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(32),money int); 插入两条记录 insert into countmoney(name,money)values(‘xx‘,300); insert into countmoney(name,money)values(‘++‘,300); 结果 select * from countmoney;
+--------+------+-------+
| idCard | name | money |
+--------+------+-------+
| 1 | xx | 300 |
| 2 | ++ | 300 |
+--------+------+-------+
（4）、代码
model 层
1 package com.xpw.model;
2
3 public class Count {
4 private int idCard;
5 private String name;
6 private int money;
7
8 public Count(){
9
10 }
11
12 public int getIdCard() {
13 return idCard;
14 }
15 public void setIdCard(int idCard) {
16 this.idCard = idCard;
17 }
18 public String getName() {
19 return name;
20 }
21 public void setName(String name) {
22 this.name = name;
23 }
24 public int getMoney() {
25 return money;
26 }
27 public void setMoney(int money) {
28 this.money = money;
29 }
30
31 }
dao 层
1 package com.xpw.dao;
2
3 public interface TradeDao {
4
5 public void outputMoney(int idCard, int money);
6
7 public void inputMoney(int idCard, int money);
8 }
dao impl 层
1 package com.xpw.dao.impl;
2
3 import org.springframework.jdbc.core.JdbcTemplate;
4 import org.springframework.jdbc.core.namedparam.MapSqlParameterSource;
5 import org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate;
6 import org.springframework.jdbc.core.namedparam.SqlParameterSource;
7
8 import com.xpw.dao.TradeDao;
9
10 public class TradeDaoImpl implements TradeDao {
11
12 private NamedParameterJdbcTemplate namedParameterJdbcTemplate;
13
14 public void setNamedParameterJdbcTemplate(
15 NamedParameterJdbcTemplate namedParameterJdbcTemplate) {
16 this.namedParameterJdbcTemplate = namedParameterJdbcTemplate;
17 }
18
19 @Override
20 public void outputMoney(int idCard, int count) {
21 String sql = "update trademoney set money = money -:count where idCard = :idCard";
22 MapSqlParameterSource param = new MapSqlParameterSource();
23 param.addValue("count", count);
24 param.addValue("idCard", idCard);
25 this.namedParameterJdbcTemplate.update(sql, param);
26 }
27
28 @Override
29 public void inputMoney(int idCard, int count) {
30 //我们故意在此出错，抛出异常，让 B + 50失败
31 System.out.println(1/0);
32 String sql = "update trademoney set money = money + :count where idCard = :idCard";
33 MapSqlParameterSource param = new MapSqlParameterSource();
34 param.addValue("count", count);
35 param.addValue("idCard", idCard);
36 this.namedParameterJdbcTemplate.update(sql, param);
37 }
38 }
Service层
1 package com.xpw.service;
2
3 public interface TradeService {
4 public void trade(int fromIdCard, int toIdCard, int money);
5 }
Service impl 层
1 package com.xpw.service.impl;
2
3 import com.xpw.dao.TradeDao;
4 import com.xpw.service.TradeService;
5
6 public class TradeServiceImpl implements TradeService {
7
8 private TradeDao tradeDao;
9
10 public void setTradeDao(TradeDao tradeDao) {
11 this.tradeDao = tradeDao;
12 }
13
14 @Override
15 public void trade(int fromIdCard, int toIdCard, int money) {
16 this.tradeDao.outputMoney(fromIdCard, money);
17 this.tradeDao.inputMoney(toIdCard, money);
18 }
19 }
（5）文件配置信息
beans.xml
1 <?xml version="1.0" encoding="UTF-8"?>
2 <beans xmlns="http://www.springframework.org/schema/beans"
3 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4 xmlns:context="http://www.springframework.org/schema/context"
5 xsi:schemaLocation="http://www.springframework.org/schema/beans
6 http://www.springframework.org/schema/beans/spring-beans.xsd
7 http://www.springframework.org/schema/context
8 http://www.springframework.org/schema/context/spring-context.xsd">
9
10 <context:component-scan base-package="org.springframework.docs.test" />
11 <context:property-placeholder location="jdbc.properties"/>
12
13 <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
14 <property name="driverClassName" value="${jdbc.driverClassName}"/>
15 <property name="url" value="${jdbc.url}"/>
16 <property name="username" value="${jdbc.username}"/>
17 <property name="password" value="${jdbc.password}"/>
18 </bean>
19
20 <bean id="namedParameterJdbcTemplate" class="org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate">
21 <constructor-arg ref="dataSource"></constructor-arg>
22 </bean>
23
24 <bean id="tradeDao" class="com.xpw.dao.impl.TradeDaoImpl">
25 <property name="namedParameterJdbcTemplate" ref="namedParameterJdbcTemplate"/>
26 </bean>
27
28 <bean id="tradeService" class="com.xpw.service.impl.TradeServiceImpl">
29 <property name="tradeDao" ref="tradeDao"></property>
30 </bean>
31 </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）
1 package com.xpw.service.impl;
2
3 import org.springframework.transaction.TransactionStatus;
4 import org.springframework.transaction.support.TransactionCallback;
5 import org.springframework.transaction.support.TransactionCallbackWithoutResult;
6 import org.springframework.transaction.support.TransactionTemplate;
7
8 import com.xpw.dao.TradeDao;
9 import com.xpw.service.TradeService;
10
11 public class TradeServiceImpl implements TradeService {
12
13 private TradeDao tradeDao;
14 private TransactionTemplate transactionTemplate;
15
16 public void setTradeDao(TradeDao tradeDao) {
17 this.tradeDao = tradeDao;
18 }
19
20 public void setTransactionTemplate(TransactionTemplate transactionTemplate) {
21 this.transactionTemplate = transactionTemplate;
22 }
23
24 //编程事务管理
25 @Override
26 public void trade(final int fromIdCard, final int toIdCard, final int money) {
27 this.transactionTemplate.execute(new TransactionCallbackWithoutResult() {
28
29 @Override
30 protected void doInTransactionWithoutResult(TransactionStatus arg0) {
31 tradeDao.outputMoney(fromIdCard, money);
32 tradeDao.inputMoney(toIdCard, money);
33 }
34 });
35 }
36 }
beans.xml
1 <?xml version="1.0" encoding="UTF-8"?>
2 <beans xmlns="http://www.springframework.org/schema/beans"
3 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4 xmlns:context="http://www.springframework.org/schema/context"
5 xsi:schemaLocation="http://www.springframework.org/schema/beans
6 http://www.springframework.org/schema/beans/spring-beans.xsd
7 http://www.springframework.org/schema/context
8 http://www.springframework.org/schema/context/spring-context.xsd">
9
10 <context:component-scan base-package="org.springframework.docs.test" />
11 <context:property-placeholder location="jdbc.properties"/>
12
13 <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
14 <property name="driverClassName" value="${jdbc.driverClassName}"/>
15 <property name="url" value="${jdbc.url}"/>
16 <property name="username" value="${jdbc.username}"/>
17 <property name="password" value="${jdbc.password}"/>
18 </bean>
19
20 <bean id="transactionTemplate" class="org.springframework.transaction.support.TransactionTemplate">
21 <property name="transactionManager" ref="transactionManager"></property>
22 </bean>
23 <!-- 事务管理器 -->
24 <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
25 </bean>
26
27 <bean id="namedParameterJdbcTemplate" class="org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate">
28 <constructor-arg ref="dataSource"></constructor-arg>
29 </bean>
30
31 <bean id="tradeDao" class="com.xpw.dao.impl.TradeDaoImpl">
32 <property name="namedParameterJdbcTemplate" ref="namedParameterJdbcTemplate"/>
33 </bean>
34
35 <bean id="tradeService" class="com.xpw.service.impl.TradeServiceImpl">
36 <property name="tradeDao" ref="tradeDao"></property>
37 <property name="transactionTemplate" ref="transactionTemplate"></property>
38 </bean>
39 </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
1 package com.xpw.service.impl;
2
3
4 import org.springframework.transaction.annotation.Transactional;
5
6 import org.springframework.transaction.support.TransactionTemplate;
7
8 import com.xpw.dao.TradeDao;
9 import com.xpw.service.TradeService;
10
11 @Transactional
12 public class TradeServiceImpl implements TradeService {
13
14 private TradeDao tradeDao;
15 private TransactionTemplate transactionTemplate;
16
17 public void setTradeDao(TradeDao tradeDao) {
18 this.tradeDao = tradeDao;
19 }
20
21 public void setTransactionTemplate(TransactionTemplate transactionTemplate) {
22 this.transactionTemplate = transactionTemplate;
23 }
24
25 @Override
26 public void trade(int fromIdCard, int toIdCard, int money) {
27 this.tradeDao.outputMoney(fromIdCard, money);
28 this.tradeDao.inputMoney(toIdCard, money);
29 }
30
31 }
beans.xml
1 <?xml version="1.0" encoding="UTF-8"?>
2 <beans xmlns="http://www.springframework.org/schema/beans"
3 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4 xmlns:context="http://www.springframework.org/schema/context"
5 xmlns:aop = "http://www.springframework.org/schema/aop"
6 xmlns:tx="http://www.springframework.org/schema/tx"
7 xsi:schemaLocation="http://www.springframework.org/schema/beans
8 http://www.springframework.org/schema/beans/spring-beans.xsd
9 http://www.springframework.org/schema/context
10 http://www.springframework.org/schema/context/spring-context.xsd
11 http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
12 http://www.springframework.org/schema/aop
13 http://www.springframework.org/schema/aop/spring-aop.xsd">
14
15 <context:component-scan base-package="org.springframework.docs.test" />
16 <context:property-placeholder location="jdbc.properties"/>
17
18 <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
19 <property name="driverClassName" value="${jdbc.driverClassName}"/>
20 <property name="url" value="${jdbc.url}"/>
21 <property name="username" value="${jdbc.username}"/>
22 <property name="password" value="${jdbc.password}"/>
23 </bean>
24
25 <!-- 事务管理器 -->
26 <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
27 <property name="dataSource" ref="dataSource"></property>
28 </bean>
29
30 <tx:annotation-driven transaction-manager="transactionManager"/>
31
32 <bean id="namedParameterJdbcTemplate" class="org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate">
33 <constructor-arg ref="dataSource"></constructor-arg>
34 </bean>
35
36 <bean id="tradeDao" class="com.xpw.dao.impl.TradeDaoImpl">
37 <property name="namedParameterJdbcTemplate" ref="namedParameterJdbcTemplate"/>
38 </bean>
39
40 <bean id="tradeService" class="com.xpw.service.impl.TradeServiceImpl">
41 <property name="tradeDao" ref="tradeDao"></property>
42 </bean>
43 </beans>
结果： +--------+------+-------+ | idCard | name | money | +--------+------+-------+ | 1 | xx | 300 | | 2 | ++ | 300 | +--------+------+-------+ 2 rows in set (0.00 sec) 由此，此方式成功 添加了事务管理
使用xml 方式
service impl 层
1 package com.xpw.service.impl;
2
3 import com.xpw.dao.TradeDao;
4 import com.xpw.service.TradeService;
5
6 public class TradeServiceImpl implements TradeService {
7
8 private TradeDao tradeDao;
9
10 public void setTradeDao(TradeDao tradeDao) {
11 this.tradeDao = tradeDao;
12 }
13
14
15 @Override
16 public void trade(int fromIdCard, int toIdCard, int money) {
17 this.tradeDao.outputMoney(fromIdCard, money);
18 this.tradeDao.inputMoney(toIdCard, money);
19 }
20 }
beans.xml
1 <?xml version="1.0" encoding="UTF-8"?>
2 <beans xmlns="http://www.springframework.org/schema/beans"
3 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
4 xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"
5 xsi:schemaLocation="http://www.springframework.org/schema/beans
6 http://www.springframework.org/schema/beans/spring-beans.xsd
7 http://www.springframework.org/schema/context
8 http://www.springframework.org/schema/context/spring-context.xsd
9 http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
10 http://www.springframework.org/schema/aop
11 http://www.springframework.org/schema/aop/spring-aop.xsd">
12
13 <context:component-scan base-package="org.springframework.docs.test" />
14 <context:property-placeholder location="jdbc.properties" />
15
16 <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
17 destroy-method="close">
18 <property name="driverClassName" value="${jdbc.driverClassName}" />
19 <property name="url" value="${jdbc.url}" />
20 <property name="username" value="${jdbc.username}" />
21 <property name="password" value="${jdbc.password}" />
22 </bean>
23
24 <!-- 事务管理器 -->
25 <bean id="transactionManager"
26 class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
27 <property name="dataSource" ref="dataSource"></property>
28 </bean>
29
30 <!-- 事务通知器 -->
31 <tx:advice>
32 <tx:attributes>
33 <tx:method name="*" />
34 </tx:attributes>
35 </tx:advice>
36 <!-- 事务切面 -->
37 <aop:config>
38 <!-- 事务切点 -->
39 <aop:pointcut expression="execution(* com.xpw.service.*.*(..))" id="transactionPointcut"/>
40 <aop:advisor advice-ref="transactionPointcut"/>
41 </aop:config>
42
43 <bean id="namedParameterJdbcTemplate"
44 class="org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate">
45 <constructor-arg ref="dataSource"></constructor-arg>
46 </bean>
47
48 <bean id="tradeDao" class="com.xpw.dao.impl.TradeDaoImpl">
49 <property name="namedParameterJdbcTemplate" ref="namedParameterJdbcTemplate" />
50 </bean>
51
52 <bean id="tradeService" class="com.xpw.service.impl.TradeServiceImpl">
53 <property name="tradeDao" ref="tradeDao"></property>
54 </bean>
55 </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
时间： 2024-11-09 03:44:10