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java 常用工具类,作为 apache-commons的补充

There is a newer version: 5.3.2302

package com.centit.support.algorithm;

import org.apache.commons.codec.binary.Base64;

import java.util.UUID;

@SuppressWarnings("unused")
public abstract class UuidOpt {

    private UuidOpt() {
        throw new IllegalAccessError("Utility class");
    }

    public static String digits(long val, int digits) {
        long hi = 1L << (digits * 4);
        return Long.toHexString(hi | (val & (hi - 1))).substring(1);
    }

    public static String uuidToString32(UUID uuid) {
        long leastSigBits = uuid.getLeastSignificantBits();
        long mostSigBits = uuid.getMostSignificantBits();
        return digits(mostSigBits >> 32, 8) +
            digits(mostSigBits, 8) +
            digits(leastSigBits >> 32, 8) +
            digits(leastSigBits, 8);
        //Long.toHexString(mostSigBits) + Long.toHexString(leastSigBits);
    }

    public static String uuidToString36(UUID uuid) {
        long leastSigBits = uuid.getLeastSignificantBits();
        long mostSigBits = uuid.getMostSignificantBits();
        return digits(mostSigBits >> 32, 8) + "-" +
            digits(mostSigBits >> 16, 4) + "-" +
            digits(mostSigBits, 4) + "-" +
            digits(leastSigBits >> 48, 4) + "-" +
            digits(leastSigBits, 12);
    }

    public static String uuidToBase64String(UUID uuid) {
        byte[] buf = new byte[16];
        ByteBaseOpt.writeInt64(buf, uuid.getMostSignificantBits(), 0);
        ByteBaseOpt.writeInt64(buf, uuid.getLeastSignificantBits(), 8);
        return new String(Base64.encodeBase64URLSafe(buf), 0, 22);
    }

    public static String getUuidAsString36() {
        return uuidToString36(UUID.randomUUID());
    }

    public static String getUuidAsString32() {
        return uuidToString32(UUID.randomUUID());
    }

    public static String getUuidAsBase64String() {
        return uuidToBase64String(UUID.randomUUID());
    }

    public static String getUuidAsString22() {
        return uuidToBase64String(UUID.randomUUID());
    }

    public static String getUuidAsString() {
        return uuidToString32(UUID.randomUUID());
    }
}