Base62，,package com.

Base62，,package com.

package com.sohu.idcenter;public class Base62 {    private static final String baseDigits = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";    private static final int BASE = baseDigits.length();    private static final char[] digitsChar = baseDigits.toCharArray();    private static final int FAST_SIZE = 'z';    private static final int[] digitsIndex = new int[FAST_SIZE + 1];    static {        for (int i = 0; i < FAST_SIZE; i++) {            digitsIndex[i] = -1;        }        //        for (int i = 0; i < BASE; i++) {            digitsIndex[digitsChar[i]] = i;        }    }    public static long decode(String s) {        long result = 0L;        long multiplier = 1;        for (int pos = s.length() - 1; pos >= 0; pos--) {            int index = getIndex(s, pos);            result += index * multiplier;            multiplier *= BASE;        }        return result;    }    public static String encode(long number) {        if (number < 0) throw new IllegalArgumentException("Number(Base62) must be positive: " + number);        if (number == 0) return "0";        StringBuilder buf = new StringBuilder();        while (number != 0) {            buf.append(digitsChar[(int) (number % BASE)]);            number /= BASE;        }        return buf.reverse().toString();    }    private static int getIndex(String s, int pos) {        char c = s.charAt(pos);        if (c > FAST_SIZE) {            throw new IllegalArgumentException("Unknow character for Base62: " + s);        }        int index = digitsIndex[c];        if (index == -1) {            throw new IllegalArgumentException("Unknow character for Base62: " + s);        }        return index;    }}//该片段来自于http://byrx.net