如果在加上@Transactional注解之后报错，先查看程序是否为多数据源，之前专门有一章讲解springboot的多数据源实现。多数据源的情况下加事物注解，有可能会出现问题，以下是解决方案。

1.在配置数据源的同时，一定到在其中一个配置上加上@Primary注解，其他的不要加。

package com.wys.config;

import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.SqlSessionTemplate;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;
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.DriverManagerDataSource;

import javax.sql.DataSource;

/**
 * @program:  
 * @description: 数据库配置1
 * @author: wys
 * @create: 2019-12-03 16:20
 **/
@Configuration
@MapperScan(basePackages = "com.wys.mapper.**", sqlSessionFactoryRef = "oneSqlSessionFactory")
public class OneDataSourceConfig {
    @Value("${spring.datasource.one.driver-class-name}")
    String driverClass;
    @Value("${spring.datasource.one.url}")
    String url;
    @Value("${spring.datasource.one.username}")
    String userName;
    @Value("${spring.datasource.one.password}")
    String passWord;

    @Primary
    @Bean(name = "oneDataSource")
    @ConfigurationProperties("spring.datasource.one")
    public DataSource masterDataSource() {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName(driverClass);
        dataSource.setUrl(url);
        dataSource.setUsername(userName);
        dataSource.setPassword(passWord);
        return dataSource;
    }

    @Bean(name = "oneSqlSessionFactory")
    public SqlSessionFactory sqlSessionFactory(@Qualifier("oneDataSource") DataSource dataSource) throws Exception {
        SqlSessionFactoryBean sessionFactoryBean = new SqlSessionFactoryBean();
        sessionFactoryBean.setDataSource(dataSource);
        sessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver()
                .getResources("classpath:mybatis/mapper-postgre/*.xml"));
        
        return sessionFactoryBean.getObject();
    }
    @Bean(name = "oneSqlSessionFactory")
    public SqlSessionTemplate sqlSessionFactoryTemplate(@Qualifier("oneSqlSessionFactory")SqlSessionFactory sqlSessionFactory ) throws Exception {
        return new SqlSessionTemplate(sqlSessionFactory);
    }
}

2.一定要在需要使用事物注解的数据源配置里，加上创建事务管理器

package com.wys.config;

import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionFactoryBean;
import org.mybatis.spring.SqlSessionTemplate;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.autoconfigure.jdbc.DataSourceBuilder;
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.DriverManagerDataSource;

import javax.sql.DataSource;

/**
 * @program:  
 * @description: 数据库配置1
 * @author: wys
 * @create: 2019-12-03 16:20
 **/
@Configuration
@MapperScan(basePackages = "com.wys.mapper.**", sqlSessionFactoryRef = "oneSqlSessionFactory")
public class OneDataSourceConfig {
    @Value("${spring.datasource.one.driver-class-name}")
    String driverClass;
    @Value("${spring.datasource.one.url}")
    String url;
    @Value("${spring.datasource.one.username}")
    String userName;
    @Value("${spring.datasource.one.password}")
    String passWord;

    @Primary
    @Bean(name = "oneDataSource")
    @ConfigurationProperties("spring.datasource.one")
    public DataSource masterDataSource() {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName(driverClass);
        dataSource.setUrl(url);
        dataSource.setUsername(userName);
        dataSource.setPassword(passWord);
        return dataSource;
    }

    @Bean(name = "oneSqlSessionFactory")
    public SqlSessionFactory sqlSessionFactory(@Qualifier("oneDataSource") DataSource dataSource) throws Exception {
        SqlSessionFactoryBean sessionFactoryBean = new SqlSessionFactoryBean();
        sessionFactoryBean.setDataSource(dataSource);
        sessionFactoryBean.setMapperLocations(new PathMatchingResourcePatternResolver()
                .getResources("classpath:mybatis/mapper-postgre/*.xml"));
        
        return sessionFactoryBean.getObject();
    }
    /////////////////////
 // 创建事务管理器1
    @Bean(name = "oneManager1")
    public PlatformTransactionManager txManager(@Qualifier("oneDataSource") DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }
/////////////////////////
    @Bean(name = "oneSqlSessionFactory")
    public SqlSessionTemplate sqlSessionFactoryTemplate(@Qualifier("oneSqlSessionFactory")SqlSessionFactory sqlSessionFactory ) throws Exception {
        return new SqlSessionTemplate(sqlSessionFactory);
    }
}

在需要加注解的地方加上transactionManager 配置即可。

@Transactional(transactionManager ="oneManager1",rollbackFor=Exception.class)