Mega Code Archive
Create your own basic UUID
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/*
Derby - Class org.apache.derby.impl.services.uuid.BasicUUID
Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements. See the NOTICE file distributed with
this work for additional information regarding copyright ownership.
The ASF licenses this file to you under the Apache License, Version 2.0
(the "License"); you may not use this file except in compliance with
the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.io.StringReader;
public class BasicUUID {
/*
* * Fields of BasicUUID
*/
private long majorId; // only using 48 bits
private long timemillis;
private int sequence;
/*
* * Methods of BasicUUID
*/
/**
* Constructor only called by BasicUUIDFactory.
*/
public BasicUUID(long majorId, long timemillis, int sequence) {
this.majorId = majorId;
this.timemillis = timemillis;
this.sequence = sequence;
}
/**
* Constructor only called by BasicUUIDFactory. Constructs a UUID from the
* string representation produced by toString.
*
* @see BasicUUID#toString
*/
public BasicUUID(String uuidstring) {
StringReader sr = new StringReader(uuidstring);
sequence = (int) readMSB(sr);
long ltimemillis = readMSB(sr) << 32;
ltimemillis += readMSB(sr) << 16;
ltimemillis += readMSB(sr);
timemillis = ltimemillis;
majorId = readMSB(sr);
}
/**
* Constructor only called by BasicUUIDFactory. Constructs a UUID from the
* byte array representation produced by toByteArrayio.
*
* @see BasicUUID#toByteArray
*/
public BasicUUID(byte[] b) {
int lsequence = 0;
for (int ix = 0; ix < 4; ix++) {
lsequence = lsequence << 8;
lsequence = lsequence | (0xff & b[ix]);
}
long ltimemillis = 0;
for (int ix = 4; ix < 10; ix++) {
ltimemillis = ltimemillis << 8;
ltimemillis = ltimemillis | (0xff & b[ix]);
}
long linetaddr = 0;
for (int ix = 10; ix < 16; ix++) {
linetaddr = linetaddr << 8;
linetaddr = linetaddr | (0xff & b[ix]);
}
sequence = lsequence;
timemillis = ltimemillis;
majorId = linetaddr;
}
/*
* Formatable methods
*/
// no-arg constructor, required by Formatable
public BasicUUID() {
super();
}
/**
* Write this out.
*
* @exception IOException
* error writing to log stream
*/
public void writeExternal(ObjectOutput out) throws IOException {
// RESOLVE: write out the byte array instead?
out.writeLong(majorId);
out.writeLong(timemillis);
out.writeInt(sequence);
}
/**
* Read this in
*
* @exception IOException
* error reading from log stream
*/
public void readExternal(ObjectInput in) throws IOException {
majorId = in.readLong();
timemillis = in.readLong();
sequence = in.readInt();
}
private static void writeMSB(char[] data, int offset, long value, int nbytes) {
for (int i = nbytes - 1; i >= 0; i--) {
long b = (value & (255L << (8 * i))) >>> (8 * i);
int c = (int) ((b & 0xf0) >> 4);
data[offset++] = (char) (c < 10 ? c + '0' : (c - 10) + 'a');
c = (int) (b & 0x0f);
data[offset++] = (char) (c < 10 ? c + '0' : (c - 10) + 'a');
}
}
/**
* Read a long value, msb first, from its character representation in the
* string reader, using '-' or end of string to delimit.
*/
private static long readMSB(StringReader sr) {
long value = 0;
try {
int c;
while ((c = sr.read()) != -1) {
if (c == '-')
break;
value <<= 4;
int nibble;
if (c <= '9')
nibble = c - '0';
else if (c <= 'F')
nibble = c - 'A' + 10;
else
nibble = c - 'a' + 10;
value += nibble;
}
} catch (Exception e) {
}
return value;
}
/*
* * Methods of UUID
*/
/**
* Implement value equality.
*
*/
public boolean equals(Object otherObject) {
if (!(otherObject instanceof BasicUUID))
return false;
BasicUUID other = (BasicUUID) otherObject;
return (this.sequence == other.sequence) && (this.timemillis == other.timemillis)
&& (this.majorId == other.majorId);
}
/**
* Provide a hashCode which is compatible with the equals() method.
*/
public int hashCode() {
long hc = majorId ^ timemillis;
return sequence ^ ((int) (hc >> 4));
}
/**
* Produce a string representation of this UUID which can be passed to
* UUIDFactory.recreateUUID later on to reconstruct it. The funny
* representation is designed to (sort of) match the format of Microsoft's
* UUIDGEN utility.
*/
public String toString() {
return stringWorkhorse('-');
}
/**
* Produce a string representation of this UUID which is suitable for use as a
* unique ANSI identifier.
*/
public String toANSIidentifier() {
return "U" + stringWorkhorse('X');
}
/**
* Private workhorse of the string making routines.
*
* @param separator
* Character to separate number blocks. Null means do not include a
* separator.
*
* @return string representation of UUID.
*/
public String stringWorkhorse(char separator) {
char[] data = new char[36];
writeMSB(data, 0, (long) sequence, 4);
int offset = 8;
if (separator != 0)
data[offset++] = separator;
long ltimemillis = timemillis;
writeMSB(data, offset, (ltimemillis & 0x0000ffff00000000L) >>> 32, 2);
offset += 4;
if (separator != 0)
data[offset++] = separator;
writeMSB(data, offset, (ltimemillis & 0x00000000ffff0000L) >>> 16, 2);
offset += 4;
if (separator != 0)
data[offset++] = separator;
writeMSB(data, offset, (ltimemillis & 0x000000000000ffffL), 2);
offset += 4;
if (separator != 0)
data[offset++] = separator;
writeMSB(data, offset, majorId, 6);
offset += 12;
return new String(data, 0, offset);
}
/**
* Store this UUID in a byte array. Arrange the bytes in the UUID in the same
* order the code which stores a UUID in a string does.
*
* @see org.apache.derby.catalog.UUID#toByteArray
*/
public byte[] toByteArray() {
byte[] result = new byte[16];
int lsequence = sequence;
result[0] = (byte) (lsequence >>> 24);
result[1] = (byte) (lsequence >>> 16);
result[2] = (byte) (lsequence >>> 8);
result[3] = (byte) lsequence;
long ltimemillis = timemillis;
result[4] = (byte) (ltimemillis >>> 40);
result[5] = (byte) (ltimemillis >>> 32);
result[6] = (byte) (ltimemillis >>> 24);
result[7] = (byte) (ltimemillis >>> 16);
result[8] = (byte) (ltimemillis >>> 8);
result[9] = (byte) ltimemillis;
long linetaddr = majorId;
result[10] = (byte) (linetaddr >>> 40);
result[11] = (byte) (linetaddr >>> 32);
result[12] = (byte) (linetaddr >>> 24);
result[13] = (byte) (linetaddr >>> 16);
result[14] = (byte) (linetaddr >>> 8);
result[15] = (byte) linetaddr;
return result;
}
/**
* Clone this UUID.
*
* @return a copy of this UUID
*/
public BasicUUID cloneMe() {
return new BasicUUID(majorId, timemillis, sequence);
}
public String toHexString() {
return stringWorkhorse((char) 0);
}
}
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