事務是一系列的動做,它們綜合在一塊兒纔是一個完整的工做單元,這些動做必須所有完成,若是有一個失敗的話,那麼事務就會回滾到最開始的狀態,彷彿什麼都沒發生過同樣。java
在企業級應用程序開發中,事務管理必不可少的技術,用來確保數據的完整性和一致性。 mysql
事務有四個特性:ACIDweb
原子性(Atomicity):事務是一個原子操做,由一系列動做組成。事務的原子性確保動做要麼所有完成,要麼徹底不起做用。spring
一致性(Consistency):一旦事務完成(無論成功仍是失敗),系統必須確保它所建模的業務處於一致的狀態,而不會是部分完成部分失敗。在現實中的數據不該該被破壞。sql
隔離性(Isolation):可能有許多事務會同時處理相同的數據,所以每一個事務都應該與其餘事務隔離開來,防止數據損壞。數據庫
持久性(Durability):一旦事務完成,不管發生什麼系統錯誤,它的結果都不該該受到影響,這樣就能從任何系統崩潰中恢復過來。一般狀況下,事務的結果被寫到持久化存儲器中。express
舉個簡單的例子:例如陳多多給陳多糖轉錢,可是在轉錢的過程當中出現了問題,銀行系統出現了問題,那麼陳多多的錢給陳多糖轉過去了,可是陳多糖卻沒有收到錢?這個就很尷尬apache
那麼怎麼避免?出現這個問題啦?這個時候就要用到咱們spring中的事務管理json
第一步、導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接口和實體類
package com.bdqn.zmj.dao; import com.bdqn.zmj.entity.user; import java.util.List; public interface UserMapper { List<user> GetList(); //轉出 void jian(); //轉入 void add(); }
package com.bdqn.zmj.entity; public class user { int uid; String uname; int money; //注意這裏對應的是映射文件裏的UserId,而不是這類裏的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層代碼
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; /* * 事務通常都加在service層,由於service調用dao * 當servoce調用多個dao方法的時候事務以下處理 * 加載controller層:當controller調用多個service方法發的時候事務如何處理 * * */ @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、數據庫配置文件
<?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"/> <!--兩個框架整合:幾乎全部的配置都交給了spring,由於spring專門作整合--> <!--1.數據源--> <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}"/> <!--其餘數據庫鏈接池配置省略,好比:鏈接個數,最大鏈接數。。。。--> </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> <!--配置接口掃描--> <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer"> <property name="basePackage" value="com.bdqn.zmj.dao"/> <property name="sqlSessionFactoryBeanName" value="sessionFactoryBean"/> </bean> <!--配置事務管理器--> <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager"> <property name="dataSource" ref="dataSource"/> </bean> 配置事務傳播行爲,就是 有事務的方法調用 沒有事務的方法的時候,事務應該如何傳遞 <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"> <!--經過這個配置文件,完成mybatis與數據庫的鏈接 --> <configuration> <settings> <setting name="logImpl" value="LOG4J"/> </settings> <!-- 設置類的別名 --> <typeAliases> <!-- <typeAlias alias="User" type="com.wu.pojo.User"/> --> <!-- 根據包取別名,把包下面的全部類都按類名來取別名 --> <!-- 這用能夠簡化代碼量 --> <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、編寫測試類
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 //事務,下面的方法只有全執行和全不執行兩種狀態 public void test2(){ UserService service = context.getBean("userService", UserService.class); service.transfer(); } }
數據庫中的數據沒有變化,操做失敗,數據回滾回去了!!!
只須要改變兩個地方便可
第1、service層,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; /* * 事務通常都加在service層,由於service調用dao * 當servoce調用多個dao方法的時候事務以下處理 * 加載controller層:當controller調用多個service方法發的時候事務如何處理 * * */ @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,只留下配置事務管理器、而後加上掃描事務的<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"/> <!--兩個框架整合:幾乎全部的配置都交給了spring,由於spring專門作整合--> <!--1.數據源--> <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}"/> <!--其餘數據庫鏈接池配置省略,好比:鏈接個數,最大鏈接數。。。。--> </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> <!--配置接口掃描--> <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer"> <property name="basePackage" value="com.bdqn.zmj.dao"/> <property name="sqlSessionFactoryBeanName" value="sessionFactoryBean"/> </bean> <!--配置事務管理器--> <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager"> <property name="dataSource" ref="dataSource"/> </bean> <!--配置事務傳播行爲,就是 有事務的方法調用 沒有事務的方法的時候,事務應該如何傳遞--> <!--<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>
這兩種方式均可以實現事務配置、可是咱們不配置細節的話,用的都是註解的方式、xml方式用於比較細緻的配置,好比什麼銀行轉帳什麼的