按比例随机发奖

public class HwService {

	public static Map<Integer, HwAward> awardMap = new HashMap<Integer, HwAward>();

	public static Object lock = new Object(); //锁

	public static int[] awardIndexs = null; //奖品索引

        /**
	 * 重新生成奖品索引数组
	 * 
	 * @return
	 */
	private int[] regenerateAwardIndexs() {
		Set<Integer> keys = HwService.awardMap.keySet();
		int seedCount = keys.size();// 当前因子个数
		int[] awardIndexs = new int[seedCount];
		int count = 0;
		for (int j : keys) {
			awardIndexs[count] = j;
			count++;
		}
		return awardIndexs;
	}

}



public static void main(String[] args) {
	
	 Runnable r = new Runnable() {
	 public void run() {
	 HwService service = new HwService();
	 Random ran = new Random();
	
	 int i = 0;
	 while (i < 150000) {
	
	 int seedCount = HwService.awardMap.size();// 当前种子个数
	 if (seedCount == 0) {
	 System.out.println("发光了！！！！！");
	 break;
	 }
	 HwAward award = HwService.awardMap.get(awardIndexs[ran
	 .nextInt(seedCount)]);// 根据当前因子个数随机
	 synchronized (lock) {
	 int nowLeft = award.getLeftAmount() - 1; // 当前剩余个数-1
	 award.setLeftAmount(nowLeft); // 更新剩余个数
	 if (nowLeft == 0) {
	 HwService.awardMap.remove(award.getAwardId()); // 从奖品列表移除
	 awardIndexs = service.regenerateAwardIndexs(); // 重新生成因子
	 System.out.println(award.getAwardBreif()
	 + " 发光了！！！ ID " + award.getAwardId());
	 System.out.println("当前奖品列表个数  "
	 + HwService.awardMap.size());
	 }
	 }
	 i++;
	 }
	
	 System.out.println("当前还有 " + i + " 人未领奖");
	 }
	 };
	 Thread t1 = new Thread(r);
	 Thread t2 = new Thread(r);
	 Thread t3 = new Thread(r);
	 Thread t4 = new Thread(r);
	 Thread t5 = new Thread(r);
	
	 t1.start();
	 t2.start();
	 t3.start();
	 t4.start();
	 t5.start();
}

备忘,缺点是要先确定按比例算出的总数，然后减到0的就不会出现在随机队列里面了