yadong.zhang
66 lines
2.3 KiB
Java
66 lines
2.3 KiB
Java
package me.zhyd.oauth.utils;
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import java.nio.charset.StandardCharsets;
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import java.util.concurrent.ThreadLocalRandom;
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/**
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* 高性能的创建UUID的工具类，https://github.com/lets-mica/mica
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*
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* @author yadong.zhang (yadong.zhang0415(a)gmail.com)
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* @since 1.9.3
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*/
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public class UuidUtils {
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/**
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* All possible chars for representing a number as a String
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* copy from mica：https://github.com/lets-mica/mica/blob/master/mica-core/src/main/java/net/dreamlu/mica/core/utils/NumberUtil.java#L113
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*/
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private final static byte[] DIGITS = {
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'0', '1', '2', '3', '4', '5',
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'6', '7', '8', '9', 'a', 'b',
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'c', 'd', 'e', 'f', 'g', 'h',
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'i', 'j', 'k', 'l', 'm', 'n',
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'o', 'p', 'q', 'r', 's', 't',
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'u', 'v', 'w', 'x', 'y', 'z',
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'A', 'B', 'C', 'D', 'E', 'F',
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'G', 'H', 'I', 'J', 'K', 'L',
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'M', 'N', 'O', 'P', 'Q', 'R',
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'S', 'T', 'U', 'V', 'W', 'X',
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'Y', 'Z'
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};
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/**
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* 生成uuid，采用 jdk 9 的形式，优化性能
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* copy from mica：https://github.com/lets-mica/mica/blob/master/mica-core/src/main/java/net/dreamlu/mica/core/utils/StringUtil.java#L335
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* <p>
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* 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
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*
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* @return UUID
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*/
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public static String getUUID() {
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ThreadLocalRandom random = ThreadLocalRandom.current();
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long lsb = random.nextLong();
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long msb = random.nextLong();
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byte[] buf = new byte[32];
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formatUnsignedLong(lsb, buf, 20, 12);
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formatUnsignedLong(lsb >>> 48, buf, 16, 4);
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formatUnsignedLong(msb, buf, 12, 4);
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formatUnsignedLong(msb >>> 16, buf, 8, 4);
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formatUnsignedLong(msb >>> 32, buf, 0, 8);
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return new String(buf, StandardCharsets.UTF_8);
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}
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/**
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* copy from mica：https://github.com/lets-mica/mica/blob/master/mica-core/src/main/java/net/dreamlu/mica/core/utils/StringUtil.java#L348
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*/
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private static void formatUnsignedLong(long val, byte[] buf, int offset, int len) {
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int charPos = offset + len;
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int radix = 1 << 4;
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int mask = radix - 1;
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do {
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buf[--charPos] = DIGITS[((int) val) & mask];
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val >>>= 4;
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} while (charPos > offset);
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}
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}
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