spring tranaction 事务入门

2022-09-02 18:45:24

一、事务四个属性

原子性（atomicity）。一个事务是一个不可分割的工作单位，事务中包括的诸操作要么都做，要么都不做。

一致性（consistency）。事务必须是使数据库从一个一致性状态变到另一个一致性状态。一致性与原子性是密切相关的。

隔离性（isolation）。一个事务的执行不能被其他事务干扰。即一个事务内部的操作及使用的数据对并发的其他事务是隔离的，并发执行的各个事务之间不能互相干扰。

持久性（durability）。持久性也称永久性（permanence），指一个事务一旦提交，它对数据库中数据的改变就应该是永久性的。接下来的其他操作或故障不应该对其有任何影响。

二、事务的重要性

打个最简单的比方吧，A和B两人之间的支付宝转账问题，A向B转账50RMB，正常的结果是，A - 50 并且 B + 50；但如果是下面这种情况，那就杯具了，A - 50 成功，而B + 50 失败。这样一来岂不是 A亏大了！谁还敢随意转账？就算是首富，也不敢随意转账O(∩_∩)O哈！

所以，在进行 A - 50 和 B + 50 需要添加事务管理。

三、先看下没有加事务的Demo, 看完就知道事务的重要性啦~

(1)、整体结构、

（2）、jar 包

（3）、SQL语句

创建数据库

create database spring;

建立表

create table countmoney(idCard int primary key auto_increment,name varchar(),money int);

插入两条记录

insert into countmoney(name,money)values('xx',);

insert into countmoney(name,money)values('++',);

 结果

 select * from countmoney;

+--------+------+-------+
| idCard | name | money |
+--------+------+-------+
| 1 | xx | 300 |
| 2 | ++ | 300 |
+--------+------+-------+

（4）、代码

model 层

 package com.xpw.model;

 public class Count {

     private int idCard;

     private String name;

     private int money;

     public Count(){

     }

     public int getIdCard() {

         return idCard;

     }

     public void setIdCard(int idCard) {

         this.idCard = idCard;

     }

     public String getName() {

         return name;

     }

     public void setName(String name) {

         this.name = name;

     }

     public int getMoney() {

         return money;

     }

     public void setMoney(int money) {

         this.money = money;

     }

 }

dao 层

 package com.xpw.dao;

 public interface TradeDao {

     public void outputMoney(int idCard, int money);

     public void inputMoney(int idCard, int money);

 }

dao impl 层

 package com.xpw.dao.impl;

 import org.springframework.jdbc.core.JdbcTemplate;

 import org.springframework.jdbc.core.namedparam.MapSqlParameterSource;

 import org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate;

 import org.springframework.jdbc.core.namedparam.SqlParameterSource;

 import com.xpw.dao.TradeDao;

 public class TradeDaoImpl implements TradeDao {

     private NamedParameterJdbcTemplate namedParameterJdbcTemplate;

     public void setNamedParameterJdbcTemplate(

             NamedParameterJdbcTemplate namedParameterJdbcTemplate) {

         this.namedParameterJdbcTemplate = namedParameterJdbcTemplate;

     }

     @Override

     public void outputMoney(int idCard, int count) {

         String sql = "update trademoney set money = money -:count where idCard = :idCard";

         MapSqlParameterSource param = new MapSqlParameterSource();

         param.addValue("count", count);

         param.addValue("idCard", idCard);

         this.namedParameterJdbcTemplate.update(sql, param);

     }

     @Override

     public void inputMoney(int idCard, int count) {

         //我们故意在此出错，抛出异常，让 B + 50失败

         System.out.println(1/0);

         String sql = "update trademoney set money = money + :count where idCard = :idCard";

         MapSqlParameterSource param = new MapSqlParameterSource();

         param.addValue("count", count);

         param.addValue("idCard", idCard);

         this.namedParameterJdbcTemplate.update(sql, param);

     }

 }

Service层

 package com.xpw.service;

 public interface TradeService {

     public void trade(int fromIdCard, int toIdCard, int money);

 }

Service impl 层

 package com.xpw.service.impl;

 import com.xpw.dao.TradeDao;

 import com.xpw.service.TradeService;

 public class TradeServiceImpl implements TradeService {

     private TradeDao tradeDao;

     public void setTradeDao(TradeDao tradeDao) {

         this.tradeDao = tradeDao;

     }

     @Override

     public void trade(int fromIdCard, int toIdCard, int money) {

         this.tradeDao.outputMoney(fromIdCard, money);

         this.tradeDao.inputMoney(toIdCard, money);

     }

 }

（5）文件配置信息

beans.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:context="http://www.springframework.org/schema/context"

     xsi:schemaLocation="http://www.springframework.org/schema/beans

         http://www.springframework.org/schema/beans/spring-beans.xsd

         http://www.springframework.org/schema/context

         http://www.springframework.org/schema/context/spring-context.xsd">    

     <context:component-scan base-package="org.springframework.docs.test" />

     <context:property-placeholder location="jdbc.properties"/>    

     <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">

         <property name="driverClassName" value="${jdbc.driverClassName}"/>

         <property name="url" value="${jdbc.url}"/>

         <property name="username" value="${jdbc.username}"/>

         <property name="password" value="${jdbc.password}"/>

     </bean>

     <bean id="namedParameterJdbcTemplate" class="org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate">

         <constructor-arg ref="dataSource"></constructor-arg>

     </bean>

     <bean id="tradeDao" class="com.xpw.dao.impl.TradeDaoImpl">

         <property name="namedParameterJdbcTemplate" ref="namedParameterJdbcTemplate"/>

     </bean>

     <bean id="tradeService" class="com.xpw.service.impl.TradeServiceImpl">

         <property name="tradeDao" ref="tradeDao"></property>

     </bean>

 </beans>

jdbc.properties

jdbc.driverClassName=com.mysql.jdbc.Driver

jdbc.url=jdbc:mysql://localhost:3306/spring

jdbc.username=root

jdbc.password=root

(6)测试

package com.xpw.trade;

import org.junit.Before;

import org.junit.Test;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.xpw.service.TradeService;

public class TradeTest {

    private static ApplicationContext ac;

    @Before

    public void init(){

        ac = new ClassPathXmlApplicationContext("beans.xml");

    }

    @Test

    public void testTrade(){

        TradeService ts = (TradeService) ac.getBean("tradeService");

        int fromIdCard = 1;

        int toIdCard = 2;

        int money = 50;

        ts.trade(fromIdCard, toIdCard, money);

    }

}

结果

select * from trademoney;

+--------+------+-------+

| idCard | name | money |

+--------+------+-------+

|      1 | xx   |   250 |

|      2 | ++   |   300 |

+--------+------+-------+

2 rows in set (0.00 sec)

由于，在 inputmoney()方法，我们故意 做1/0操作，也没有做try catch ，导致不会往下执行向B账户添加50的业务，所以 A亏了50。。。

从上面的结果我们知道了事务的重要性了吧。。A - 50 和 B + 50 必须同时成功，才可以称为一个成功的交易，一旦 谁出错，就必须回滚！即 不能 将 A - 50 ， B 也不能 被 + 50

下面，我们就添加事务管理吧。。当然，事务管理有两种，详情见如下

四、spring 事务分类

1、编程式事务管理

Spring 提供的事务模版类：org.springframework.transaction.support.TransactionTemplate
事务管理器：org.springframework.jdbc.datasource.DataSourceTransactionManager

service impl 层的代码有所改动（注意，便于阅者copy实践，我就把整个类的代码贴出来，下同）

 package com.xpw.service.impl;

 import org.springframework.transaction.TransactionStatus;

 import org.springframework.transaction.support.TransactionCallback;

 import org.springframework.transaction.support.TransactionCallbackWithoutResult;

 import org.springframework.transaction.support.TransactionTemplate;

 import com.xpw.dao.TradeDao;

 import com.xpw.service.TradeService;

 public class TradeServiceImpl implements TradeService {

     private TradeDao tradeDao;

     private TransactionTemplate transactionTemplate;

     public void setTradeDao(TradeDao tradeDao) {

         this.tradeDao = tradeDao;

     }

     public void setTransactionTemplate(TransactionTemplate transactionTemplate) {

         this.transactionTemplate = transactionTemplate;

     }

         //编程事务管理

     @Override

     public void trade(final int fromIdCard, final int toIdCard, final int money) {

         this.transactionTemplate.execute(new TransactionCallbackWithoutResult() {

             @Override

             protected void doInTransactionWithoutResult(TransactionStatus arg0) {

                 tradeDao.outputMoney(fromIdCard, money);

                 tradeDao.inputMoney(toIdCard, money);

             }

         });

     }

 }

beans.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:context="http://www.springframework.org/schema/context"

     xsi:schemaLocation="http://www.springframework.org/schema/beans

         http://www.springframework.org/schema/beans/spring-beans.xsd

         http://www.springframework.org/schema/context

         http://www.springframework.org/schema/context/spring-context.xsd">    

     <context:component-scan base-package="org.springframework.docs.test" />

     <context:property-placeholder location="jdbc.properties"/>    

     <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">

         <property name="driverClassName" value="${jdbc.driverClassName}"/>

         <property name="url" value="${jdbc.url}"/>

         <property name="username" value="${jdbc.username}"/>

         <property name="password" value="${jdbc.password}"/>

     </bean>

     <bean id="transactionTemplate" class="org.springframework.transaction.support.TransactionTemplate">

         <property name="transactionManager" ref="transactionManager"></property>

     </bean>

     <!-- 事务管理器 -->

     <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">

     </bean>

     <bean id="namedParameterJdbcTemplate" class="org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate">

         <constructor-arg ref="dataSource"></constructor-arg>

     </bean>

     <bean id="tradeDao" class="com.xpw.dao.impl.TradeDaoImpl">

         <property name="namedParameterJdbcTemplate" ref="namedParameterJdbcTemplate"/>

     </bean>

     <bean id="tradeService" class="com.xpw.service.impl.TradeServiceImpl">

         <property name="tradeDao" ref="tradeDao"></property>

         <property name="transactionTemplate" ref="transactionTemplate"></property>

     </bean>

 </beans>

其它的代码都没有变

结果：

mysql> select * from trademoney;

+--------+------+-------+

| idCard | name | money |

+--------+------+-------+

|      1 | xx   |   300 |

|      2 | ++   |   300 |

+--------+------+-------+

2 rows in set (0.00 sec)

从上面的结果可以知道，编程式事务管理已经成功了，在 B + 50 失败了，回回滚，所以 A 不会 - 50

2、声明式事务管理

使用annotation

service impl 层

 package com.xpw.service.impl;

 import org.springframework.transaction.annotation.Transactional;

 import org.springframework.transaction.support.TransactionTemplate;

 import com.xpw.dao.TradeDao;

 import com.xpw.service.TradeService;

 @Transactional

 public class TradeServiceImpl implements TradeService {

     private TradeDao tradeDao;

     private TransactionTemplate transactionTemplate;

     public void setTradeDao(TradeDao tradeDao) {

         this.tradeDao = tradeDao;

     }

     public void setTransactionTemplate(TransactionTemplate transactionTemplate) {

         this.transactionTemplate = transactionTemplate;

     }

     @Override

     public void trade(int fromIdCard, int toIdCard, int money) {

         this.tradeDao.outputMoney(fromIdCard, money);

         this.tradeDao.inputMoney(toIdCard, money);

     }

 }

beans.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:context="http://www.springframework.org/schema/context"

     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/context

         http://www.springframework.org/schema/context/spring-context.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">    

     <context:component-scan base-package="org.springframework.docs.test" />

     <context:property-placeholder location="jdbc.properties"/>    

     <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">

         <property name="driverClassName" value="${jdbc.driverClassName}"/>

         <property name="url" value="${jdbc.url}"/>

         <property name="username" value="${jdbc.username}"/>

         <property name="password" value="${jdbc.password}"/>

     </bean>

     <!-- 事务管理器 -->

     <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">

         <property name="dataSource" ref="dataSource"></property>

     </bean>

     <tx:annotation-driven transaction-manager="transactionManager"/>

     <bean id="namedParameterJdbcTemplate" class="org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate">

         <constructor-arg ref="dataSource"></constructor-arg>

     </bean>

     <bean id="tradeDao" class="com.xpw.dao.impl.TradeDaoImpl">

         <property name="namedParameterJdbcTemplate" ref="namedParameterJdbcTemplate"/>

     </bean>

     <bean id="tradeService" class="com.xpw.service.impl.TradeServiceImpl">

         <property name="tradeDao" ref="tradeDao"></property>

     </bean>

 </beans>

结果：

+--------+------+-------+

| idCard | name | money |

+--------+------+-------+

|      1 | xx   |   300 |

|      2 | ++   |   300 |

+--------+------+-------+

2 rows in set (0.00 sec)

此方式成功 添加了事务管理

使用xml 方式

service impl 层

 package com.xpw.service.impl;

 import com.xpw.dao.TradeDao;

 import com.xpw.service.TradeService;

 public class TradeServiceImpl implements TradeService {

     private TradeDao tradeDao;

     public void setTradeDao(TradeDao tradeDao) {

         this.tradeDao = tradeDao;

     }

     @Override

     public void trade(int fromIdCard, int toIdCard, int money) {

         this.tradeDao.outputMoney(fromIdCard, money);

         this.tradeDao.inputMoney(toIdCard, money);

     }

 }

beans.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:context="http://www.springframework.org/schema/context"

     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/context

         http://www.springframework.org/schema/context/spring-context.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">

     <context:component-scan base-package="org.springframework.docs.test" />

     <context:property-placeholder location="jdbc.properties" />

     <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"

         destroy-method="close">

         <property name="driverClassName" value="${jdbc.driverClassName}" />

         <property name="url" value="${jdbc.url}" />

         <property name="username" value="${jdbc.username}" />

         <property name="password" value="${jdbc.password}" />

     </bean>

     <!-- 事务管理器 -->

     <bean id="transactionManager"

         class="org.springframework.jdbc.datasource.DataSourceTransactionManager">

         <property name="dataSource" ref="dataSource"></property>

     </bean>

     <!-- 事务通知器 -->

     <tx:advice>

         <tx:attributes>

             <tx:method name="*" />

         </tx:attributes>

     </tx:advice>

     <!-- 事务切面 -->

     <aop:config>

         <!-- 事务切点 -->

         <aop:pointcut expression="execution(* com.xpw.service.*.*(..))" id="transactionPointcut"/>

         <aop:advisor advice-ref="transactionPointcut"/>

     </aop:config>

     <bean id="namedParameterJdbcTemplate"

         class="org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate">

         <constructor-arg ref="dataSource"></constructor-arg>

     </bean>

     <bean id="tradeDao" class="com.xpw.dao.impl.TradeDaoImpl">

         <property name="namedParameterJdbcTemplate" ref="namedParameterJdbcTemplate" />

     </bean>

     <bean id="tradeService" class="com.xpw.service.impl.TradeServiceImpl">

         <property name="tradeDao" ref="tradeDao"></property>

     </bean>

 </beans>

结果

mysql> select * from trademoney;

+--------+------+-------+

| idCard | name | money |

+--------+------+-------+

|      1 | xx   |   300 |

|      2 | ++   |   300 |

+--------+------+-------+

2 rows in set (0.00 sec)

五、总结

事务管理有编程式、声明式，本人推荐后者。因为前者，虽然实现了事务管理，但在一定程度上，非业务逻辑代码浸入了我们的业务逻辑代码，如果系统大型的话，也不可避免重复操作，代码看起来也不整洁了，也不方便后期维护。

【tip】转载请注明原文来自：http://www.cnblogs.com/chenmo-xpw/p/3949264.html

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