package me.zhyd.oauth.utils; import java.nio.charset.StandardCharsets; import java.util.concurrent.ThreadLocalRandom; /** * 高性能的创建UUID的工具类,https://github.com/lets-mica/mica * * @author yadong.zhang (yadong.zhang0415(a)gmail.com) * @since 1.9.3 */ public class UuidUtils { /** * All possible chars for representing a number as a String * copy from mica:https://github.com/lets-mica/mica/blob/master/mica-core/src/main/java/net/dreamlu/mica/core/utils/NumberUtil.java#L113 */ private final static byte[] 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' }; /** * 生成uuid,采用 jdk 9 的形式,优化性能 * copy from mica:https://github.com/lets-mica/mica/blob/master/mica-core/src/main/java/net/dreamlu/mica/core/utils/StringUtil.java#L335 *
* 关于mica uuid生成方式的压测结果,可以参考:https://github.com/lets-mica/mica-jmh/wiki/uuid * * @return UUID */ public static String getUUID() { ThreadLocalRandom random = ThreadLocalRandom.current(); long lsb = random.nextLong(); long msb = random.nextLong(); byte[] buf = new byte[32]; formatUnsignedLong(lsb, buf, 20, 12); formatUnsignedLong(lsb >>> 48, buf, 16, 4); formatUnsignedLong(msb, buf, 12, 4); formatUnsignedLong(msb >>> 16, buf, 8, 4); formatUnsignedLong(msb >>> 32, buf, 0, 8); return new String(buf, StandardCharsets.UTF_8); } /** * copy from mica:https://github.com/lets-mica/mica/blob/master/mica-core/src/main/java/net/dreamlu/mica/core/utils/StringUtil.java#L348 */ private static void formatUnsignedLong(long val, byte[] buf, int offset, int len) { int charPos = offset + len; int radix = 1 << 4; int mask = radix - 1; do { buf[--charPos] = DIGITS[((int) val) & mask]; val >>>= 4; } while (charPos > offset); } }