通过redis实现的一个抢红包流程，仅做模拟【上】

@MappedSuperclass

@Data

@NoArgsConstructor

@AllArgsConstructor

public class BaseEntity {//公共基础实体字段

    @Id //标识主键 公用主键

    @GeneratedValue //递增序列

    private Long id;

    @Column(updatable = false) //不允许修改

    @CreationTimestamp //创建时自动赋值

    private Date createTime;

    @UpdateTimestamp //修改时自动修改

    private Date updateTime;

}

@Entity //标识这是个jpa数据库实体类

@Table

@Data   //lombok getter setter tostring

@ToString(callSuper = true) //覆盖tostring 包含父类的字段

@Slf4j  //SLF4J log

@Builder //biulder模式

@NoArgsConstructor //无参构造函数

@AllArgsConstructor  //全参构造函数

@JsonIgnoreProperties({"hibernateLazyInitializer", "handler"})

public class RedPacketInfo extends BaseEntity implements Serializable {//红包信息表

    private String red_packet_id;//红包ID

    private int total_amount;//总金额

    private int total_packet;//总红包数

    private int remaining_amount;//剩余金额

    private  int remaining_packet;//剩余红包数

    private String user_id;//发红包用户ID

}

@Entity //标识这是个jpa数据库实体类

@Table

@Data   //lombok getter setter tostring

@ToString(callSuper = true) //覆盖tostring 包含父类的字段

@Slf4j  //SLF4J log

@Builder //biulder模式

@NoArgsConstructor //无参构造函数

@AllArgsConstructor  //全参构造函数

@JsonIgnoreProperties({"hibernateLazyInitializer", "handler"})

public class RedPacketRecord extends BaseEntity implements Serializable {//抢红包记录表

    private int amount;

    private String red_packet_id;

    private String user_id;

}

 /**

     * 发红包

     * @param userId

     * @param total_amount 单位为分，不允许有小数点

     * @param tal_packet

     * @return

     */

    public RedPacketInfo handOut(String userId,int total_amount,int tal_packet){

        RedPacketInfo redPacketInfo = new RedPacketInfo();

        redPacketInfo.setRed_packet_id(genRedPacketId(userId));

        redPacketInfo.setTotal_amount(total_amount);

        redPacketInfo.setTotal_packet(tal_packet);

        redPacketInfo.setRemaining_amount(total_amount);

        redPacketInfo.setRemaining_packet(tal_packet);

        redPacketInfo.setUser_id(userId);

        redPacketInfoRepository.save(redPacketInfo);

        redisUtil.set(redPacketInfo.getRed_packet_id()+TAL_PACKET, tal_packet+"");

        redisUtil.set(redPacketInfo.getRed_packet_id()+TOTAL_AMOUNT, total_amount+"");

        return redPacketInfo;

    }

/**

     * 组织红包ID

     * @return

     */

    private String genRedPacketId(String userId){

        String redpacketId = userId+"_"+new Date().getTime()+"_"+redisUtil.incrBy("redpacketid",1);

        return redpacketId;

    }

/**

     * 抢红包

     * @param userId

     * @param redPacketId

     * @return

     */

    public GrabResult grab(String userId, String redPacketId){

        Date begin = new Date();

        String msg = "红包已经被抢完！";

        boolean resultFlag = false;

        double amountdb = 0.00;

        try{

            //抢红包的过程必须保证原子性，此处加分布式锁

            if(redisUtil.getLock(redPacketId+"_lock")) {

                RedPacketRecord redPacketRecord = new RedPacketRecord().builder().red_packet_id(redPacketId)

                        .user_id(userId).build();

                //如果没有红包了，则返回

                if (Integer.parseInt(redisUtil.get(redPacketId + TAL_PACKET)) <= 0) {

                }else {

                    //抢红包过程

                    //获取剩余金额 单位分

                    int remaining_amount = Integer.parseInt(redisUtil.get(redPacketId + TOTAL_AMOUNT));

                    //获取剩余红包数

                    int remaining_packet = Integer.parseInt(redisUtil.get(redPacketId + TAL_PACKET));

                    //计算本次抢红包金额

                    //计算公式：remaining_amount/remaining_packet*2

                    //如果只剩下一个红包，则余额全由这次的人获得

                    int amount = remaining_amount;

                    if (remaining_packet != 1) {

                        int maxAmount = remaining_amount / remaining_packet * 2;

                        amount = Integer.parseInt(randomValuePropertySource.getProperty("random.int[0," + maxAmount + "]").toString());

                    }

                    //与redis进行incrBy应该原子，并且2次与redis交互还有一定性能消耗，通过lua脚本实现更为妥当

                    redisUtil.incrBy(redPacketId + TAL_PACKET, -1);

                    redisUtil.incrByFloat(redPacketId + TOTAL_AMOUNT, -amount);

                    //准备返回结果

                    redPacketRecord.setAmount(amount);

                    amountdb = amount / 100.00;

                    msg = "恭喜你抢到红包，红包金额" + amountdb + "元！";

                    resultFlag = true;

                    //异步记账

                    try {

                        redPacketCallBackService.callback(userId, redPacketId,

                                Integer.parseInt(redisUtil.get(redPacketId + TAL_PACKET)),

                                Integer.parseInt(redisUtil.get(redPacketId + TOTAL_AMOUNT)),

                                amount);

                    } catch (Exception e) {

                        log.error(e.getMessage(), e);

                    }

                }

            }

        }finally {

            //解锁redis分布式锁

            redisUtil.unLock(redPacketId+"_lock");

        }

        Date end = new Date();

        System.out.println(msg+",剩余红包："+redisUtil.get(redPacketId + TAL_PACKET)+"个,本次抢红包消耗："+(end.getTime()-begin.getTime())+"毫秒");

        return new GrabResult().builder().msg(msg).resultFlag(resultFlag).amount(amountdb).red_packet_id(redPacketId).user_id(userId).build();

    }