随机生成无序码

根据id随机生成无序的码

该代码来自网上，原网址记不清了。

实践

package com.hoodong.engine.util;

import java.util.Random;

/**
 * ShareCodeUtils
 *
 * @Title: ShareCodeUtils.java
 * @Copyright: Copyright (c) 2005
 * @Description:
 * @Created on 2018-12-5 13:18
 * @Author 90
 */
public class ShareCodeUtils {
    /**
     * 自定义进制(0,1没有加入,容易与o,l混淆)，数组顺序可进行调整增加反推难度，A用来补位因此此数组不包含A，共31个字符。
     */
    private static final char[] BASE = new char[]{'H', 'V', 'E', '8', 'S', '2', 'D', 'Z', 'X', '9', 'C', '7', 'P',
            '5', 'I', 'K', '3', 'M', 'J', 'U', 'F', 'R', '4', 'W', 'Y', 'L', 'T', 'N', '6', 'B', 'G', 'Q'};
    /**
     * A补位字符，不能与自定义重复
     */
    private static final char SUFFIX_CHAR = 'A';
    /**
     * 进制长度
     */
    private static final int BIN_LEN = BASE.length;
    /**
     * 生成邀请码最小长度
     */
    private static final int CODE_LEN = 6;
    /**
     * ID转换为邀请码
     *
     * @param id
     * @return
     */
    public static String idToCode(Long id) {
        char[] buf = new char[BIN_LEN];
        int charPos = BIN_LEN;
        // 当id除以数组长度结果大于0，则进行取模操作，并以取模的值作为数组的坐标获得对应的字符
        while (id / BIN_LEN > 0) {
            int index = (int) (id % BIN_LEN);
            buf[--charPos] = BASE[index];
            id /= BIN_LEN;
        }
        buf[--charPos] = BASE[(int) (id % BIN_LEN)];
        // 将字符数组转化为字符串
        String result = new String(buf, charPos, BIN_LEN - charPos);
        // 长度不足指定长度则随机补全
        int len = result.length();
        if (len < CODE_LEN) {
            StringBuilder sb = new StringBuilder();
            sb.append(SUFFIX_CHAR);
            Random random = new Random();
            // 去除SUFFIX_CHAR本身占位之后需要补齐的位数
            for (int i = 0; i < CODE_LEN - len - 1; i++) {
                sb.append(BASE[random.nextInt(BIN_LEN)]);
            }
            result += sb.toString();
        }
        return result;
    }
    /**
     * 邀请码解析出ID<br/>
     * 基本操作思路恰好与idToCode反向操作。
     *
     * @param code
     * @return
     */
    public static Long codeToId(String code) {
        char[] charArray = code.toCharArray();
        long result = 0L;
        for (int i = 0; i < charArray.length; i++) {
            int index = 0;
            for (int j = 0; j < BIN_LEN; j++) {
                if (charArray[i] == BASE[j]) {
                    index = j;
                    break;
                }
            }
            if (charArray[i] == SUFFIX_CHAR) {
                break;
            }
            if (i > 0) {
                result = result * BIN_LEN + index;
            } else {
                result = index;
            }
        }
        return result;
    }

    /**
     *@Author: 90
     *@Description 随机n个不重复的数字
     *@Param  * @param null
     *@Date 12:57 2018-12-5
     */
    public static int[] randomCommon(int min, int max, int n){
        if (n > (max - min + 1) || max < min) {
            return null;
        }
        int[] result = new int[n];
        int count = 0;
        while(count < n) {
            int num = (int) (Math.random() * (max - min)) + min;
            boolean flag = true;
            for (int j = 0; j < n; j++) {
                if(num == result[j]){
                    flag = false;
                    break;
                }
            }
            if(flag){
                result[count] = num;
                count++;
            }
        }
        return result;
    }
    public static void main(String[] args) {
        String code = idToCode(1111L);
        System.out.println(code);
        System.out.println(codeToId(code));
    }




}