由UUID和短域名想到的
UUID是把128个二进制数，转换成32个16进制数的，每4个二进制数转换成一个16进制数。
如果是64（2的6次方）进制的话，应该是6个二进制数转换一个64进制数。
我们可以在UUID前面补加一个16进行数，让它成为33位的16进制数，共是132位二进制数。
这样就可以用22个64进制数表示132（22*6）位的二进制数。
结论是，可以把36位的UUID，去掉“-”变成32位的16进制数。
在这个数前面补一个16进制数，比如“0”，就变成了33位（132个二进制数，33*4）。
再把这个33位的16进制数，转换成22位的64进制数。
最终是把36位的UUID，变成一个22位的数表示，短了14位。
public class UUIDDemo {public static void main(String[] args) {String uuid = "1838efee-893d-3778-b480-43d6457767ea";System.out.println("原始uuid：" + uuid);uuid = uuid.replaceAll("-", "").toUpperCase();System.out.println("去掉'-'变大写:" + uuid);uuid = "0" + uuid;System.out.println("前补16进制'0':" + uuid);uuid = hexToBinary(uuid);System.out.println("转换为132位2进制数:" + uuid);uuid = binaryTo64(uuid);System.out.println("转换为64进制数:" + uuid);}public static String hexToBinary(String hex) {StringBuffer sb = new StringBuffer();if (hex == null || "".equals(hex))return "";for (int i = 0; i < hex.length(); i++) {sb.append(hexToBinary(hex.charAt(i)));}return sb.toString();}public static String hexToBinary(char hex) {String binary = null;switch (hex) {case '0':binary = "0000";break;case '1':binary = "0001";break;case '2':binary = "0010";break;case '3':binary = "0011";break;case '4':binary = "0100";break;case '5':binary = "0101";break;case '6':binary = "0110";break;case '7':binary = "0111";break;case '8':binary = "1000";break;case '9':binary = "1001";break;case 'A':binary = "1010";break;case 'B':binary = "1011";break;case 'C':binary = "1100";break;case 'D':binary = "1101";break;case 'E':binary = "1110";break;case 'F':binary = "1111";break;default:binary = "";}return binary;}public static String binaryTo64(String binary) {StringBuffer sb = new StringBuffer();if (binary == null || "".equals(binary))return "";if ((binary.length() % 6) != 0)return "";for (int i = 0; i < binary.length(); i += 6) {sb.append(binaryTo64a(binary.substring(i, i + 6)));}return sb.toString();}public static String binaryTo64a(String binary) {String result = null;if ("000000".equals(binary)) {result = "0";} else if ("000001".equals(binary)) {result = "1";} else if ("000010".equals(binary)) {result = "2";} else if ("000011".equals(binary)) {result = "3";} else if ("000100".equals(binary)) {result = "4";} else if ("000101".equals(binary)) {result = "5";} else if ("000110".equals(binary)) {result = "6";} else if ("000111".equals(binary)) {result = "7";} else if ("001000".equals(binary)) {result = "8";} else if ("001001".equals(binary)) {result = "9";} else if ("001010".equals(binary)) {result = "a";} else if ("001011".equals(binary)) {result = "b";} else if ("001100".equals(binary)) {result = "c";} else if ("001101".equals(binary)) {result = "d";} else if ("001110".equals(binary)) {result = "e";} else if ("001111".equals(binary)) {result = "f";} else if ("010000".equals(binary)) {result = "g";} else if ("010001".equals(binary)) {result = "h";} else if ("010010".equals(binary)) {result = "i";} else if ("010011".equals(binary)) {result = "j";} else if ("010100".equals(binary)) {result = "k";} else if ("010101".equals(binary)) {result = "l";} else if ("010110".equals(binary)) {result = "m";} else if ("010111".equals(binary)) {result = "n";} else if ("011000".equals(binary)) {result = "o";} else if ("011001".equals(binary)) {result = "p";} else if ("011010".equals(binary)) {result = "q";} else if ("011011".equals(binary)) {result = "r";} else if ("011100".equals(binary)) {result = "s";} else if ("011101".equals(binary)) {result = "t";} else if ("011110".equals(binary)) {result = "u";} else if ("011111".equals(binary)) {result = "v";} else if ("100000".equals(binary)) {result = "w";} else if ("100001".equals(binary)) {result = "x";} else if ("100010".equals(binary)) {result = "y";} else if ("100011".equals(binary)) {result = "z";} else if ("100100".equals(binary)) {result = "A";} else if ("100101".equals(binary)) {result = "B";} else if ("100110".equals(binary)) {result = "C";} else if ("100111".equals(binary)) {result = "D";} else if ("101000".equals(binary)) {result = "E";} else if ("101001".equals(binary)) {result = "F";} else if ("101010".equals(binary)) {result = "G";} else if ("101011".equals(binary)) {result = "H";} else if ("101100".equals(binary)) {result = "I";} else if ("101101".equals(binary)) {result = "J";} else if ("101110".equals(binary)) {result = "K";} else if ("101111".equals(binary)) {result = "L";} else if ("110000".equals(binary)) {result = "M";} else if ("110001".equals(binary)) {result = "N";} else if ("110010".equals(binary)) {result = "O";} else if ("110011".equals(binary)) {result = "P";} else if ("110100".equals(binary)) {result = "Q";} else if ("110101".equals(binary)) {result = "R";} else if ("110110".equals(binary)) {result = "S";} else if ("110111".equals(binary)) {result = "T";} else if ("111000".equals(binary)) {result = "U";} else if ("111001".equals(binary)) {result = "V";} else if ("111010".equals(binary)) {result = "W";} else if ("111011".equals(binary)) {result = "X";} else if ("111100".equals(binary)) {result = "Y";} else if ("111101".equals(binary)) {result = "Z";} else if ("111110".equals(binary)) {result = "_";} else if ("111111".equals(binary)) {result = "-";} else {result = "";}return result;}}
输出结果:
摘自：http://zhaiyz.iteye.com/blog/1018906
