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| package cn.lili.common.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
| * <p>
| * 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);
| }
| }
|
|
