事务是一系列的动做,它们综合在一块儿才是一个完整的工做单元,这些动做必须所有完成,若是有一个失败的话,那么事务就会回滚到最开始的状态,仿佛什么都没发生过同样。java
在企业级应用程序开发中,事务管理必不可少的技术,用来确保数据的完整性和一致性。 mysql
事务有四个特性:ACIDweb
原子性(Atomicity):事务是一个原子操做,由一系列动做组成。事务的原子性确保动做要么所有完成,要么彻底不起做用。spring
一致性(Consistency):一旦事务完成(无论成功仍是失败),系统必须确保它所建模的业务处于一致的状态,而不会是部分完成部分失败。在现实中的数据不该该被破坏。sql
隔离性(Isolation):可能有许多事务会同时处理相同的数据,所以每一个事务都应该与其余事务隔离开来,防止数据损坏。数据库
持久性(Durability):一旦事务完成,不管发生什么系统错误,它的结果都不该该受到影响,这样就能从任何系统崩溃中恢复过来。一般状况下,事务的结果被写到持久化存储器中。express
举个简单的例子:例如陈多多给陈多糖转钱,可是在转钱的过程当中出现了问题,银行系统出现了问题,那么陈多多的钱给陈多糖转过去了,可是陈多糖却没有收到钱?这个就很尴尬apache
那么怎么避免?出现这个问题啦?这个时候就要用到咱们spring中的事务管理json
第一步、导jar包api
<dependencies> <dependency> <groupId>log4j</groupId> <artifactId>log4j</artifactId> <version>1.2.17</version> </dependency> <!-- spring start --> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>LATEST</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context-support</artifactId> <version>LATEST</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-instrument</artifactId> <version>LATEST</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-orm</artifactId> <version>LATEST</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-oxm</artifactId> <version>LATEST</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-messaging</artifactId> <version>LATEST</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-web</artifactId> <version>LATEST</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>LATEST</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>LATEST</version> </dependency> <!-- spring end --> <dependency> <groupId>com.alibaba</groupId> <artifactId>fastjson</artifactId> <version>1.2.47</version> </dependency> <dependency> <groupId>com.mchange</groupId> <artifactId>c3p0</artifactId> <version>0.9.5.2</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>8.0.15</version> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>jstl</artifactId> <version>1.2</version> </dependency> <dependency> <groupId>taglibs</groupId> <artifactId>standard</artifactId> <version>1.1.2</version> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>javax.servlet-api</artifactId> <version>4.0.0</version> <scope>provided</scope> </dependency> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis-spring</artifactId> <version>1.3.2</version> </dependency> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.5.0</version> </dependency> <!-- https://mvnrepository.com/artifact/aspectj/aspectjrt --> <dependency> <groupId>aspectj</groupId> <artifactId>aspectjrt</artifactId> <version>1.5.4</version> </dependency> <!-- https://mvnrepository.com/artifact/aspectj/aspectjweaver --> <dependency> <groupId>aspectj</groupId> <artifactId>aspectjweaver</artifactId> <version>1.5.4</version> </dependency> </dependencies> <build> <resources> <resource> <directory>src/main/java</directory> <includes> <include>**/*.xml</include> </includes> <filtering>false</filtering> </resource> </resources> </build>
第二步、建立Mapper接口和实体类
package com.bdqn.zmj.dao; import com.bdqn.zmj.entity.user; import java.util.List; public interface UserMapper { List<user> GetList(); //转出 void jian(); //转入 void add(); }
package com.bdqn.zmj.entity; public class user { int uid; String uname; int money; //注意这里对应的是映射文件里的UserId,而不是这类里的uid public int getUserId() { return uid; } public void setUserId(int uid) { this.uid = uid; } public String getUserName() { return uname; } public void setUserName(String uname) { this.uname = uname; } public int getMoney() { return money; } public void setMoney(int money) { this.money = money; } }
第三步、建立mybatis映射文件
<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <mapper namespace="com.bdqn.zmj.dao.UserMapper"> <resultMap id="userMap" type="user"> <id property="userId" column="uid" /> <result property="userName" column="uname"/> <result property="money" column="money" /> </resultMap> <select id="GetList" resultMap="userMap"> select * from t_user </select> <update id="jian"> update t_user set money = money-500 where uid =1 </update> <update id="add"> update t_user set money = money +500 where uid =2 </update> </mapper>
第四步、Service层代码
package com.bdqn.zmj.service; import com.bdqn.zmj.dao.UserMapper; import com.bdqn.zmj.entity.user; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import org.springframework.transaction.annotation.Transactional; import java.util.List; /* * 事务通常都加在service层,由于service调用dao * 当servoce调用多个dao方法的时候事务以下处理 * 加载controller层:当controller调用多个service方法发的时候事务如何处理 * * */ @Service public class UserService{ @Autowired UserMapper dao; public List<user> GetList(){ return dao.GetList(); } @Transactional public void transfer() { dao.jian(); int i = 10/0; dao.add(); } }
第五步、ApplicationContext配置文件、mybatis映射文件、Log4J配置文件、数据库配置文件
<?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" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd"> <context:component-scan base-package="com.bdqn.zmj"/> <!--注入配置文件--> <context:property-placeholder location="classpath:db.properties"/> <!--两个框架整合:几乎全部的配置都交给了spring,由于spring专门作整合--> <!--1.数据源--> <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"> <property name="driverClass" value="${driver}"/> <property name="jdbcUrl" value="${url}"/> <property name="user" value="${user}"/> <property name="password" value="${password}"/> <!--其余数据库链接池配置省略,好比:链接个数,最大链接数。。。。--> </bean> <!--配置sqlSessionFactiorBean--> <bean id="sessionFactoryBean" class="org.mybatis.spring.SqlSessionFactoryBean"> <property name="configLocation" value="classpath:mybatis-config.xml"></property> <property name="mapperLocations" value="com/bdqn/zmj/mapper/*.xml"></property> <property name="dataSource" ref="dataSource"></property> </bean> <!--配置接口扫描--> <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer"> <property name="basePackage" value="com.bdqn.zmj.dao"/> <property name="sqlSessionFactoryBeanName" value="sessionFactoryBean"/> </bean> <!--配置事务管理器--> <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager"> <property name="dataSource" ref="dataSource"/> </bean> 配置事务传播行为,就是 有事务的方法调用 没有事务的方法的时候,事务应该如何传递 <tx:advice id="txadvice" transaction-manager="transactionManager"> <tx:attributes> <tx:method name="transfer" propagation="REQUIRED"/> </tx:attributes> </tx:advice> <!--配置切面--> <aop:config> <aop:pointcut id="pointcut" expression="execution(* com.bdqn.zmj..*.*(..))"/> <aop:advisor advice-ref="txadvice" pointcut-ref="pointcut"/> </aop:config> </beans>
<?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"> <!--经过这个配置文件,完成mybatis与数据库的链接 --> <configuration> <settings> <setting name="logImpl" value="LOG4J"/> </settings> <!-- 设置类的别名 --> <typeAliases> <!-- <typeAlias alias="User" type="com.wu.pojo.User"/> --> <!-- 根据包取别名,把包下面的全部类都按类名来取别名 --> <!-- 这用能够简化代码量 --> <package name="com.bdqn.zmj.entity"/> </typeAliases> </configuration>
log4j.rootLogger=info,CONSOLE ############################################################# # Console Appender ############################################################# log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender log4j.appender.Threshold=info ##log4j.appender.CONSOLE.DatePattern=yyyy-MM-dd log4j.appender.CONSOLE.Target=System.out log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout log4j.appender.CONSOLE.layout.ConversionPattern= %d{yyyy-M-d HH:mm:ss}%x[%5p] %m%n
driver=com.mysql.cj.jdbc.Driver url=jdbc:mysql://localhost:3306/fresh?serverTimezone=UTC user=root password=root
第六步、编写测试类
package com.bdqn.zmj.test; import com.bdqn.zmj.entity.user; import com.bdqn.zmj.service.UserService; import org.junit.Before; import org.junit.Test; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import org.springframework.transaction.annotation.Transactional; import java.util.List; public class Testone { ApplicationContext context = null; @Before public void load(){ context = new ClassPathXmlApplicationContext("applicationContext.xml"); } @Test //事务,下面的方法只有全执行和全不执行两种状态 public void test2(){ UserService service = context.getBean("userService", UserService.class); service.transfer(); } }
数据库中的数据没有变化,操做失败,数据回滚回去了!!!
只须要改变两个地方便可
第1、service层,方法上加上 @Transactional
package com.bdqn.zmj.service; import com.bdqn.zmj.dao.UserMapper; import com.bdqn.zmj.entity.user; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Service; import org.springframework.transaction.annotation.Transactional; import java.util.List; /* * 事务通常都加在service层,由于service调用dao * 当servoce调用多个dao方法的时候事务以下处理 * 加载controller层:当controller调用多个service方法发的时候事务如何处理 * * */ @Service public class UserService{ @Autowired UserMapper dao; public List<user> GetList(){ return dao.GetList(); } @Transactional public void transfer() { dao.jian(); int i = 10/0; dao.add(); } }
第二步、ApplicationContext.xml中,只留下配置事务管理器、而后加上扫描事务的<tx:annotation-driven />
<?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" xmlns:context="http://www.springframework.org/schema/context" xmlns:mvc="http://www.springframework.org/schema/mvc" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd"> <context:component-scan base-package="com.bdqn.zmj"/> <!--注入配置文件--> <context:property-placeholder location="classpath:db.properties"/> <!--两个框架整合:几乎全部的配置都交给了spring,由于spring专门作整合--> <!--1.数据源--> <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"> <property name="driverClass" value="${driver}"/> <property name="jdbcUrl" value="${url}"/> <property name="user" value="${user}"/> <property name="password" value="${password}"/> <!--其余数据库链接池配置省略,好比:链接个数,最大链接数。。。。--> </bean> <!--配置sqlSessionFactiorBean--> <bean id="sessionFactoryBean" class="org.mybatis.spring.SqlSessionFactoryBean"> <property name="configLocation" value="classpath:mybatis-config.xml"></property> <property name="mapperLocations" value="com/bdqn/zmj/mapper/*.xml"></property> <property name="dataSource" ref="dataSource"></property> </bean> <!--配置接口扫描--> <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer"> <property name="basePackage" value="com.bdqn.zmj.dao"/> <property name="sqlSessionFactoryBeanName" value="sessionFactoryBean"/> </bean> <!--配置事务管理器--> <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager"> <property name="dataSource" ref="dataSource"/> </bean> <!--配置事务传播行为,就是 有事务的方法调用 没有事务的方法的时候,事务应该如何传递--> <!--<tx:advice id="txadvice" transaction-manager="transactionManager">--> <!--<tx:attributes>--> <!--<tx:method name="transfer" propagation="REQUIRED"/>--> <!--</tx:attributes>--> <!--</tx:advice>--> <!--<!–配置切面–>--> <!--<aop:config>--> <!--<aop:pointcut id="pointcut" expression="execution(* com.bdqn.zmj..*.*(..))"/>--> <!--<aop:advisor advice-ref="txadvice" pointcut-ref="pointcut"/>--> <!--</aop:config>--> <tx:annotation-driven /> </beans>
这两种方式均可以实现事务配置、可是咱们不配置细节的话,用的都是注解的方式、xml方式用于比较细致的配置,好比什么银行转帐什么的