package com.example.luckdraw;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.serializer.SerializerFeature;
import lombok.Data;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.*;
/**
* 抽奖逻辑
*/
public class LuckDrawBox {
private static final Logger logger = LoggerFactory.getLogger(LuckDrawBox.class);
/**
* 抽奖
*
* @param users 抽奖用户
* @param prizes 待分配的奖品奖品
* @return 用户和奖品关联关系
*/
public Map<User, Prize> drawPrize(List<User> users, List<Prize> prizes) {
logger.info("LuckDrawBoxImpl drawPrize[抽奖] start users:{}, prizes:{}", users == null ? null : users.size(), prizes == null ? null : prizes.size());
Map<User, Prize> result = new HashMap<>(users == null ? 0 : users.size());
if (users == null || users.size() == 0 || prizes == null || prizes.size() == 0) {
logger.info("LuckDrawBoxImpl drawPrize[抽奖] 用户或奖品不存在");
return result;
}
// 奖品处理为奖品包装类
List<PrizeWrapper> prizeWrappers = getPrizeWrappers(prizes);
drawByPrizeProbability(users, result, prizeWrappers);
logger.info("LuckDrawBoxImpl drawPrize[抽奖] end result:{}", JSON.toJSONString(result, SerializerFeature.DisableCircularReferenceDetect));
return result;
}
/**
* 抽人
*
* @param users 抽奖用户
* @param prizes 待分配的奖品
* @return 用户和奖品关联关系
*/
public Map<User, Prize> drawPeople(List<User> users, List<Prize> prizes) {
logger.info("LuckDrawBoxImpl drawPeople[抽人] start users:{}, prizes:{}, poolSize:{}", users == null ? null : users.size(), prizes == null ? null : prizes.size());
Map<User, Prize> result = new HashMap<>(users == null ? 0 : users.size());
if (users == null || users.size() == 0 || prizes == null || prizes.size() == 0) {
logger.info("LuckDrawBoxImpl drawPeople[抽人] 用户或奖品不存在");
return result;
}
// 奖品处理为奖品包装类
List<PrizeWrapper> prizeWrappers = getPrizeWrappers(prizes);
// 抽奖用户放入到奖池
List<User> usersPool = new ArrayList<>(users);
// 抽人
Random random = new Random();
int seed;
for (PrizeWrapper item : prizeWrappers) {
for (int i = item.getStart(), length = item.getEnd() + 1; i < length; i++) {
if (usersPool.size() == 0) {
break;
}
seed = random.nextInt(usersPool.size());
// 中奖用户
logger.info("LuckDrawBoxImpl drawPeople[抽人] 用户 {} 抽中奖品 {}", usersPool.get(seed).getPin(), item.getPrize().getName());
result.put(usersPool.get(seed), item.getPrize());
// 移除中奖用户 暂不考虑多次中奖机会
usersPool.remove(usersPool.get(seed));
}
}
logger.info("LuckDrawBoxImpl drawPeople[抽人] end result:{}", JSON.toJSONString(result, SerializerFeature.DisableCircularReferenceDetect));
return result;
}
/**
* 处理为奖品包装类
*
* @param prizes 奖品
* @return 奖品包装类
*/
private List<PrizeWrapper> getPrizeWrappers(List<Prize> prizes) {
List<PrizeWrapper> prizeWrappers = new ArrayList<>(prizes.size());
int prizePoint = 0;
for (Prize item : prizes) {
// 剩余奖品数量
int remainder = item.getQuantity() - item.getWinningQuantity();
logger.info("LuckDrawBoxImpl drawPrize[抽奖] {} 剩余奖品数量 {}", item.getName(), remainder);
if (remainder == 0) {
continue;
}
PrizeWrapper prizeWrapper = new PrizeWrapper();
prizeWrapper.setStart(prizePoint);
// 下一个奖品的开始点
prizePoint += remainder;
prizeWrapper.setEnd(prizePoint - 1);
prizeWrapper.setPrize(item);
prizeWrappers.add(prizeWrapper);
}
return prizeWrappers;
}
/**
* 基于奖品概率抽奖，每个奖品独立抽奖机会
*
* @param users 用户
* @param result 抽奖结果
* @param prizeWrappers 奖品包装类
*/
private void drawByPrizeProbability(List<User> users, Map<User, Prize> result, List<PrizeWrapper> prizeWrappers) {
// 默认奖池基数
int poolSize = 1000000;
Random random = new Random();
for (User user : users) {
Prize winnerPrize = null;
for (PrizeWrapper prizeWrapper : prizeWrappers) {
int seed = random.nextInt(poolSize);
if (prizeWrapper.quantity > 0 && seed < prizeWrapper.getPrize().getProbability()) {
winnerPrize = prizeWrapper.getPrize();
prizeWrapper.quantity--;
break;
}
}
if (winnerPrize != null) {
logger.info("LuckDrawBoxImpl drawPrize[抽奖] 用户 {} 抽中奖品 {}", user.getPin(), winnerPrize.getName());
} else {
logger.info("LuckDrawBoxImpl drawPrize[抽奖] 用户 {} 没有抽中奖品", user.getPin());
}
result.put(user, winnerPrize);
}
}
/**
* 基于基数抽奖，奖品数量代表不同的机会
*
* @param users 用户
* @param poolSize 奖池基数
* @param result 抽奖结果
* @param prizeWrappers 奖品包装类
*/
private void drawByBaseNumber(List<User> users, int poolSize, Map<User, Prize> result, List<PrizeWrapper> prizeWrappers) {
// 默认奖池基数
if (poolSize == 0) {
poolSize = 10000;
}
// 开始抽奖
Random random = new Random();
for (User user : users) {
int seed = random.nextInt(poolSize);
Prize winnerPrize = null;
for (PrizeWrapper prizeWrapper : prizeWrappers) {
if (seed >= prizeWrapper.getStart() && seed <= prizeWrapper.getEnd()) {
winnerPrize = prizeWrapper.getPrize();
break;
}
}
if (winnerPrize != null) {
logger.info("LuckDrawBoxImpl drawPrize[抽奖] 用户 {} 抽中奖品 {}", user.getPin(), winnerPrize.getName());
} else {
logger.info("LuckDrawBoxImpl drawPrize[抽奖] 用户 {} 没有抽中奖品", user.getPin());
}
result.put(user, winnerPrize);
}
}
/**
* 奖品包装类
*/
@Data
private class PrizeWrapper {
private int start;
private int end;
private int quantity;
private Prize prize;
}
/**
* 用户
*/
@Data
private class User {
private String pin;
private String name;
}
/**
* 奖品
*/
@Data
private class Prize {
private String name;
private int quantity;
private int winningQuantity;
private int probability;
}
}
抽奖ER图.drawio
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