随机数环设想

import java.util.concurrent.ThreadLocalRandom;
/** * Created by Kowalski on 2017/1/22. *  */public class RandomIdWorker {
    /**位运算数组*/    private static final int[] arr_32 = {            0x80000000,0x40000000,0x20000000,0x10000000,            0x08000000,0x04000000,0x02000000,0x01000000,            0x00800000,0x00400000,0x00200000,0x00100000,            0x00080000,0x00040000,0x00020000,0x00010000,            0x00008000,0x00004000,0x00002000,0x00001000,            0x00000800,0x00000400,0x00000200,0x00000100,            0x00000080,0x00000040,0x00000020,0x00000010,            0x00000008,0x00000004,0x00000002,0x00000001,    };    /**随机数最大值*/    private static int bitNum;    /**随机数长度*/    private static int circleLenNum;    /**当前圈数*/    private static int circleNum;    /**圈最大值*/    private static int maxCircleNum;    /**摧毁圈长度*/    private static int destoryLen;    /**环数组*/    private static int[] arr;    /**随机数*/    private static ThreadLocalRandom random = ThreadLocalRandom.current();
    public static void init(int bitNum, int maxCircleNum, int destoryLen) {
        if(destoryLen > bitNum) {            throw new IllegalArgumentException("destoryLen can not big than bitNum");        } else {            /**初始化数组*/            arr = new int[bitNum / 32 + 1];            /**初始化参数*/            RandomIdWorker.bitNum = bitNum;            RandomIdWorker.maxCircleNum = maxCircleNum;            RandomIdWorker.destoryLen = destoryLen;
            for(circleLenNum = 10; bitNum / 10 != 0; bitNum /= 10) {                circleLenNum *= 10;            }
        }    }
    public static void main(String... args){
        init(9999, 9999, 100);
        int res = 0;        long time = System.currentTimeMillis();        for (int i = 0; i < 10000000; i++) {            res = generate();        }        System.out.println(System.currentTimeMillis() - time);        System.out.println(res);        System.out.println("圈数:" + circleNum);    }
    public static synchronized int generate(){
        /**取随机数*/        int ran = random.nextInt(bitNum);        /**核心代码*/        int i;        for(i = 0; i < destoryLen; ++i) {            if ((arr[ran / 32] & arr_32[ran % 32]) == 0) {
                arr[ran / 32] |= arr_32[ran % 32];
                return circleLenNum*circleNum + ran;            }            /**数已存在就取下一个*/            ran = (ran + 1) % bitNum;        }        /**到达最大圈数 从头开始*/        if(circleNum == maxCircleNum){            circleNum = 0;
        }else {            ++circleNum;        }        /**清空数组*/        for (i = 0; i < bitNum / 32 + 1; ++i) {            arr[i] = 0;        }        /**将新数组中ran位设成1*/        arr[ran / 32] |= arr_32[ran % 32];
        return circleLenNum*circleNum + ran;    }
}