Spring声明式事务的实现

浅浅的花香味﹌ 2022-11-27 12:10 177阅读 0赞

### 目录 ###

*   *  1. 导入相关jar包
     *  2. 创建实体类User
     *  3. 编写UserMapper接口
     *  4. 编写UserMapper.xml配置文件
     *  5. 编写Spring配置文件applicationContext.xml
     *  6. 编写UserMapper接口实现类
     *  7. 编写测试类
     *  8. 运行查看结果
     *  9. 修改，增加声明式事务支持
     *   *  1. 开启Spring的事务处理功能
         *  2. 配置事务通知
         *  3. 结合AOP实现事务织入
     *  10. 再次测试

> **首先新建一个Spring-MyBatis程序**
> 
> **项目结构**：
> 
> ![image-20200815112250177][]

## 1. 导入相关jar包 ##

<dependencies>
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>4.13</version>
                <scope>test</scope>
            </dependency>
            <dependency>
                <groupId>org.mybatis</groupId>
                <artifactId>mybatis</artifactId>
                <version>3.5.5</version>
            </dependency>
            <dependency>
                <groupId>mysql</groupId>
                <artifactId>mysql-connector-java</artifactId>
                <version>8.0.21</version>
            </dependency>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-webmvc</artifactId>
                <version>5.2.8.RELEASE</version>
            </dependency>
            <dependency>
                <groupId>org.springframework</groupId>
                <artifactId>spring-jdbc</artifactId>
                <version>5.2.6.RELEASE</version>
            </dependency>
            <dependency>
                <groupId>org.aspectj</groupId>
                <artifactId>aspectjweaver</artifactId>
                <version>1.9.4</version>
            </dependency>
            <dependency>
                <groupId>org.mybatis</groupId>
                <artifactId>mybatis-spring</artifactId>
                <version>2.0.5</version>
            </dependency>
            <dependency>
                <groupId>org.projectlombok</groupId>
                <artifactId>lombok</artifactId>
                <version>1.18.12</version>
            </dependency>
        </dependencies>

## 2. 创建实体类User ##

**IDEA首先连接数据库**

这里的数据库表为：  
![image-20200815112204178][]  
**创建实体类User**

@Data
    @AllArgsConstructor
    @NoArgsConstructor
    public class User { 
        private int id;
        private String name;
        private String pwd;
    }

## 3. 编写UserMapper接口 ##

**这里有三个方法**：

*  查询所有用户`getUser`
 *  增加指定用户`addUser`
 *  删除指定id的用户`deleteUser`

public interface UserMapper { 
        public List<User> getUser();
    
        //添加一个用户
        public int addUser(User user);
    
        //删除一个用户
        public int deleteUser(int id);
    
    }

## 4. 编写UserMapper.xml配置文件 ##

这里故意将`deleteUser`的 `sql语句` 写错 ，`delete` 写成 `deletes`

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    <mapper namespace="mapper.UserMapper">
        <select id="getUser" resultType="pojo.User">
            select * from mybatis.user
        </select>
    
        <insert id="addUser" parameterType="pojo.User">
            insert into mybatis.user (id,name,pwd) values (#{id},#{name},#{pwd})
        </insert>
    
        <delete id="deleteUser" parameterType="int">
            deletes from mybatis.user where id=#{id}
        </delete>
    </mapper>

## 5. 编写Spring配置文件applicationContext.xml ##

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation="http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/tx https://www.springframework.org/schema/tx/spring-tx.xsd http://www.springframework.org/schema/aop https://www.springframework.org/schema/aop/spring-aop.xsd">
        
    	
        <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
            <property name="driverClassName" value="com.mysql.cj.jdbc.Driver"/>
            <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSH=true&useUnicode=true&characterEncoding=UTF-8"/>
            <property name="username" value="root"/>
            <property name="password" value="200024"/>
        </bean>
        
    	
        <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
            <property name="dataSource" ref="dataSource"/>
            <property name="mapperLocations" value="classpath:mapper/UserMapper.xml"/>
        </bean>
    
        
        <bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">
            <constructor-arg index="0" ref="sqlSessionFactory"/>
        </bean>
    
    </beans>

## 6. 编写UserMapper接口实现类 ##

在`getUser`方法中：

*  先后调用 `addUser` 和 `deleteUser` 两个方法，增加和删除同一个用户

public class UserMapperImpl implements UserMapper { 
        private SqlSessionTemplate sqlSession;
    
        public void setSqlSession(SqlSessionTemplate sqlSession) { 
            this.sqlSession = sqlSession;
        }
    
        public List<User> getUser() { 
            User user = new User(5, "小王", "1212");
            UserMapper mapper = sqlSession.getMapper(UserMapper.class);
            mapper.addUser(user);
            mapper.deleteUser(5);
            return mapper.getUser();
        }
    
        public int addUser(User user) { 
            return sqlSession.getMapper(UserMapper.class).addUser(user);
        }
    
        public int deleteUser(int id) { 
            return sqlSession.getMapper(UserMapper.class).deleteUser(id);
        }
    }

然后在Spring配置文件`applicationContext`中创建该实现类对象，并注入私有属性sqlSession的值

## 7. 编写测试类 ##

public class Test { 
        @org.junit.Test
        public void test() { 
            ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
            UserMapper userMapper = (UserMapper) context.getBean("userMapper");
            List<User> users = userMapper.getUser();
            for (User user : users) { 
                System.out.println(user);
            }
        }
    }

## 8. 运行查看结果 ##

![image-20200815114751477][]  
**不出所料，报错了，因为我们的`sql`语句写错了**  
![image-20200815114816850][]  
**我们刷新数据表看看**  
![image-20200815114842612][]  
发现还是增加了`5号`用户，这就是因为没有添加`事务`，不会`要么都成功，要么都失败`

## 9. 修改，增加声明式事务支持 ##

> 以下操作均添加在Spring配置文件`applicationContext.xml`中

要引入`tx`，`aop`约束  
![image-20200815124643851][]

### 1. 开启Spring的事务处理功能 ###

*  创建一个 `DataSourceTransactionManager` 对象，传入上述创建好的`dataSource`对象

<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource"/>
    </bean>

### 2. 配置事务通知 ###

这里使用**事务`tx`命名空间配置**

*  常用的**两个属性**
    
     *  用`name`属性规定配置事务的**方法**
     *  用`propagation`属性配置事务的**传播特性**，默认为`REQUIRED`
        
        <table> 
         <thead> 
          <tr> 
           <th>REQUIRED</th> 
           <th>支持当前事务，如果当前没有事务，就新建一个事务</th> 
          </tr> 
         </thead> 
         <tbody> 
          <tr> 
           <td>REQUIRED_NEW</td> 
           <td>新建事务，如果当前存在事务，把当前事务挂起</td> 
          </tr> 
          <tr> 
           <td>SUPPORTS</td> 
           <td>支持当前事务，如果当前没有事务，就以非事务方式执行</td> 
          </tr> 
          <tr> 
           <td>NOT_SUPPORTED</td> 
           <td>以非事务方式执行操作，如果当前存在事务，就把当前事务挂起</td> 
          </tr> 
          <tr> 
           <td>MANDATORY</td> 
           <td>支持当前事务，如果当前没有事务，就抛出异常</td> 
          </tr> 
          <tr> 
           <td>NEVER</td> 
           <td>以非事务方式执行，如果当前存在事务，则抛出异常</td> 
          </tr> 
          <tr> 
           <td>NESTED</td> 
           <td>支持当前事务，如果当前事务存在，则执行一个嵌套事务，如果当前没有事务，就新建一个事务</td> 
          </tr> 
         </tbody> 
        </table>

<tx:advice id="txAdvice" transaction-manager="transactionManager">
        
        
        <tx:attributes>
            <tx:method name="add" propagation="REQUIRED"/>
            <tx:method name="delete" propagation="REQUIRED"/>
            <tx:method name="update" propagation="REQUIRED"/>
            <tx:method name="query" read-only="true"/>
            <tx:method name="*" propagation="REQUIRED"/>
        </tx:attributes>
    </tx:advice>

### 3. 结合AOP实现事务织入 ###

<aop:config>
        <aop:pointcut id="txPointCut" expression="execution(* mapper.*.*(..))"/>
        <aop:advisor advice-ref="txAdvice" pointcut-ref="txPointCut"/>
    </aop:config>

## 10. 再次测试 ##

数据表中删除上述插入的5号数据，再次运行测试，同样的报错信息  
![image-20200815124835414][]  
但是，我们重新刷新表格，发现5号用户没有添加进来，这就是因为`事务`，`要么都成功，要么都失败`  
![image-20200815124909182][]

[image-20200815112250177]: https://gitee.com/zhong_siru/images/raw/master//img/image-20200815112250177.png
[image-20200815112204178]: https://gitee.com/zhong_siru/images/raw/master//img/image-20200815112204178.png
[image-20200815114751477]: /images/20221124/5d156f932fdb40a987b6d548b10f1ee2.png
[image-20200815114816850]: /images/20221124/ff7784965b754e7fa42df012809dc1e7.png
[image-20200815114842612]: https://gitee.com/zhong_siru/images/raw/master//img/image-20200815114842612.png
[image-20200815124643851]: /images/20221124/38254c6ab50e4953b7958fac5e49ef63.png
[image-20200815124835414]: /images/20221124/0b03360b75f84e65af71ddee1e7a2273.png
[image-20200815124909182]: https://gitee.com/zhong_siru/images/raw/master//img/image-20200815124909182.png