<dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.3.1</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>

spring:
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://localhost:3306/jdbctest?useSSL=true&useUnicode=true&characterEncoding=utf-8
    username: root
    password: 123

package demo.entity;

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.math.BigDecimal;

@TableName("acount")
@Data
@AllArgsConstructor
@NoArgsConstructor
public class Account {
    @TableId(type = IdType.AUTO)
    private Integer id;

    private String name;

    private BigDecimal money; 
}

package demo.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import demo.entity.Account;
import org.apache.ibatis.annotations.Mapper;

@Mapper
public interface AccountMapper extends BaseMapper<Account> {
}

package demo.service;

import com.baomidou.mybatisplus.extension.service.IService;
import demo.entity.Account;
import java.math.BigDecimal;

public interface AccountService extends IService<Account> {

    boolean transfer(String source, String target, BigDecimal money);
}

package demo.service.impl;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import demo.entity.Account;
import demo.mapper.AccountMapper;
import demo.service.AccountService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.math.BigDecimal;

@Service
public class AccountServiceImpl extends ServiceImpl<AccountMapper, Account> implements AccountService {
    @Autowired
    private AccountMapper accountMapper;

    private Integer i1;
    private Integer i2;

    public boolean transfer(String source, String target, BigDecimal money) {
        //獲取匯款方
        QueryWrapper<Account> wrapper1 = new QueryWrapper<>();
        wrapper1.eq("name", source);
        Account one1 = accountMapper.selectOne(wrapper1);

        QueryWrapper<Account> wrapper2 = new QueryWrapper<>();
        wrapper2.eq("name", target);
        Account one2 = accountMapper.selectOne(wrapper2);

        one1.setMoney(one1.getMoney().subtract(money)); //十進制減法
        i1 = accountMapper.updateById(one1);
        

        one2.setMoney(one2.getMoney().add(money)); //十進制加法
        i2 = accountMapper.updateById(one2);
        if (i1 > 0 && i2 > 0) {
            return true;
        }
        return false;
    }
}

package demo.controller;

import demo.service.AccountService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.math.BigDecimal;

@RestController
public class TestController {

    @Autowired
    private AccountService accountService;

    @RequestMapping("/test")
    public String test(){
        String result = null;
        boolean b = accountService.transfer("A", "B", BigDecimal.valueOf(700D));
        if(b){
            result = "轉(zhuǎn)賬成功!";
        } else {
            result = "轉(zhuǎn)賬異常!";
        }
        return result;
    }
}

package com.example.mabatistransaction.Service.impl;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.example.mabatistransaction.Mapper.AccountMapper;
import com.example.mabatistransaction.Service.AccountService;
import com.example.mabatistransaction.entity.Account;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.math.BigDecimal;

@Service
public class AccountServiceImpl implements AccountService {

    @Autowired
    private AccountMapper accountMapper;

    @Transactional
    @Override
    public boolean transferTo(String source, String target, BigDecimal money) {
        boolean isOK = false;

        //獲取匯款方
        QueryWrapper<Account> wrapper1 = new QueryWrapper<Account>();
        wrapper1.eq("name", source);
        Account sourcePerson = accountMapper.selectOne(wrapper1);

        //獲取收款方賬戶
        QueryWrapper<Account> wrapper2 = new QueryWrapper<Account>();
        wrapper2.eq("name", target);
        Account tatgetPerson = accountMapper.selectOne(wrapper2);

        //轉(zhuǎn)賬

        //源賬戶取出700
        sourcePerson.setMoney(sourcePerson.getMoney().subtract(money)); //進行十進制的減法
        int a = accountMapper.updateById(sourcePerson);

        //模擬異常
        int y = 1/0;

        //目標賬戶存入700
        tatgetPerson.setMoney(tatgetPerson.getMoney().add(money));  //進行十進制加法
        int b = accountMapper.updateById(tatgetPerson);

        //判斷是否成功
        if(a>0 && b>0){
            isOK=true;
        }

        return isOK;
    }
}