java抽奖算法

import java.util.ArrayList;import java.util.List;import java.util.Random;import org.springframework.stereotype.Service;import net.sf.json.JSONArray;import net.sf.json.JSONObject;/** * 转盘抽奖逻辑 *  * @author zwm * @date 2017-05-11 */@Servicepublic class LotteryTool {public static void main(String[] args) {List<Award> awards = new ArrayList<>();awards.add(new Award("a1", 0.1f, 10));awards.add(new Award("a2", 0.2f, 0));awards.add(new Award("a3", 0.3f, 10));awards.add(new Award("a4", 0.05f, 10));awards.add(new Award("a5", 0.2f, 100));for (int i = 0; i < 10; i++) {System.out.println("恭喜您，抽到了：" + lottery(awards).id);}}public static Award lottery(List<Award> awards) {// 总的概率区间float totalPro = 0f;// 存储每个奖品新的概率区间List<Float> proSection = new ArrayList<Float>();proSection.add(0f);// 遍历每个奖品，设置概率区间，总的概率区间为每个概率区间的总和for (Award award : awards) {// 每个概率区间为奖品概率乘以1000（把三位小数转换为整）再乘以剩余奖品数量totalPro += award.probability * 1000 * award.count;proSection.add(totalPro);}// 获取总的概率区间中的随机数Random random = new Random();float randomPro = (float) random.nextInt((int) totalPro);// 判断取到的随机数在哪个奖品的概率区间中for (int i = 0, size = proSection.size(); i < size; i++) {if (randomPro >= proSection.get(i) && randomPro < proSection.get(i + 1)) {return awards.get(i);}}return null;}static class Award {/** 编号 */public String id;/** 概率（0.1代表10%，最多3位小数，即千分之一级） */public float probability;/** 数量（该类奖品剩余数量） */public int count;public Award(String id, float probability, int count) {super();this.id = id;this.probability = probability;this.count = count;}public Award() {}}}