通常我們生成的uuid都是128位，以36/32位十六進制表示纵竖。長度過長肩杈，但真正要壓縮它的原因是由于我方平臺需要與對方平臺傳遞這個uuid，二對方平臺支持的最大長度是30位堪伍。

ps 若是用作數(shù)據(jù)庫主鍵的話還是比較推薦Twitter的SnowFlake算法锚烦，長度才64位，比uuid短了一半杠娱；

壓縮原理：使用base64將原來4位編碼為1字符的方式變?yōu)?位為一字符挽牢，將原uuid的分隔符 -去掉，使用無填充的base64可編碼為22字符長度摊求；

public class UUIDUtil {
/**
 * 壓縮
 * @param src uuid字符串禽拔，可帶有{@code -}
 * @return base64字符串，length=22
 */
public static String compress(String src) {
    UUID uuid = UUID.fromString(src);
    long msb = uuid.getMostSignificantBits();
    long lsb = uuid.getLeastSignificantBits();

    byte[] b = new byte[16];
    for (int i = 0; i < 8; i++) {
        b[i] = (byte) (msb >>> (8 * (7-i)) & 0xff);
        b[i+8] = (byte) (lsb >>> (8 * (7-i)) & 0xff);
    }
    
    return Base64.getEncoder().withoutPadding().encodeToString(b);
}

/**
 * 解壓
 * @param src base64字符串，length=22
 * @return uuid字符串睹栖，{@code -}分割
 */
public static String decompress(String src) {
    byte[] b = Base64.getDecoder().decode(src);

    long msb = 0;
    long lsb = 0;
    for (int i=0; i<8; i++) {
        msb = (msb << 8) | (b[i] & 0xff);
        lsb = (lsb << 8) | (b[i+8] & 0xff);
    }

    return new UUID(msb, lsb).toString();
}

UUID中硫惕，使用兩個long類型變量mostSigBits（msb）、leastSigBits（lsb）分別表示高64位與低64位野来；以上代碼中compress(String src)方法參數(shù)只能是以-分割的36位uuid恼除，若要兼容32位uuid，將該方法該為一下代碼曼氛。原理可參見UUID.fromString(String name)方法豁辉；

/**
 * 壓縮
 * @param src uuid字符串，可帶有{@code -}
 * @return base64字符串舀患，length=22
 */
public static String compress(String src) {
    String[] components = src.split("-");
    if (components.length != 5) {
        components = new String[5];
        src = src.replace("-", "");

        components[0] = src.substring(0, 8);
        components[1] = src.substring(8, 12);
        components[2] = src.substring(12, 16);
        components[3] = src.substring(16, 20);
        components[4] = src.substring(20, 32);
    }

    for (int i=0; i<5; i++)
        components[i] = "0x"+components[i];

    long msb = Long.decode(components[0]).longValue();
    msb <<= 16;
    msb |= Long.decode(components[1]).longValue();
    msb <<= 16;
    msb |= Long.decode(components[2]).longValue();

    long lsb = Long.decode(components[3]).longValue();
    lsb <<= 48;
    lsb |= Long.decode(components[4]).longValue();

    byte[] b = new byte[16];
    for (int i = 0; i < 8; i++) {
        b[i] = (byte) (msb >>> (8 * (7-i)) & 0xff);
        b[i+8] = (byte) (lsb >>> (8 * (7-i)) & 0xff);
    }

    return Base64.getEncoder().withoutPadding().encodeToString(b);
}