SpringMvc整合Mybatis并使用声明式事务

（1）、引入相关依赖

     <dependency>
       <groupId>com.alibaba</groupId>
       <artifactId>druid</artifactId>
       <version>1.1.12</version>
     </dependency>

     <dependency>
       <groupId>mysql</groupId>
       <artifactId>mysql-connector-java</artifactId>
       <version>8.0.13</version>
     </dependency>

     <dependency>
       <groupId>org.springframework</groupId>
       <artifactId>spring-orm</artifactId>
       <version>4.3.22.RELEASE</version>
     </dependency>

     <dependency>
       <groupId>org.mybatis</groupId>
       <artifactId>mybatis-spring</artifactId>
       <version>2.0.0</version>
     </dependency>
     <dependency>
       <groupId>org.mybatis</groupId>
       <artifactId>mybatis</artifactId>
       <version>3.5.0</version>
     </dependency>

（2）、编写Mybatis配置类

 package cn.coreqi.config;

 import com.alibaba.druid.pool.DruidDataSource;
 import org.mybatis.spring.SqlSessionFactoryBean;
 import org.mybatis.spring.annotation.MapperScan;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.jdbc.datasource.DataSourceTransactionManager;
 import org.springframework.transaction.annotation.EnableTransactionManagement;

 import javax.sql.DataSource;

 @EnableTransactionManagement    //启动事务管理器
 @Configuration
 @MapperScan(value = "cn.coreqi.mapper") //扫描Mapper文件
 public class MybatisConfig {
     @Bean
     public DataSource dataSource(){
         DruidDataSource ds = new DruidDataSource();
         ds.setDriverClassName("com.mysql.jdbc.Driver");
         ds.setUrl("jdbc:mysql://localhost:3306/mybatisdemo?serverTimezone=UTC");
         ds.setUsername("root");
         ds.setPassword("123456");
         return ds;
     }

     //注册Mybatis SqlSessionFactory
     @Bean
     public SqlSessionFactoryBean sqlSessionFactory(DataSource dataSource){
         SqlSessionFactoryBean sqlSessionFactory = new SqlSessionFactoryBean();
         sqlSessionFactory.setDataSource(dataSource);
         return sqlSessionFactory;
     }

     //注册事务管理器
     @Bean
     public DataSourceTransactionManager transactionManager(DataSource dataSource){
         DataSourceTransactionManager transactionManager = new DataSourceTransactionManager();
         transactionManager.setDataSource(dataSource);
         return transactionManager;
     }
 }

（3）、编写Mapper文件

 package cn.coreqi.mapper;

 import cn.coreqi.entities.User;
 import org.apache.ibatis.annotations.*;

 @Mapper
 public interface UserMapper{
     @Select("select * from users where Id = #{id}")
     public User getUserById(Integer id);
     @Insert("insert into users(UserName,PassWord,Enabled) values(#{UserName},#{PassWord},#{Enabled})")
     @Options(useGeneratedKeys = true,keyProperty = "Id")
     public int addUser(User user);
     @Update("update users set UserName = #{UserName},PassWord = #{PassWord},Enabled = #{Enabled} where Id = #{Id}")
     public int modifyUser(User user);
     @Delete("delete from users where Id = #{id}")
     public void delById(Integer id);
 }

（4）、编写Service文件

 package cn.coreqi.service;

 import cn.coreqi.entities.User;
 import cn.coreqi.mapper.UserMapper;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Isolation;
 import org.springframework.transaction.annotation.Propagation;
 import org.springframework.transaction.annotation.Transactional;

 import java.io.IOException;
 import java.sql.SQLException;

 @Service
 public class UserService {
     @Autowired
     private UserMapper userMapper;

     @Transactional(readOnly = true)
     public User getUserById(Integer id){
         return userMapper.getUserById(id);
     }

     @Transactional
     public User insertUser(User user){
         userMapper.addUser(user);
         return user;
     }

     //@Transactional属性
     //  1.propagation   指定当前事务的传播行为，共7种，常用的有REQUIRES_NEW和REQUIRED
     //  2.isolation     指定当前事务的隔离级别，共5种，常用的有READ_COMMITTED，*事务的隔离级别要得到底层数据库的支持，而不是应用程序和框架的支持
     //  3.rollbackFor&noRollbackFor   指定当前事务的回滚属性，rollbackFor指定遇到那些异常进行回滚，noRollbackFor指定遇到那些异常不进行回滚。*如果不指定这两个属性的默认情况下
     //                                Spring的声明式事务对所有的运行时异常（RuntimeException）和Error类型的异常进行回滚。
     //  4.readOnly      指定当前事务是否只读，true表示这个事务只读取数据而不对数据做修改，这样可以帮助数据库引擎优化事务
     //  5.timeout       指定当前事务可以保持多久，防止长期运行事务占用资源，单位秒。
     @Transactional(propagation = Propagation.REQUIRES_NEW,isolation = Isolation.READ_COMMITTED,
             rollbackFor = {IOException.class, SQLException.class},noRollbackFor = {ArithmeticException.class},
     readOnly = false,timeout = 30)
     public User modifyUser(User user){
         userMapper.modifyUser(user);
         return user;
     }

     @Transactional
     public void delById(Integer id){
         userMapper.delById(id);

     }
 }