProperties(prefix = "spring.datasource.write")
        public DataSource writeDatasource() {
        
            // 底层会自动拿到spring.datasource中的配置,创建一个DruidDataSource
            return DruidDataSourceBuilder.create().build();
        }
    
        // SqlSessionFactory(ibatis会话工厂)
        @Bean
        @Primary
        public SqlSessionFactory wSqlSessionFactory(@Qualifier("writeDatasource") DataSource dataSource) throws Exception {
        
            final SqlSessionFactoryBean sqlSessionFactory = new SqlSessionFactoryBean();
            sqlSessionFactory.setDataSource(dataSource);
            sqlSessionFactory.setMapperLocations(new PathMatchingResourcePatternResolver()
                    .getResources("classpath:com/vinjcent/mapper/write/*.xml"));
            /* 主库设置sql控制台打印 */
            org.apache.ibatis.session.Configuration configuration = new org.apache.ibatis.session.Configuration();
            configuration.setLogImpl(StdOutImpl.class);
            sqlSessionFactory.setConfiguration(configuration);
            sqlSessionFactory.setTypeAliasesPackage("com.vinjcent.pojo");
            return sqlSessionFactory.getObject();
        }
    
        // TransactionManager(事务管理者)
        @Bean
        @Primary
        public DataSourceTransactionManager wTransactionManager() {
        
            DataSourceTransactionManager transactionManager = new DataSourceTransactionManager();
            transactionManager.setDataSource(writeDatasource());
            return transactionManager;
        }
    
        // TransactionTemplate(事务模板)
        @Bean
        public TransactionTemplate wTransactionTemplate() {
        
            return new TransactionTemplate(wTransactionManager());
        }
    }

1.  修改Service层
    
     *  **PeopleServiceImpl**

package com.vinjcent.service.impl;
    
    import com.vinjcent.mapper.read.RPeopleMapper;
    import com.vinjcent.mapper.write.WPeopleMapper;
    import com.vinjcent.pojo.People;
    import com.vinjcent.service.PeopleService;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    import org.springframework.transaction.support.TransactionTemplate;
    
    import java.util.List;
    
    @Service
    public class PeopleServiceImpl implements PeopleService {
        
    
    
        // 读mapper
        private final RPeopleMapper rPeopleMapper;
    
        // 写mapper
        private final WPeopleMapper wPeopleMapper;
    
        // 读事务模板
        private final TransactionTemplate rTransactionTemplate;
    
        // 写事务模板
        private final TransactionTemplate wTransactionTemplate;
    
        @Autowired
        public PeopleServiceImpl(RPeopleMapper rPeopleMapper, WPeopleMapper wPeopleMapper, TransactionTemplate rTransactionTemplate, TransactionTemplate wTransactionTemplate) {
        
            this.rPeopleMapper = rPeopleMapper;
            this.wPeopleMapper = wPeopleMapper;
            this.rTransactionTemplate = rTransactionTemplate;
            this.wTransactionTemplate = wTransactionTemplate;
        }
    
    
        @Override
        public List<People> list() {
        
            return rPeopleMapper.list();
        }
    
        @Override
        public boolean save(People people) {
        
            return wPeopleMapper.save(people);
        }
    
    
        // 从库保存
        public boolean rSave(People people) {
        
            return rPeopleMapper.save(people);
        }
    
        // 主库保存
        public boolean wSave(People people) {
        
            return wPeopleMapper.save(people);
        }
    
        // 主从库保存
        @Override
        public void saveAll(People people) {
        
            // 写事务模板
            wTransactionTemplate.execute(wStatus -> {
        
                // 读事务模板
                rTransactionTemplate.execute(rStatus -> {
        
                    try {
        
                        rSave(people);
                        wSave(people);
                        // 模拟异常
                        int a = 1 /0;
                    } catch (Exception e) {
        
                        e.printStackTrace();
                        // 出现异常回滚"写"事务
                        wStatus.setRollbackOnly();
                        // 出现异常回滚"读"事务
                        rStatus.setRollbackOnly();
                        return false;
                    }
                    return true;
                });
                return true;
            });
    
        }
    
    
    }

1.  在Controller当中添加接口并测试
    
     *  **PeopleController**

package com.vinjcent.controller;
    
    import com.vinjcent.pojo.People;
    import com.vinjcent.service.PeopleService;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    import java.util.List;
    
    @RestController
    @RequestMapping("people")
    public class PeopleController {
        
    
    
        private final PeopleService peopleService;
    
        @Autowired
        public PeopleController(PeopleService peopleService) {
        
            this.peopleService = peopleService;
        }
    
    
        @GetMapping("/list")
        public List<People> getAllPeople() {
        
            //...
        }
    
        @GetMapping("/insert")
        public String addPeople() {
        
            //...
        }
    	
        // 添加位置
        @GetMapping("/save")
        public String addPeopleForWriteAndRead() {
        
            peopleService.saveAll(new People("ReadAndWrite"));
            return "读写库添加成功~";
        }
    
    }

1.  运行并测试接口

2）声明式事务

修改Service层

package com.vinjcent.service.impl;
    
    import com.vinjcent.mapper.read.RPeopleMapper;
    import com.vinjcent.mapper.write.WPeopleMapper;
    import com.vinjcent.pojo.People;
    import com.vinjcent.service.PeopleService;
    import org.springframework.aop.framework.AopContext;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    import org.springframework.transaction.annotation.Propagation;
    import org.springframework.transaction.annotation.Transactional;
    import org.springframework.transaction.support.TransactionTemplate;
    
    import java.util.List;
    
    @Service
    public class PeopleServiceImpl implements PeopleService {
        
    
    
        // 读mapper
        private final RPeopleMapper rPeopleMapper;
    
        // 写mapper
        private final WPeopleMapper wPeopleMapper;
    
        // 读事务模板
        private final TransactionTemplate rTransactionTemplate;
    
        // 写事务模板
        private final TransactionTemplate wTransactionTemplate;
    
        @Autowired
        public PeopleServiceImpl(RPeopleMapper rPeopleMapper, WPeopleMapper wPeopleMapper, TransactionTemplate rTransactionTemplate, TransactionTemplate wTransactionTemplate) {
        
            this.rPeopleMapper = rPeopleMapper;
            this.wPeopleMapper = wPeopleMapper;
            this.rTransactionTemplate = rTransactionTemplate;
            this.wTransactionTemplate = wTransactionTemplate;
        }
    
    
        @Override
        public List<People> list() {
        
            return rPeopleMapper.list();
        }
    
        @Override
        public boolean save(People people) {
        
            return wPeopleMapper.save(people);
        }
    
    
        // 从库保存
        public boolean rSave(People people) {
        
            return rPeopleMapper.save(people);
        }
    
        // 主库保存
        public boolean wSave(People people) {
        
            return wPeopleMapper.save(people);
        }
    
        // 主从库保存
        @Transactional("wTransactional")
        @Override
        public void saveAll(People people) {
        
            // 获取当前的service代理类对象,需要在主启动类开启@EnableAspectJAutoProxy(exposeProxy = true),暴露代理对象
            PeopleService peopleService = (PeopleService) AopContext.currentProxy();
            peopleService.saveAllR(people);
        }
        
        
        @Transactional(value = "rTransactional")
        @Override
        public void saveAllR(People people) {
        
            wSave(people);
            rSave(people);
            int a = 1 / 0;
        }
    }

下一篇文章《[SpringBoot实现多数据源（六）【dynamic-datasource 多数据源组件】][SpringBoot_dynamic-datasource]》

[SpringBoot_ Mybatis]: https://blog.csdn.net/Wei_Naijia/article/details/128069791
[SpringBoot_dynamic-datasource]: https://blog.csdn.net/Wei_Naijia/article/details/128069866