使用MyBatisPlus+Spring实现声明式事务

前言：

1.springboot使用事务需要引入sprint-tx,但是在结合mybatisplus时，mybatis-plus已经代为引入了，

2.在springboot的启动类或者某个@Configuration上，加上@EnableTransactionManagent开启事务的支持

3.在service中使用@Transactional就可以使用事务了，@Transactional添加在方法中，方法支持事务，如果将@Transactional添加在类上，则整个类的所有方法都默认支持事务

4.@Transactional默认回滚的是RuntimeExcaption，如果不是抛出的RuntimeException则不会被回滚，（在spring框架下，所有的异常都被org.springwork重写为RuntimeExcetpion）

5.@Transactional(rollbackFor=Excetpion.class)，在@Transactional注解中如果不配置rollbackFor属性,那么事物只会在遇到RuntimeException的时候才会回滚,加上rollbackFor=Exception.class,可以让事物在遇到非运行时异常时也回滚

6.使用try catch捕捉异常进行异常处理，除了throw异常，即抛出一场，才会回滚，否则不会触发回滚

步骤一:在pom.xml中导入依赖

导入MyBatisPlus相关依赖

            <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>

步骤二:application中配置数据源

spring:
  datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://10.211.55.2:3306/jdbctest?useSSL=true&useUnicode=true&characterEncoding=utf-8
    username: root
    password: Aa123123.

步骤三: 创建实体类，service，mapper和controller

3.1创建实体类

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;
}

3.2创建Mapper```java

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> {
}

3.3创建Service

AccountService

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);
}

AccountServiceImpl

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;

    //开启事务
    @Transactional
    public boolean transfer(String source, String target, BigDecimal money) {
        //获取汇款方
        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)); //十进制减法
        i1 = accountMapper.updateById(one1);
        //模拟转账异常
        int a=1/0;

        one2.setMoney(one2.getMoney().add(money)); //十进制加法
        i2 = accountMapper.updateById(one2);
        if (i1 > 0 && i2 > 0) {
            return true;
        }
        return false;
    }
}

3.4创建TestController

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(700));
        if(b){
            result = "转账成功!";
        } else {
            result = "转账异常!";
        }
        return result;
    }
}