以前学ssh ssm都有事务管理service层通过applicationContext.xml配置，所有service方法都加上事务操作；
用来保证一致性，即service方法里的多个dao操作，要么同时成功，要么同时失败；
springboot下的话 一个@Transactional即可搞定；
我们这里搞一个实例，转账实例，A用户转账给B用户xx元
设计如下：
Account类
1 package com.hik.entity;
2
3 import javax.persistence.Column;
4 import javax.persistence.Entity;
5 import javax.persistence.GeneratedValue;
6 import javax.persistence.Id;
7 import javax.persistence.Table;
8
9 /**
10 * 账户实体
11 * @author jed
12 *
13 */
14 @Entity
15 @Table(name="t_account")
16 public class Account {
17
18 @Id
19 @GeneratedValue
20 private Integer id;
21
22 @Column(length=50)
23 private String userName;
24
25 private float balance;
26
27 public Integer getId() {
28 return id;
29 }
30
31 public void setId(Integer id) {
32 this.id = id;
33 }
34
35 public String getUserName() {
36 return userName;
37 }
38
39 public void setUserName(String userName) {
40 this.userName = userName;
41 }
42
43 public float getBalance() {
44 return balance;
45 }
46
47 public void setBalance(float balance) {
48 this.balance = balance;
49 }
50
51
52 }
id 编号 userName用户名 balance余额
运行启动类，数据库里我们加两个数据
新建AccountDao接口
1 package com.hik.dao;
2
3 import org.springframework.data.jpa.repository.JpaRepository;
4
5 import com.hik.entity.Account;
6
7 /**
8 * 账户Dao接口
9 * @author jed
10 *
11 */
12 public interface AccountDao extends JpaRepository<Account, Integer>{
13
14 }
AccountService接口
1 package com.hik.service;
2
3 /**
4 * 帐号Service接口
5 * @author jed
6 *
7 */
8 public interface AccountService {
9
10 public void transferAccounts(int fromUser,int toUser,float account);
11 }
AccountServiceImpl接口实现类
1 package com.hik.service.impl;
2
3 import javax.annotation.Resource;
4
5 import org.springframework.stereotype.Service;
6
7 import com.hik.dao.AccountDao;
8 import com.hik.entity.Account;
9 import com.hik.service.AccountService;
10
11 /**
12 * 帐号Service实现类
13 * @author jed
14 *
15 */
16 @Service("accountService")
17 public class AccountServiceImpl implements AccountService{
18
19 @Resource
20 private AccountDao accountDao;
21
22 @Override
23 public void transferAccounts(int fromUser, int toUser, float account) {
24 Account fromUserAccount = accountDao.getOne(fromUser);
25 fromUserAccount.setBalance(fromUserAccount.getBalance()-account);
26 accountDao.save(fromUserAccount); // fromUser扣钱
27
28 Account toUserAccount = accountDao.getOne(toUser);
29 toUserAccount.setBalance(toUserAccount.getBalance()+account);
30 accountDao.save(toUserAccount);// toUser加钱
31 }
32
33 }
AccountController类
1 package com.hik.Controller;
2
3 import javax.annotation.Resource;
4
5 import org.springframework.web.bind.annotation.RequestMapping;
6 import org.springframework.web.bind.annotation.RestController;
7
8 import com.hik.service.AccountService;
9
10 /**
11 * 账户Controoler类
12 * @author jed
13 *
14 */
15 @RestController
16 @RequestMapping("/account")
17 public class AccountController {
18
19 @Resource
20 private AccountService accountService;
21
22 @RequestMapping("/transfer")
23 public String transferAccounts() {
24 try {
25 accountService.transferAccounts(1, 2, 200);
26 return "ok";
27 }catch(Exception e) {
28 return "no";
29 }
30 }
31 }
application.yml
1 server: 2 port: 80 3 context-path: / 4 5 spring: 6 datasource: 7 driver-class-name: com.mysql.jdbc.Driver 8 url: jdbc:mysql://localhost:3306/db_bank 9 username: root 10 password: passwd 11 jpa: 12 hibernate: 13 ddl-auto: update 14 show-sql: true
我们执行启动类
浏览器输入：http://localhost/account/transfer
运行OK
查看数据库表
OK 我们先把数据恢复到700 300
现在我们把service层方法改下
1 package com.hik.service.impl;
2
3 import javax.annotation.Resource;
4
5 import org.springframework.stereotype.Service;
6
7 import com.hik.dao.AccountDao;
8 import com.hik.entity.Account;
9 import com.hik.service.AccountService;
10
11 /**
12 * 帐号Service实现类
13 * @author jed
14 *
15 */
16 @Service("accountService")
17 public class AccountServiceImpl implements AccountService{
18
19 @Resource
20 private AccountDao accountDao;
21
22 @Override
23 public void transferAccounts(int fromUser, int toUser, float account) {
24 Account fromUserAccount = accountDao.getOne(fromUser);
25 fromUserAccount.setBalance(fromUserAccount.getBalance()-account);
26 accountDao.save(fromUserAccount); // fromUser扣钱
27
28 Account toUserAccount = accountDao.getOne(toUser);
29 toUserAccount.setBalance(toUserAccount.getBalance()+account);
30 int zero =1/0;
31 accountDao.save(toUserAccount);// toUser加钱
32 }
33
34 }
这时候 扣钱dao能执行成功 加钱操作执行不了了 因为前面会报错
我们重启启动类
浏览器输入：http://localhost/account/transfer
运行NO
查看数据库
这时候 钱扣了 但是 没加钱 导致了数据不一致性
这时候 我们需要用上事务
在service方法上加上@Transactional即可
1 package com.hik.service.impl;
2
3 import javax.annotation.Resource;
4 import javax.transaction.Transactional;
5
6 import org.springframework.stereotype.Service;
7
8 import com.hik.dao.AccountDao;
9 import com.hik.entity.Account;
10 import com.hik.service.AccountService;
11
12 /**
13 * 帐号Service实现类
14 * @author jed
15 *
16 */
17 @Service("accountService")
18 public class AccountServiceImpl implements AccountService{
19
20 @Resource
21 private AccountDao accountDao;
22
23 @Transactional
24 public void transferAccounts(int fromUser, int toUser, float account) {
25 Account fromUserAccount = accountDao.getOne(fromUser);
26 fromUserAccount.setBalance(fromUserAccount.getBalance()-account);
27 accountDao.save(fromUserAccount); // fromUser扣钱
28
29 Account toUserAccount = accountDao.getOne(toUser);
30 toUserAccount.setBalance(toUserAccount.getBalance()+account);
31 int zero =1/0;
32 accountDao.save(toUserAccount);// toUser加钱
33 }
34
35 }
我们恢复下数据700 300
然后再重启启动类，
浏览器输入：http://localhost/account/transfer
运行NO
但是数据库数据没变化 说明启动作用了。
OK，保证事务一致性，方法上加Transactional即可。
原文地址：https://www.cnblogs.com/jedjia/p/transactional.html
时间： 2024-10-08 10:53:35