转盘抽奖算法（java）

public class LuckDraw {

    public int getPrizeIndex(List
 
   prizes) throws Exception {
        int random = -1;
        //计算总权重
        double sumWeight = 0;
        for (GoodsEntity p : prizes) {
            sumWeight += p.getPrizeWeight();
        }

        //产生随机数
        double randomNumber;
        randomNumber = Math.random();
        //根据随机数在所有奖品分布的区域并确定所抽奖品
        double d1 = 0;
        double d2 = 0;
        for (int i = 0; i < prizes.size(); i++) {
            d2 += Double.parseDouble(String.valueOf(prizes.get(i).getPrizeWeight())) / sumWeight;
            if (i == 0) {
                d1 = 0;
            } else {
                d1 += Double.parseDouble(String.valueOf(prizes.get(i - 1).getPrizeWeight())) / sumWeight;
            }
            if (randomNumber > d1 && randomNumber <= d2) {
                random = i;
                break;
            }
        }
        return random;
    }

}
 

@Entity
@Table(name = "goods")
public class GoodsEntity {
    private Long goodsId;
    private String goodsName;
    private Byte dataStatus;
    private Timestamp createTime;
    private Byte ranking;
    private Integer prizeWeight;
    private BigDecimal price;
    private Integer version;

    @Id
    @Column(name = "goods_id", nullable = false)
    public Long getGoodsId() {
        return goodsId;
    }

    public void setGoodsId(Long goodsId) {
        this.goodsId = goodsId;
    }

    @Basic
    @Column(name = "goods_name", nullable = true, length = 50)
    public String getGoodsName() {
        return goodsName;
    }

    public void setGoodsName(String goodsName) {
        this.goodsName = goodsName;
    }

    @Basic
    @Column(name = "data_status", nullable = true)
    public Byte getDataStatus() {
        return dataStatus;
    }

    public void setDataStatus(Byte dataStatus) {
        this.dataStatus = dataStatus;
    }

    @Basic
    @Column(name = "create_time", nullable = false)
    public Timestamp getCreateTime() {
        return createTime;
    }

    public void setCreateTime(Timestamp createTime) {
        this.createTime = createTime;
    }

    @Basic
    @Column(name = "ranking", nullable = true)
    public Byte getRanking() {
        return ranking;
    }

    public void setRanking(Byte ranking) {
        this.ranking = ranking;
    }

    @Basic
    @Column(name = "prize_weight", nullable = true)
    public Integer getPrizeWeight() {
        return prizeWeight;
    }

    public void setPrizeWeight(Integer prizeWeight) {
        this.prizeWeight = prizeWeight;
    }

    @Basic
    @Column(name = "version", nullable = true)
    public Integer getVersion() {
        return version;
    }

    public void setVersion(Integer version) {
        this.version = version;
    }

    @Basic
    @Column(name = "price", nullable = true)
    public BigDecimal getPrice() {
        return price;
    }

    public void setPrice(BigDecimal price) {
        this.price = price;
    }
}

public Map
 
   luckDraw() {
        Map
  
    result = new HashMap
   
    (); try { List
    
      goodsEntityList = goodsService.getGoods();//参与抽奖的商品列表 int selected = luckDraw.getPrizeIndex(goodsEntityList); ResponseGoods responseGoods = new ResponseGoods(); responseGoods.setGoodsName(goodsEntityList.get(selected).getGoodsName()); responseGoods.setPrice(goodsEntityList.get(selected).getPrice()); result.put("result", responseGoods); } catch (Exception e) { e.printStackTrace(); } return result; }