java抽獎系統的設計「java抽獎程序代碼」

獎品類：

抽獎邏輯：

測試類：

測試結果：

商品類：

package org.plusgroup.modules.app.controller.vo;

import io.swagger.annotations.ApiModelProperty;
import lombok.Data;

import java.util.ArrayList;
import java.util.List;

/**
 * @author Administrator
 * @desc 獎品VO
 * @date 2021/7/9 14:30
 */
@Data
public class PrizeVo {
    @ApiModelProperty("獎品ID")
    private Integer id;
    @ApiModelProperty("獎品名稱")
    private String name;
    @ApiModelProperty("獎品編號")
    private String code;
    @ApiModelProperty("中獎概率")
    private Double rate;

    public PrizeVo(Integer id, String name, String code, Double rate) {
        this.id = id;
        this.name = name;
        this.code = code;
        this.rate = rate;
    }
    public PrizeVo() {
    }

    /**
     * 初始化獎品
     * @return List
     */
    public static List<PrizeVo> init(){
        List<PrizeVo> list = new ArrayList<>();
        list.add(new PrizeVo(10, "文檔列印券", "P1", 0.2d));
        list.add(new PrizeVo(20, "照片列印券", "P2", 0.5d));
        list.add(new PrizeVo(30, "5元代金券", "P3", 0.1d));
        list.add(new PrizeVo(40, "謝謝參與", "P4", 0.2d));
        return list;
    }
}

測試類：

package org.plusgroup.modules.admin.service;

import org.plusgroup.modules.app.controller.vo.PrizeVo;
import org.springframework.util.CollectionUtils;

import java.util.*;

/**
 * @author Administrator
 * @desc
 * @date 2021/7/9 14:43
 */
public class IntegralLogTest {

    public static void main(String [] args){
        //獎品中獎概率集合
        List<Double> rates = new ArrayList<>();
        //將每個獎品的概率放入概率集合
        List<PrizeVo> list = PrizeVo.init();
        for(PrizeVo prizeVo : list){
            rates.add(prizeVo.getRate());
        }
        System.out.println("本次中獎商品下標:" +luckDraw(rates));

        // 統計每種商品中獎次數
        Map<Integer, Integer> countMap = new HashMap<>();
        double num = 10000; //測試次數
        for (int i = 0; i < num; i++) {
            int key = luckDraw(rates);
            Integer value = countMap.get(key);
            countMap.put(key, value == null ? 1 : value + 1);
        }
        for (Map.Entry<Integer, Integer> entry : countMap.entrySet()) {
            System.out.println(list.get(entry.getKey()) + ", 命中次數=" + entry.getValue() + ", 實際概率=" + entry.getValue() / num);
        }
    }


    /**
     * 抽獎邏輯
     * @param rates 概率集合
     * @return int
     */
    public static int luckDraw(List<Double> rates) {
        if (CollectionUtils.isEmpty(rates)) {
            return -1;
        }
        //計算總概率，概率集合累加
        double totalRate = 0d;
        for (double rate : rates) {
            totalRate += rate;
        }
        // 每個獎品在總概率基礎下的概率
        List<Double> sortRates = new ArrayList<>();
        double everyRate = 0d;
        for (double rate : rates) {
            everyRate += rate;
            sortRates.add(everyRate / totalRate);
        }
        // 根據區塊值來獲取抽取到的物品索引
        double nextDouble = Math.random();
        sortRates.add(nextDouble);
        Collections.sort(sortRates);

        return sortRates.indexOf(nextDouble);
    }
}