package org.jeecg.common.util;
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import java.net.InetAddress;
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/**
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*
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* @Author 张代浩
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*
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*/
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public class UUIDGenerator {
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/**
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* 产生一个32位的UUID
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*
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* @return
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*/
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public static String generate() {
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return new StringBuilder(32).append(format(getIp())).append(
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format(getJvm())).append(format(getHiTime())).append(
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format(getLoTime())).append(format(getCount())).toString();
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}
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private static final int IP;
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static {
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int ipadd;
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try {
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ipadd = toInt(InetAddress.getLocalHost().getAddress());
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} catch (Exception e) {
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ipadd = 0;
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}
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IP = ipadd;
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}
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private static short counter = (short) 0;
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private static final int JVM = (int) (System.currentTimeMillis() >>> 8);
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private final static String format(int intval) {
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String formatted = Integer.toHexString(intval);
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StringBuilder buf = new StringBuilder("00000000");
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buf.replace(8 - formatted.length(), 8, formatted);
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return buf.toString();
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}
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private final static String format(short shortval) {
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String formatted = Integer.toHexString(shortval);
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StringBuilder buf = new StringBuilder("0000");
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buf.replace(4 - formatted.length(), 4, formatted);
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return buf.toString();
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}
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private final static int getJvm() {
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return JVM;
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}
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private final static short getCount() {
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synchronized (UUIDGenerator.class) {
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if (counter < 0) {
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counter = 0;
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}
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return counter++;
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}
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}
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/**
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* Unique in a local network
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*/
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private final static int getIp() {
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return IP;
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}
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/**
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* Unique down to millisecond
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*/
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private final static short getHiTime() {
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return (short) (System.currentTimeMillis() >>> 32);
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}
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private final static int getLoTime() {
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return (int) System.currentTimeMillis();
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}
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private final static int toInt(byte[] bytes) {
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int result = 0;
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int length = 4;
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for (int i = 0; i < length; i++) {
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result = (result << 8) - Byte.MIN_VALUE + (int) bytes[i];
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}
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return result;
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}
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}
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