Spring系列 12
12、声明式事务
12.1、回顾事务
- 把一组业务当成一个业务来做:要么都成功,要么都失败
- 事务在项目开发中,十分的重要,涉及到数据的一致性问题
- 确保完整性和一致性
务的ACID原则:
- 原子性(Atomicity):
- 一致性(Consisitency)
- 隔离性(Isolation)
- 多个业务可能操作同一个资源,防止数据损坏
- 持久性(Durability)
- 事务一旦提交,无论系统发生什么问题,结果都不会再被影响,被持久化的写到存储器中。
12.2、Spring中的事务管理
- 声明式事务:AOP
- 编程式事务:需要在代码中,进行事务的管理
思考:
为什么需要事务?
- 如果不配置事务,可能存在事务提交不一致的情况;
- 如果不在Spring中取配置声明式事务,我们就需要在代码中手动配置事务;
- 事务在项目开发中,十分的重要,涉及到数据的一致性问题,不容马虎。
下面用一个实例来展示Sprubg中的事务管理
- 编写实体类
## User.java
@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
private int id;
private String name;
private String pwd;
}
## UserMapper接口
public interface UserMapper {
public List<User> selectUser();
public int addUser(User user);
public int deleteUser(int id);
}
## UserMapper.xml
<mapper namespace="com.only.mapper.UserMapper">
<select id="selectUser" resultType="user">
select * from mybatis.user;
</select>
<insert id="addUser" parameterType="user">
insert into mybatis.user (id,name,pwd) values (#{id},#{name},#{pwd});
</insert>
<delete id="deleteUser" parameterType="int">
delete from mybatis.user where id = #{id}
</delete>
</mapper>
## UserMapperImpl.java
public class UserMapperImpl extends SqlSessionDaoSupport implements UserMapper {
public List<User> selectUser() {
User user = new User(5, "小吴", "111222333");
UserMapper mapper = getSqlSession().getMapper(UserMapper.class);
mapper.addUser(user);
mapper.deleteUser(4);
return mapper.selectUser();
}
public int addUser(User user) {
return getSqlSession().getMapper(UserMapper.class).addUser(user);
}
public int deleteUser(int id) {
return getSqlSession().getMapper(UserMapper.class).deleteUser(id);
}
}
- 编写配置文件
## spring-dao.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:aop="http://www.springframework.org/schema/aop"
xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx.xsd">
<!-- DataSource:使用Spring的数据源替换Mybatis的配置
我们这里使用Spring提供的JDBC
-->
<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/mybatis?useSSL=true&useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC"/>
<property name="username" value="root"/>
<property name="password" value="123456"/>
</bean>
<!-- sqlSessionFactory -->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource"/>
<!-- 绑定Mybatis配置文件 -->
<property name="configLocation" value="classpath:mybatis_config.xml"/>
<property name="mapperLocations" value="classpath:com/only/mapper/*.xml"/>
</bean>
<!-- sqlSessionTemplate: 就是我们使用的SqlSession -->
<bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">
<!-- 只能使用构造器注入sqlSessionFactory,因为它没有set方法 -->
<constructor-arg index="0" ref="sqlSessionFactory"/>
</bean>
<!-- 配置声明式事务 -->
<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<constructor-arg name="dataSource" ref="dataSource"/>
</bean>
<!-- 结合AOP实现事务的织入 -->
<!-- 配置事务通知: -->
<tx:advice id="txAdvice" transaction-manager="transactionManager">
<!-- 给哪些方法配置事务 -->
<!-- 配置事务的传播特性: new propagation -->
<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>
<!--配置事务切入-->
<aop:config>
<aop:pointcut id="txPointCut" expression="execution(* com.only.mapper.*.*(..))"/>
<aop:advisor advice-ref="txAdvice" pointcut-ref="txPointCut"/>
</aop:config>
</beans>
## 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"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd">
<import resource="spring-dao.xml"/>
<bean id="userMapper" class="com.only.mapper.UserMapperImpl">
<property name="sqlSessionFactory" ref="sqlSessionFactory"/>
</bean>
</beans>
## mybatis-config.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<typeAliases>
<package name="com.only.pojo"/>
</typeAliases>
</configuration>
- 测试
public class MyTest {
@Test
public void test() throws IOException {
ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
UserMapper mapper = context.getBean("userMapper", UserMapper.class);
List<User> userList = mapper.selectUser();
for (User user : userList) {
System.out.println(user);
}
}
}