SpringBoot之事务管理Transactional

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

package com.hik.entity;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;

/**
 * 账户实体
 * @author jed
 *
 */
@Entity
@Table(name="t_account")
public class Account {

    @Id
    @GeneratedValue
    private Integer id;
    
    @Column(length=50)
    private String userName;
    
    private float balance;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public float getBalance() {
        return balance;
    }

    public void setBalance(float balance) {
        this.balance = balance;
    }
    
    
}

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

package com.hik.dao;

import org.springframework.data.jpa.repository.JpaRepository;

import com.hik.entity.Account;

/**
 *  账户Dao接口
 * @author jed
 *
 */
public interface AccountDao extends JpaRepository<Account, Integer>{
    
}

AccountService接口

package com.hik.service;

/**
 * 帐号Service接口
 * @author jed
 *
 */
public interface AccountService {

    public void transferAccounts(int fromUser,int toUser,float account);
}

AccountServiceImpl接口实现类

package com.hik.service.impl;

import javax.annotation.Resource;

import org.springframework.stereotype.Service;

import com.hik.dao.AccountDao;
import com.hik.entity.Account;
import com.hik.service.AccountService;

/**
 * 帐号Service实现类
 * @author jed
 *
 */
@Service("accountService")
public class AccountServiceImpl implements AccountService{

    @Resource
    private AccountDao accountDao;
    
    @Override
    public void transferAccounts(int fromUser, int toUser, float account) {
        Account fromUserAccount = accountDao.getOne(fromUser);
        fromUserAccount.setBalance(fromUserAccount.getBalance()-account);
        accountDao.save(fromUserAccount); // fromUser扣钱
        
        Account toUserAccount = accountDao.getOne(toUser);
        toUserAccount.setBalance(toUserAccount.getBalance()+account);
        accountDao.save(toUserAccount);// toUser加钱
    }

}

AccountController类

package com.hik.Controller;

import javax.annotation.Resource;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.hik.service.AccountService;

/**
 * 账户Controoler类
 * @author jed
 *
 */
@RestController
@RequestMapping("/account")
public class AccountController {
    
    @Resource
    private AccountService accountService;

    @RequestMapping("/transfer")
    public String transferAccounts() {
        try {
            accountService.transferAccounts(1, 2, 200);
            return "ok";
        }catch(Exception e) {
            return "no";
        }
    }
}

application.yml

server: 
    port: 80
    context-path: /

spring: 
    datasource: 
      driver-class-name: com.mysql.jdbc.Driver
      url: jdbc:mysql://localhost:3306/db_bank
      username: root
      password: passwd
    jpa: 
      hibernate:
        ddl-auto: update
      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 

package com.hik.service.impl;

import javax.annotation.Resource;

import org.springframework.stereotype.Service;

import com.hik.dao.AccountDao;
import com.hik.entity.Account;
import com.hik.service.AccountService;

/**
 * 帐号Service实现类
 * @author jed
 *
 */
@Service("accountService")
public class AccountServiceImpl implements AccountService{

    @Resource
    private AccountDao accountDao;
    
    @Override
    public void transferAccounts(int fromUser, int toUser, float account) {
        Account fromUserAccount = accountDao.getOne(fromUser);
        fromUserAccount.setBalance(fromUserAccount.getBalance()-account);
        accountDao.save(fromUserAccount); // fromUser扣钱
        
        Account toUserAccount = accountDao.getOne(toUser);
        toUserAccount.setBalance(toUserAccount.getBalance()+account);
        int zero =1/0;
        accountDao.save(toUserAccount);// toUser加钱
    }

}

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

package com.hik.service.impl;

import javax.annotation.Resource;
import javax.transaction.Transactional;

import org.springframework.stereotype.Service;

import com.hik.dao.AccountDao;
import com.hik.entity.Account;
import com.hik.service.AccountService;

/**
 * 帐号Service实现类
 * @author jed
 *
 */
@Service("accountService")
public class AccountServiceImpl implements AccountService{

    @Resource
    private AccountDao accountDao;
    
    @Transactional
    public void transferAccounts(int fromUser, int toUser, float account) {
        Account fromUserAccount = accountDao.getOne(fromUser);
        fromUserAccount.setBalance(fromUserAccount.getBalance()-account);
        accountDao.save(fromUserAccount); // fromUser扣钱
        
        Account toUserAccount = accountDao.getOne(toUser);
        toUserAccount.setBalance(toUserAccount.getBalance()+account);
        int zero =1/0;
        accountDao.save(toUserAccount);// toUser加钱
    }

}

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。