RandomUtil.java

package cn.chnmuseum.party.common.util;

import java.util.Random;

public class RandomUtil {

    public static String[] arr = {
            "0", "1", "2", "3", "4", "5", "6", "7", "8", "9",
            "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z",
            "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"
    };

    /**
     * 创建指定数量的随机字符串
     *
     * @param length
     * @return
     */
    public static String createRandom(int length) {
        String retStr = null;
        String strTable = "1234567890";
        int len = strTable.length();
        boolean bDone = true;
        do {
            retStr = "";
            int count = 0;
            for (int i = 0; i < length; i++) {
                double dblR = Math.random() * len;
                int intR = (int) Math.floor(dblR);
                char c = strTable.charAt(intR);
                if (('0' <= c) && (c <= '9')) {
                    count++;
                }
                retStr += strTable.charAt(intR);
            }
            if (count >= 2) {
                bDone = false;
            }
        } while (bDone);
        return retStr;
    }

    public static String createLetterRandom(int length) {
        StringBuilder retStr;
        String strTable = "1234567890abcdef";
        int len = strTable.length();
        boolean bDone = true;
        do {
            retStr = new StringBuilder();
            int count = 0;
            for (int i = 0; i < length; i++) {
                double dblR = Math.random() * len;
                int intR = (int) Math.floor(dblR);
                char c = strTable.charAt(intR);
                if (('0' <= c) && (c <= '9')) {
                    count++;
                }
                retStr.append(strTable.charAt(intR));
            }
            if (count >= 2) {
                bDone = false;
            }
        } while (bDone);
        return retStr.toString();
    }

    public static String createCipher(int length) {
        StringBuilder retStr;
        String strTable = "1234567890abcdef";
        int len = strTable.length();
        boolean bDone = true;
        do {
            retStr = new StringBuilder();
            int count = 0;
            for (int i = 0; i < length; i++) {
                double dblR = Math.random() * len;
                int intR = (int) Math.floor(dblR);
                char c = strTable.charAt(intR);
                if (('0' <= c) && (c <= '9')) {
                    count++;
                }
                retStr.append(strTable.charAt(intR));
            }
            if (count >= 2) {
                bDone = false;
            }
        } while (bDone);
        return retStr.toString();
    }

    public static String getRandom(Integer len) {
        String nums = "";
        for (int i = 0; i < len; i++) {
            Random r = new Random();
            int index = r.nextInt(arr.length - 1);
            String str = arr[index];
            nums = nums + str;
        }
        return nums;
    }

}