Java使用Base58压缩UUID

大数据时代，自增长的主键形式已经完全不能满足现有的业务，很早便使用UUID主键形式，但是弊端是太长，

EG:   7174f86a-b569-4b85-b303-0135d839c5a9

高达36位之巨-_-#，即便处理掉了横杠也有32位，这也不是一个小数目。

看了比特币采用Base58的主键形式，感觉非常良好，相关地址：https://en.bitcoin.it/wiki/Base58Check_encoding

它的算法源码文件为：https://code.google.com/p/bitcoinj/source/browse/core/src/main/java/com/google/bitcoin/core/Base58.java

项目jar 下载地址为https://code.google.com/p/bitcoinj/downloads/list  但是一直未能成功，难道是天朝的原因么:-D

那么就自己动手抄抄吧 ：）
Base58.java

package org.ne.framework.data.util;

public class Base58 {

	private static final char[] ALPHABET = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"
			.toCharArray();
	private static final int BASE_58 = ALPHABET.length;
	private static final int BASE_256 = 256;

	private static final int[] INDEXES = new int[128];
	static {
		for (int i = 0; i < INDEXES.length; i++) {
			INDEXES[i] = -1;
		}
		for (int i = 0; i < ALPHABET.length; i++) {
			INDEXES[ALPHABET[i]] = i;
		}
	}

	public static String encode(byte[] input) {
		if (input.length == 0) {
			// paying with the same coin
			return "";
		}

		//
		// Make a copy of the input since we are going to modify it.
		//
		input = copyOfRange(input, 0, input.length);

		//
		// Count leading zeroes
		//
		int zeroCount = 0;
		while (zeroCount < input.length && input[zeroCount] == 0) {
			++zeroCount;
		}

		//
		// The actual encoding
		//
		byte[] temp = new byte[input.length * 2];
		int j = temp.length;

		int startAt = zeroCount;
		while (startAt < input.length) {
			byte mod = divmod58(input, startAt);
			if (input[startAt] == 0) {
				++startAt;
			}

			temp[--j] = (byte) ALPHABET[mod];
		}

		//
		// Strip extra '1' if any
		//
		while (j < temp.length && temp[j] == ALPHABET[0]) {
			++j;
		}

		//
		// Add as many leading '1' as there were leading zeros.
		//
		while (--zeroCount >= 0) {
			temp[--j] = (byte) ALPHABET[0];
		}

		byte[] output = copyOfRange(temp, j, temp.length);
		return new String(output);
	}

	public static byte[] decode(String input) {
		if (input.length() == 0) {
			// paying with the same coin
			return new byte[0];
		}

		byte[] input58 = new byte[input.length()];
		//
		// Transform the String to a base58 byte sequence
		//
		for (int i = 0; i < input.length(); ++i) {
			char c = input.charAt(i);

			int digit58 = -1;
			if (c >= 0 && c < 128) {
				digit58 = INDEXES[c];
			}
			if (digit58 < 0) {
				throw new RuntimeException("Not a Base58 input: " + input);
			}

			input58[i] = (byte) digit58;
		}

		//
		// Count leading zeroes
		//
		int zeroCount = 0;
		while (zeroCount < input58.length && input58[zeroCount] == 0) {
			++zeroCount;
		}

		//
		// The encoding
		//
		byte[] temp = new byte[input.length()];
		int j = temp.length;

		int startAt = zeroCount;
		while (startAt < input58.length) {
			byte mod = divmod256(input58, startAt);
			if (input58[startAt] == 0) {
				++startAt;
			}

			temp[--j] = mod;
		}

		//
		// Do no add extra leading zeroes, move j to first non null byte.
		//
		while (j < temp.length && temp[j] == 0) {
			++j;
		}

		return copyOfRange(temp, j - zeroCount, temp.length);
	}

	private static byte divmod58(byte[] number, int startAt) {
		int remainder = 0;
		for (int i = startAt; i < number.length; i++) {
			int digit256 = (int) number[i] & 0xFF;
			int temp = remainder * BASE_256 + digit256;
			number[i] = (byte) (temp / BASE_58);
			remainder = temp % BASE_58;
		}

		return (byte) remainder;
	}

	private static byte divmod256(byte[] number58, int startAt) {
		int remainder = 0;
		for (int i = startAt; i < number58.length; i++) {
			int digit58 = (int) number58[i] & 0xFF;
			int temp = remainder * BASE_58 + digit58;
			number58[i] = (byte) (temp / BASE_256);
			remainder = temp % BASE_256;
		}

		return (byte) remainder;
	}

	private static byte[] copyOfRange(byte[] source, int from, int to) {
		byte[] range = new byte[to - from];
		System.arraycopy(source, from, range, 0, range.length);
		return range;
	}
}

那么压缩UUID部分片段如下

public static String compressedUUID(UUID uuid) {
		byte[] byUuid = new byte[16];
		long least = uuid.getLeastSignificantBits();
		long most = uuid.getMostSignificantBits();
		long2bytes(most, byUuid, 0);
		long2bytes(least, byUuid, 8);
		String compressUUID = Base58.encode(byUuid);
		return compressUUID;
	}
protected static void long2bytes(long value, byte[] bytes, int offset) {
		for (int i = 7; i > -1; i--) {
			bytes[offset++] = (byte) ((value >> 8 * i) & 0xFF);
		}
	}

那么压缩出来的主键为22位，大大节省了存储和传输的效率，小样如下：
5Tg43HoVDUSwaF6yBf1qKY
3obyeMUYU6oYp97XbNzKuV
ChcHGBEvBw7JRM74i7yQAz
81ARiYeZaUyQTB6LTfdfAh
GtphVs8QZkyoBTcHTTpm5C
2q8jAT773mrsD8o1u2Rq4E
UTEuYET1ip9FUJbtJB4dy2
TFeEHsUXzJadFR1R22tGH2
3mFwsDFbhRQdDQ6cMTLYCd
P5CYVqutjRcr9bERUWE6RZ
SQYnrVq97cMNkb51UMNmQT