//创建一个分发器 RandomDispatcher randomDispatcher = new RandomDispatcher(); //设置每种事件的概率，注意，概率之和不一定是100哦 randomDispatcher.put(20, 1); randomDispatcher.put(1, 2); randomDispatcher.put(29, 3); randomDispatcher.put(50, 4); //随机 int retIndex = randomDispatcher.random(); //根据随机结果去执行不同的方法 switch (retIndex) { case 1:  System.out.println("do method A");  break; case 2:  System.out.println("do method B");  break; case 3:  System.out.println("do method C");  break; case 4:  System.out.println("do method D");  break; default:  break; }