短网址就是将一个长网址转换成一个短网址，访问短网址会重定向到原来的长网址，短网址会更利于传播和推广。微博就会将我们发的长网址转换成短网址，
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微博将 https://www.cnblogs.com/strongmore/p/14520111.html 转换成了。
实现通过发号策略，每次来一个长网址，发一个号，这里我们使用SnowFlake（雪花算法）实现发号，然后转成62进制。
雪花算法 /** * 分布式Id生成器-雪花算法 */ public class SnowFlake { /** * 起始的时间戳 */ private final static long START_STMP = 1480166465631L; /** * 每一部分占用的位数 */ private final static long SEQUENCE_BIT = 12; //序列号占用的位数 private final static long MACHINE_BIT = 5; //机器标识占用的位数 private final static long DATACENTER_BIT = 5;//数据中心占用的位数 /** * 每一部分的最大值 */ private final static long MAX_DATACENTER_NUM = ~(-1L << DATACENTER_BIT); private final static long MAX_MACHINE_NUM = ~(-1L << MACHINE_BIT); private final static long MAX_SEQUENCE = ~(-1L << SEQUENCE_BIT); /** * 每一部分向左的位移 */ private final static long MACHINE_LEFT = SEQUENCE_BIT; private final static long DATACENTER_LEFT = SEQUENCE_BIT + MACHINE_BIT; private final static long TIMESTMP_LEFT = DATACENTER_LEFT + DATACENTER_BIT; private long datacenterId; //数据中心 private long machineId; //机器标识 private long sequence = 0L; //序列号 private long lastStmp = -1L;//上一次时间戳 public SnowFlake(long datacenterId, long machineId) { if (datacenterId > MAX_DATACENTER_NUM || datacenterId < 0) { throw new IllegalArgumentException( "datacenterId can\'t be greater than MAX_DATACENTER_NUM or less than 0"); } if (machineId > MAX_MACHINE_NUM || machineId < 0) { throw new IllegalArgumentException( "machineId can\'t be greater than MAX_MACHINE_NUM or less than 0"); } this.datacenterId = datacenterId; this.machineId = machineId; } /** * 产生下一个ID */ public synchronized long nextId() { long currStmp = getNewstmp(); if (currStmp < lastStmp) { throw new RuntimeException("Clock moved backwards. Refusing to generate id"); } if (currStmp == lastStmp) { //相同毫秒内，序列号自增 sequence = (sequence + 1) & MAX_SEQUENCE; //同一毫秒的序列数已经达到最大4096 if (sequence == 0L) { currStmp = getNextMill(); } } else { //不同毫秒内，序列号置为0 sequence = 0L; } lastStmp = currStmp; return (currStmp - START_STMP) << TIMESTMP_LEFT //时间戳部分 | datacenterId << DATACENTER_LEFT //数据中心部分 | machineId << MACHINE_LEFT //机器标识部分 | sequence; //序列号部分 } private long getNextMill() { long mill = getNewstmp(); while (mill <= lastStmp) { mill = getNewstmp(); } return mill; } private long getNewstmp() { return System.currentTimeMillis(); } public static void main(String[] args) { SnowFlake snowFlake = new SnowFlake(2, 3); for (int i = 0; i < (1 << 12); i++) { System.out.println(snowFlake.nextId()); } } } 转62进制 /** * 进制转换工具，最大支持十进制和62进制的转换 * 1、将十进制的数字转换为指定进制的字符串； * 2、将其它进制的数字（字符串形式）转换为十进制的数字 */ public class NumericConvertUtils { /** * 在进制表示中的字符集合，0-Z分别用于表示最大为62进制的符号表示 */ private static final char[] digits = {\'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\'}; /** * 将十进制的数字转换为指定进制的字符串 * * @param number 十进制的数字 * @param seed 指定的进制 * @return 指定进制的字符串 */ public static String toOtherNumberSystem(long number, int seed) { if (number < 0) { number = ((long) 2 * 0x7fffffff) + number + 2; } char[] buf = new char[32]; int charPos = 32; while ((number / seed) > 0) { buf[--charPos] = digits[(int) (number % seed)]; number /= seed; } buf[--charPos] = digits[(int) (number % seed)]; return new String(buf, charPos, (32 - charPos)); } /** * 将其它进制的数字（字符串形式）转换为十进制的数字 * * @param number 其它进制的数字（字符串形式） * @param seed 指定的进制，也就是参数str的原始进制 * @return 十进制的数字 */ public static long toDecimalNumber(String number, int seed) { char[] charBuf = number.toCharArray(); if (seed == 10) { return Long.parseLong(number); } long result = 0, base = 1; for (int i = charBuf.length - 1; i >= 0; i--) { int index = 0; for (int j = 0, length = digits.length; j < length; j++) { //找到对应字符的下标，对应的下标才是具体的数值 if (digits[j] == charBuf[i]) { index = j; } } result += index * base; base *= seed; } return result; } }