事务
事务四个属性ACID
1. 原子性(atomicity)
- 事务是原子性操作,由一系列动作组成,事务的原子性确保动作要么全部完成,要么完全不起
作用
2. 一致性(consistency)
- 一旦所有事务动作完成,事务就要被提交。数据和资源处于一种满足业务规则的一致性状态中
3. 隔离性(isolation)
- 可能多个事务会同时处理相同的数据,因此每个事务都应该与其他事务隔离开来,防止数据损
坏
4. 持久性(durability)
- 事务一旦完成,无论系统发生什么错误,结果都不会受到影响。通常情况下,事务的结果被写
到持久化存储器中
Spring中的事务管理
Spring在不同的事务管理API之上定义了一个抽象层,使得开发人员不必了解底层的事务管理API就可以使用Spring的事务管理机制。Spring支持编程式事务管理和声明式的事务管理。
编程式事务管理
- 将事务管理代码嵌到业务方法中来控制事务的提交和回滚
- 缺点:必须在每个事务操作业务逻辑中包含额外的事务管理代码
声明式事务管理
- 一般情况下比编程式事务好用。
- 将事务管理代码从业务方法中分离出来,以声明的方式来实现事务管理。
- 将事务管理作为横切关注点,通过aop方法模块化。Spring中通过Spring AOP框架支持声明式事务
- 管理。
环境搭建
导入相关依赖
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.47</version>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.5.2</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>5.3.6</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>5.3.6</version>
</dependency>
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
<version>1.9.4</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.mybatis/mybatis-spring -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis-spring</artifactId>
<version>2.0.6</version>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>1.18.8</version>
</dependency>
</dependencies>
<build>
<resources>
<resource>
<directory>src/main/resources</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<filtering>true</filtering>
</resource>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<filtering>true</filtering>
</resource>
</resources>
</build>
编写实体类(需要导入lombok依赖)
package com.kuang.pojo;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
private int id;
private String name;
private String pwd;
}
编写实现接口
package com.kuang.mapper;
import com.kuang.pojo.User;
import java.util.List;
public interface UserMapper {
public List<User> selectUser();
//添加一个用户
int addUser(User user);
//根据id删除用户
int deleteUser(int id);
}
编写配置文件
UserMapper.xml
注意:delete故意写错
<?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="com.study.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">
deletes from mybatis.user where id=#{id}
</delete>
</mapper>
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">
<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=false&useUnicode=true&characterEncoding=UTF-8"/>
<property name="username" value="root"/>
<property name="password" value="123456"/>
</bean>
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource"/>
<property name="configLocation" value="classpath:mybatis-config.xml"/>
<property name="mapperLocations" value="classpath:com/kuang/mapper/*.xml"/>
</bean>
<bean id="sqlSession" class="org.mybatis.spring.SqlSessionTemplate">
<constructor-arg index="0" 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.kuang.pojo"/>
</typeAliases>
</configuration>
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.kuang.mapper.UserMapperImpl">
<property name="sqlSessionFactory" ref="sqlSessionFactory"/>
</bean>
</beans>
编写接口实现类
package com.kuang.mapper;
import com.kuang.pojo.User;
import org.mybatis.spring.SqlSessionTemplate;
import org.mybatis.spring.support.SqlSessionDaoSupport;
import java.util.List;
public class UserMapperImpl extends SqlSessionDaoSupport implements UserMapper{
@Override
public List<User> selectUser() {
User user =new User(30,"bbb","123456");
UserMapper mapper = getSqlSession().getMapper(UserMapper.class);
mapper.addUser(user);
mapper.deleteUser(30);
return mapper.selectUser();
}
@Override
public int addUser(User user) {
return getSqlSession().getMapper(UserMapper.class).addUser(user);
}
@Override
public int deleteUser(int id) {
return getSqlSession().getMapper(UserMapper.class).deleteUser(id);
}
}
编写测试类
import com.kuang.mapper.UserMapper;
import com.kuang.pojo.User;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import java.util.List;
public class MyText {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
UserMapper userMapper = context.getBean("userMapper", UserMapper.class);
List<User> userList = userMapper.selectUser();
for (User user : userList) {
System.out.println(user);
}
}
}
测试
运行测试前数据库
运行测试出错
刷新数据库数据添加成功
在程序开发中,这样的BUG重的,所以我们需要在spring中开启事务防止这样的漏洞发生
在spring中使用事务
一、在spring配置文件开启JDBC事务
<!--声明式事务-->
<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<property name="dataSource" ref="dataSource" />
</bean>
二、配置好事务管理器后我们需要去配置事务的通知
<!--结合AOP实现事务的织入-->
<!--配置事务的类-->
<tx:advice id="txAdvice" transaction-manager="transactionManager">
<tx:attributes>
<!--给哪些方法配置事务-->
<!--配置事务的传播特性 propagation:默认REQUIRED-->
<tx:method name="add" propagation="REQUIRED"/>
<tx:method name="delete" propagation="REQUIRED"/>
<tx:method name="update" propagation="REQUIRED"/>
<!--read-only:只读-->
<tx:method name="select" read-only="true"/>
<tx:method name="*" propagation="REQUIRED"/>
</tx:attributes>
</tx:advice>
三、设置事务的切入
<!--配置事务的切入-->
<aop:config>
<aop:pointcut id="txPointCut" expression="execution(* com.kuang.mapper.*.*(..))"/>
<aop:advisor advice-ref="txAdvice" pointcut-ref="txPointCut"/>
</aop:config>
四、删除刚才添加的数据库数据
五、运行测试
运行报错
数据库没有添加数据