RocketMQ 实战：模拟电商网站场景综合案例（六）

一、RocketMQ 实战 ：项目公共类介绍

1、ID 生成器 ：IDWorker：Twitter 雪花算法。

在 shop-common 工程模块中，IDWorker.java 是 ID 生成器公共类，运用 Twitter 雪花算法，自动生成项目 ID，而不会存在重复现象。

package com.itheima.utils;

public class IDWorker {

    /**
     * 起始的时间戳
     */
    private final static long START_STMP = 1480166465631L;

    /**
     * 每一部分占用的位数
     */
    private final static long SEQUENCE_BIT = 12; //序列号占用的位数
    private final static long MACHINE_BIT = 5;   //机器标识占用的位数
    private final static long DATACENTER_BIT = 5;//数据中心占用的位数

    /**
     * 每一部分的最大值
     */
    private final static long MAX_DATACENTER_NUM = -1L ^ (-1L << DATACENTER_BIT);
    private final static long MAX_MACHINE_NUM = -1L ^ (-1L << MACHINE_BIT);
    private final static long MAX_SEQUENCE = -1L ^ (-1L << SEQUENCE_BIT);

    /**
     * 每一部分向左的位移
     */
    private final static long MACHINE_LEFT = SEQUENCE_BIT;
    private final static long DATACENTER_LEFT = SEQUENCE_BIT + MACHINE_BIT;
    private final static long TIMESTMP_LEFT = DATACENTER_LEFT + DATACENTER_BIT;

    private long datacenterId;  //数据中心
    private long machineId;     //机器标识
    private long sequence = 0L; //序列号
    private long lastStmp = -1L;//上一次时间戳

    public IDWorker(long datacenterId, long machineId) {
        if (datacenterId > MAX_DATACENTER_NUM || datacenterId < 0) {
            throw new IllegalArgumentException("datacenterId can't be greater than MAX_DATACENTER_NUM or less than 0");
        }
        if (machineId > MAX_MACHINE_NUM || machineId < 0) {
            throw new IllegalArgumentException("machineId can't be greater than MAX_MACHINE_NUM or less than 0");
        }
        this.datacenterId = datacenterId;
        this.machineId = machineId;
    }

    /**
     * 产生下一个ID
     *
     * @return
     */
    public synchronized long nextId() {
        long currStmp = getNewstmp();
        if (currStmp < lastStmp) {
            throw new RuntimeException("Clock moved backwards.  Refusing to generate id");
        }

        if (currStmp == lastStmp) {
            //相同毫秒内，序列号自增
            sequence = (sequence + 1) & MAX_SEQUENCE;
            //同一毫秒的序列数已经达到最大
            if (sequence == 0L) {
                currStmp = getNextMill();
            }
        } else {
            //不同毫秒内，序列号置为0
            sequence = 0L;
        }

        lastStmp = currStmp;

        return (currStmp - START_STMP) << TIMESTMP_LEFT //时间戳部分
                | datacenterId << DATACENTER_LEFT       //数据中心部分
                | machineId << MACHINE_LEFT             //机器标识部分
                | sequence;                             //序列号部分
    }

    private long getNextMill() {
        long mill = getNewstmp();
        while (mill <= lastStmp) {
            mill = getNewstmp();
        }
        return mill;
    }

    private long getNewstmp() {
        return System.currentTimeMillis();
    }

    public static void main(String[] args) {
        IDWorker idWorker = new IDWorker(2, 3);
        for (int i = 0; i < 10; i++) {
            System.out.println(idWorker.nextId());
        }
    }

}

2、异常处理类：

在 shop-common 工程模块中，
CustomerException.java ：自定义异常公共类，CastException.java ：异常抛出公共类。

package com.itheima.exception;

import com.itheima.constant.ShopCode;
import lombok.extern.slf4j.Slf4j;

/**
 * 异常抛出类
 */
@Slf4j
public class CastException {
    public static void cast(ShopCode shopCode) {
        log.error(shopCode.toString());
        throw new CustomerException(shopCode);
    }
}

package com.itheima.exception;

import com.itheima.constant.ShopCode;

/**
 * 自定义异常
 */
public class CustomerException extends RuntimeException{

    private ShopCode shopCode;

    public CustomerException(ShopCode shopCode) {
        this.shopCode = shopCode;
    }
}

3、常量类 ： ShopCode：系统状态类

在 shop-common 工程模块中，ShopCode.java ：是系统状态公共类。

package com.itheima.constant;

/**
 * @author Think
 */

public enum ShopCode {
    //正确
    SHOP_SUCCESS(true, 1, "正确"),
    //错误
    SHOP_FAIL(false, 0, "错误"),

    //付款
    SHOP_USER_MONEY_PAID(true, 1, "付款"),
    //退款
    SHOP_USER_MONEY_REFUND(true, 2, "退款"),
    //订单未确认
    SHOP_ORDER_NO_CONFIRM(false, 0, "订单未确认"),
    //订单已确认
    SHOP_ORDER_CONFIRM(true, 1, "订单已经确认"),
    //订单已取消
    SHOP_ORDER_CANCEL(false, 2, "订单已取消"),
    //订单已取消
    SHOP_ORDER_INVALID(false, 3, "订单无效"),
    //订单已取消
    SHOP_ORDER_RETURNED(false, 4, "订单已退货"),
    //订单已付款
    SHOP_ORDER_PAY_STATUS_NO_PAY(true,0,"订单未付款"),
    //订单已付款
    SHOP_ORDER_PAY_STATUS_PAYING(true,1,"订单正在付款"),
    //订单已付款
    SHOP_ORDER_PAY_STATUS_IS_PAY(true,2,"订单已付款"),
    //消息正在处理
    SHOP_MQ_MESSAGE_STATUS_PROCESSING(true, 0, "消息正在处理"),
    //消息处理成功
    SHOP_MQ_MESSAGE_STATUS_SUCCESS(true, 1, "消息处理成功"),
    //消息处理失败
    SHOP_MQ_MESSAGE_STATUS_FAIL(false, 2, "消息处理失败"),
    //请求参数有误
    SHOP_REQUEST_PARAMETER_VALID(false, -1, "请求参数有误"),
    //优惠券已经使用
    SHOP_COUPON_ISUSED(true, 1, "优惠券已经使用"),
    //优惠券未使用
    SHOP_COUPON_UNUSED(false, 0, "优惠券未使用"),
    //快递运费不正确
    SHOP_ORDER_STATUS_UPDATE_FAIL(false, 10001, "订单状态修改失败"),
    //快递运费不正确
    SHOP_ORDER_SHIPPINGFEE_INVALID(false, 10002, "订单运费不正确"),
    //订单总价格不合法
    SHOP_ORDERAMOUNT_INVALID(false, 10003, "订单总价格不正确"),
    //订单保存失败
    SHOP_ORDER_SAVE_ERROR(false, 10004, "订单保存失败"),
    //订单确认失败
    SHOP_ORDER_CONFIRM_FAIL(false, 10005, "订单确认失败"),
    //商品不存在
    SHOP_GOODS_NO_EXIST(false, 20001, "商品不存在"),
    //订单价格非法
    SHOP_GOODS_PRICE_INVALID(false, 20002, "商品价格非法"),
    //商品库存不足
    SHOP_GOODS_NUM_NOT_ENOUGH(false, 20003, "商品库存不足"),
    //扣减库存失败
    SHOP_REDUCE_GOODS_NUM_FAIL(false, 20004, "扣减库存失败"),
    //库存记录为空
    SHOP_REDUCE_GOODS_NUM_EMPTY(false, 20005, "扣减库存失败"),
    //用户账号不能为空
    SHOP_USER_IS_NULL(false, 30001, "用户账号不能为空"),
    //用户信息不存在
    SHOP_USER_NO_EXIST(false, 30002, "用户不存在"),
    //余额扣减失败
    SHOP_USER_MONEY_REDUCE_FAIL(false, 30003, "余额扣减失败"),
    //已经退款
    SHOP_USER_MONEY_REFUND_ALREADY(true, 30004, "订单已经退过款"),
    //优惠券不不存在
    SHOP_COUPON_NO_EXIST(false, 40001, "优惠券不存在"),
    //优惠券不合法
    SHOP_COUPON_INVALIED(false, 40002, "优惠券不合法"),
    //优惠券使用失败
    SHOP_COUPON_USE_FAIL(false, 40003, "优惠券使用失败"),
    //余额不能小于0
    SHOP_MONEY_PAID_LESS_ZERO(false, 50001, "余额不能小于0"),
    //余额非法
    SHOP_MONEY_PAID_INVALID(false, 50002, "余额非法"),
    //Topic不能为空
    SHOP_MQ_TOPIC_IS_EMPTY(false, 60001, "Topic不能为空"),
    //消息体不能为空
    SHOP_MQ_MESSAGE_BODY_IS_EMPTY(false, 60002, "消息体不能为空"),
    //消息发送失败
    SHOP_MQ_SEND_MESSAGE_FAIL(false,60003,"消息发送失败"),
    //支付订单未找到
    SHOP_PAYMENT_NOT_FOUND(false,70001,"支付订单未找到"),
    //支付订单已支付
    SHOP_PAYMENT_IS_PAID(false,70002,"支付订单已支付"),
    //订单付款失败
    SHOP_PAYMENT_PAY_ERROR(false,70002,"订单支付失败");


    Boolean success;
    Integer code;
    String message;

    ShopCode() {

    }

    ShopCode(Boolean success, Integer code, String message) {
        this.success = success;
        this.code = code;
        this.message = message;
    }

    public Boolean getSuccess() {
        return success;
    }

    public void setSuccess(Boolean success) {
        this.success = success;
    }

    public Integer getCode() {
        return code;
    }

    public void setCode(Integer code) {
        this.code = code;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    @Override
    public String toString() {
        return "ShopCode{" +
                "success=" + success +
                ", code=" + code +
                ", message='" + message + '\'' +
                '}';
    }
}

4、响应实体类 ：Result：封装响应状态和响应信息

在 shop-pojo 工程模块中，Result.java ：是封装响应状态和响应信息的公共类。

package com.itheima.entity;

import java.io.Serializable;

/**
 * 结果实体类
 */
public class Result implements Serializable {
    private Boolean success;
    private String message;

    public Result() {
    }

    public Result(Boolean success, String message) {
        this.success = success;
        this.message = message;
    }

    public Boolean getSuccess() {
        return success;
    }

    public void setSuccess(Boolean success) {
        this.success = success;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    @Override
    public String toString() {
        return "Result{" +
                "success=" + success +
                ", message='" + message + '\'' +
                '}';
    }
}

二、RocketMQ 实战：模拟电商网站场景综合案例 – 下单功能时序图

三、RocketMQ 实战：下单接口定义和编码步骤分析

1、下单基本流程：接口定义 IOrderService.java

在 shop-api 工程模块中，创建 IOrderService.java 下单接口类。

package com.itheima.api;

import com.itheima.entity.Result;
import com.itheima.shop.pojo.TradeOrder;

public interface IOrderService {

    /**
     * 下单接口
     * @param order
     * @return
     */
    public Result confirmOrder(TradeOrder order);

}

2、下单基本流程：业务类实现 OrderServiceImpl.java

在 shop-order-service 工程模块中，创建 OrderServiceImpl.java 业务实现类。
基本框架如下：

@Slf4j
@Component
@Service(interfaceClass = IOrderService.class)
public class OrderServiceImpl implements IOrderService {

    @Override
    public Result confirmOrder(TradeOrder order) {
        //1.校验订单
       
        //2.生成预订单
       
        try {
            //3.扣减库存
            
            //4.扣减优惠券
           
            //5.使用余额
           
            //6.确认订单
            
            //7.返回成功状态
           
        } catch (Exception e) {
            //1.确认订单失败,发送消息
            
            //2.返回失败状态
        }

    }
}

四、RocketMQ 实战：模拟电商网站场景综合案例–校验订单流程分析图

五、RocketMQ 实战：模拟电商网站场景综合案例–校验订单实现

1、在 shop-order-service 工程模块中，创建 OrderServiceImpl.java 下单业务类，

完成 订单校验方法。

package com.itheima.shop.service;

import com.alibaba.dubbo.config.annotation.Reference;
import com.alibaba.dubbo.config.annotation.Service;
import com.alibaba.fastjson.JSON;
import com.itheima.api.ICouponService;
import com.itheima.api.IGoodsService;
import com.itheima.api.IOrderService;
import com.itheima.api.IUserService;
import com.itheima.constant.ShopCode;
import com.itheima.entity.MQEntity;
import com.itheima.entity.Result;
import com.itheima.exception.CastException;
import com.itheima.shop.mapper.TradeOrderMapper;
import com.itheima.shop.pojo.*;
import com.itheima.utils.IDWorker;
import lombok.extern.slf4j.Slf4j;
import org.apache.rocketmq.client.exception.MQBrokerException;
import org.apache.rocketmq.client.exception.MQClientException;
import org.apache.rocketmq.common.message.Message;
import org.apache.rocketmq.remoting.exception.RemotingException;
import org.apache.rocketmq.spring.core.RocketMQTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

import java.math.BigDecimal;
import java.util.Date;

@Slf4j
@Component
@Service(interfaceClass = IOrderService.class)
public class OrderServiceImpl implements IOrderService {


    @Reference
    private IGoodsService goodsService;

    @Reference
    private IUserService userService;

    @Override
    public Result confirmOrder(TradeOrder order) {
        //1.校验订单
        checkOrder(order);
        //2.生成预订单
       
        try {
            //3.扣减库存
     
            //4.扣减优惠券
     
            //5.使用余额

            //6.确认订单
          
            //7.返回成功状态
            
        } catch (Exception e) {
            //1.确认订单失败,发送消息
    

            //2.返回订单确认失败消息
     
            return null;
        }
    }


    /**
     * 校验订单
     *
     * @param order
     */
    private void checkOrder(TradeOrder order) {
        //1.校验订单是否存在
        if (order == null) {
            CastException.cast(ShopCode.SHOP_ORDER_INVALID);
        }
        //2.校验订单中的商品是否存在
        TradeGoods goods = goodsService.findOne(order.getGoodsId());
        if (goods == null) {
            CastException.cast(ShopCode.SHOP_GOODS_NO_EXIST);
        }
        //3.校验下单用户是否存在
        TradeUser user = userService.findOne(order.getUserId());
        if (user == null) {
            CastException.cast(ShopCode.SHOP_USER_NO_EXIST);
        }
        //4.校验商品单价是否合法
        if (order.getGoodsPrice().compareTo(goods.getGoodsPrice()) != 0) {
            CastException.cast(ShopCode.SHOP_GOODS_PRICE_INVALID);
        }
        //5.校验订单商品数量是否合法
        if (order.getGoodsNumber() >= goods.getGoodsNumber()) {
            CastException.cast(ShopCode.SHOP_GOODS_NUM_NOT_ENOUGH);
        }
        log.info("校验订单通过");
    }
}

2、在 shop-api 工程模块中，创建 IGoodsService.java 接口类。

package com.itheima.api;

import com.itheima.entity.Result;
import com.itheima.shop.pojo.TradeGoods;
import com.itheima.shop.pojo.TradeGoodsNumberLog;

public interface IGoodsService {
    /**
     * 根据ID查询商品对象
     * @param goodsId
     * @return
     */
    TradeGoods findOne(Long goodsId);


}

3、在 shop-api 工程模块中，创建 IUserService.java 接口类。

package com.itheima.api;

import com.itheima.entity.Result;
import com.itheima.shop.pojo.TradeUser;
import com.itheima.shop.pojo.TradeUserMoneyLog;

public interface IUserService {
    TradeUser findOne(Long userId);

    Result updateMoneyPaid(TradeUserMoneyLog userMoneyLog);
}

4、在 shop-user-service 工程模块中，创建 UserServiceImpl.java 实现类。

package com.itheima.shop.service.impl;

import com.alibaba.dubbo.config.annotation.Service;
import com.itheima.api.IUserService;
import com.itheima.constant.ShopCode;
import com.itheima.entity.Result;
import com.itheima.exception.CastException;
import com.itheima.shop.mapper.TradeUserMapper;
import com.itheima.shop.mapper.TradeUserMoneyLogMapper;
import com.itheima.shop.pojo.TradeUser;
import com.itheima.shop.pojo.TradeUserMoneyLog;
import com.itheima.shop.pojo.TradeUserMoneyLogExample;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import java.math.BigDecimal;
import java.util.Date;

@Component
@Service(interfaceClass = IUserService.class)
public class UserServiceImpl implements IUserService{

    @Autowired
    private TradeUserMapper userMapper;

    @Autowired
    private TradeUserMoneyLogMapper userMoneyLogMapper;

    @Override
    public TradeUser findOne(Long userId) {
        if(userId==null){
            CastException.cast(ShopCode.SHOP_REQUEST_PARAMETER_VALID);
        }
        return userMapper.selectByPrimaryKey(userId);
    }


}

5、在 shop-goods-service 工程模块中，创建 GoodsServiceImpl.java 实现类。

package com.itheima.shop.service.impl;

import com.alibaba.dubbo.config.annotation.Service;
import com.itheima.api.IGoodsService;
import com.itheima.constant.ShopCode;
import com.itheima.entity.Result;
import com.itheima.exception.CastException;
import com.itheima.shop.mapper.TradeGoodsMapper;
import com.itheima.shop.mapper.TradeGoodsNumberLogMapper;
import com.itheima.shop.pojo.TradeGoods;
import com.itheima.shop.pojo.TradeGoodsNumberLog;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import java.util.Date;

@Component
@Service(interfaceClass = IGoodsService.class)
public class GoodsServiceImpl implements IGoodsService {

    @Autowired
    private TradeGoodsMapper goodsMapper;

    @Autowired
    private TradeGoodsNumberLogMapper goodsNumberLogMapper;

    @Override
    public TradeGoods findOne(Long goodsId) {
        if (goodsId == null) {
            CastException.cast(ShopCode.SHOP_REQUEST_PARAMETER_VALID);
        }
        return goodsMapper.selectByPrimaryKey(goodsId);
    }

}

上一节关联链接请点击：
# RocketMQ 实战：模拟电商网站场景综合案例（五）

环境搭建：数据库表结构介绍–项目工程初始化 查看 请点击：
# RocketMQ 实战：模拟电商网站场景综合案例（三）

mybatis 逆向工程 生成 POJO 类 源文件 和 mapper 映射文件 查看 请点击：
RocketMQ 实战：模拟电商网站场景综合案例（四）