ID生成工具

调用SequentialUuidHexGenerator.generate();

package id;

import java.net.InetAddress;

public abstract class AbstractUUIDGenerator {

    private static final int IP;
    static {
        int ipadd;
        try {
            ipadd = BytesHelper.toInt(InetAddress.getLocalHost().getAddress());
        } catch (Exception e) {
            ipadd = 0;
        }
        IP = ipadd;
    }

    private static short counter = (short)0;
    private static final int JVM = (int)(System.currentTimeMillis() >>> 8);

    public AbstractUUIDGenerator() {}

    protected static int getJVM() {
        return JVM;
    }

    protected static short getCount() {
        synchronized (AbstractUUIDGenerator.class) {
            if (counter < 0) {
                counter = 0;
            }
            return counter++;
        }
    }

    protected static int getIP() {
        return IP;
    }

    protected static short getHiTime() {
        return (short)(System.currentTimeMillis() >>> 32);
    }

    protected static int getLoTime() {
        return (int)System.currentTimeMillis();
    }
}

 

package id;

public final class BytesHelper {

    private BytesHelper() {}

    public static int toInt(byte[] bytes) {
        int result = 0;
        for (int i = 0; i < 4; i++) {
            result = (result << 8) - Byte.MIN_VALUE + (int)bytes[i];
        }
        return result;
    }
}

 

package id;

public class SequentialUuidHexGenerator extends AbstractUUIDGenerator{

    private static final String sep = "-";

    public static String generate() {
        return
                format( getJVM() ) + sep
                + format( getHiTime() ) + sep
                + format( getLoTime() ) + sep
                + format( getIP() ) + sep
                + format( getCount() );
    }

    protected static String format(int intValue) {
        String formatted = Integer.toHexString( intValue );
        StringBuilder buf = new StringBuilder( "00000000" );
        buf.replace( 8 - formatted.length(), 8, formatted );
        return buf.toString();
    }

    protected  static String format(short shortValue) {
        String formatted = Integer.toHexString( shortValue );
        StringBuilder buf = new StringBuilder( "0000" );
        buf.replace( 4 - formatted.length(), 4, formatted );
        return buf.toString();
    }
}

 

引自https://github.com/VictorBu/code-snippet/tree/master/java/sequential-uuid