java随机红包

 /**  
 *@Description:     
 */ 
package com.lulei.weixin.util;  
 
import java.util.ArrayList;
import java.util.List;
 
import com.lulei.util.JsonUtil;
  
public class RedPacketUtil {
	//最小红包额度
	private static final int MINMONEY = 1;
	//最大红包额度
	private static final int MAXMONEY = 200 * 100;
	//每个红包最大是平均值的倍数
	private static final double TIMES = 2.1;
	
	/**
	 * @param money
	 * @param count
	 * @return
	 * @Author:lulei  
	 * @Description: 拆分红包
	 */
	public List splitRedPackets(int money, int count) {
		if (!isRight(money, count)) {
			return null;
		}
		List list = new ArrayList();
		//红包最大金额为平均金额的TIMES倍
		int max = (int) (money * TIMES / count);
		max = max > MAXMONEY ? MAXMONEY : max;
		for (int i = 0; i < count; i++) {
			int one = random(money, MINMONEY, max, count - i);
			list.add(one);
			money -= one;
		}
		return list;
	}
	
	/**
	 * @param money
	 * @param minS
	 * @param maxS
	 * @param count
	 * @return
	 * @Author:lulei  
	 * @Description: 随机红包额度
	 */
	private int random(int money, int minS, int maxS, int count) {
		//红包数量为1，直接返回金额
		if (count == 1) {
			return money;
		}
		//如果最大金额和最小金额相等，直接返回金额
		if (minS == maxS) {
			return minS;
		}
		int max = maxS > money ? money : maxS;
		//随机产生一个红包
		int one = ((int)Math.rint(Math.random() * (max - minS) + minS))  % max + 1;
		int money1 = money - one;
		//判断该种分配方案是否正确
		if (isRight(money1, count -1)) {
			return one;
		} else {
			double avg = money1 / (count - 1);
			if (avg < MINMONEY) {
				//递归调用，修改红包最大金额
				return random(money, minS, one, count);
			}else if (avg > MAXMONEY) {
				//递归调用，修改红包最小金额
				return random(money, one, maxS, count);
			}
		}
		return one;
	}
	
	/**
	 * @param money
	 * @param count
	 * @return
	 * @Author:lulei  
	 * @Description: 此种红包是否合法
	 */
	private boolean isRight(int money, int count) {
		double avg = money / count;
		if (avg < MINMONEY) {
			return false;
		}
		if (avg > MAXMONEY) {
			return false;
		}
		return true;
	}
 
	public static void main(String[] args) {
		// TODO Auto-generated method stub  
		RedPacketUtil util = new RedPacketUtil();
		System.out.println(JsonUtil.parseJson(util.splitRedPackets(20000, 100)));
	}
}