content: package org.jeecg.common.util;
  
  
  import java.net.InetAddress;
  
  /**
   * 
   * @Author  张代浩
   *
   */
  public class UUIDGenerator {
  
  	
  	/**
  	 * 产生一个32位的UUID
  	 * 
  	 * @return
  	 */
  
  	public static String generate() {
  		return new StringBuilder(32).append(format(getIP())).append(
  				format(getJVM())).append(format(getHiTime())).append(
  				format(getLoTime())).append(format(getCount())).toString();
  		
  	}
  
  	private static final int IP;
  	static {
  		int ipadd;
  		try {
  			ipadd = 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);
  
  	private final static String format(int intval) {
  		String formatted = Integer.toHexString(intval);
  		StringBuilder buf = new StringBuilder("00000000");
  		buf.replace(8 - formatted.length(), 8, formatted);
  		return buf.toString();
  	}
  
  	private final static String format(short shortval) {
  		String formatted = Integer.toHexString(shortval);
  		StringBuilder buf = new StringBuilder("0000");
  		buf.replace(4 - formatted.length(), 4, formatted);
  		return buf.toString();
  	}
  
  	private final static int getJVM() {
  		return JVM;
  	}
  
  	private final static short getCount() {
  		synchronized (UUIDGenerator.class) {
  			if (counter < 0) {
  				counter = 0;
  			}
  			return counter++;
  		}
  	}
  
  	/**
  	 * Unique in a local network
  	 */
  	private final static int getIP() {
  		return IP;
  	}
  
  	/**
  	 * Unique down to millisecond
  	 */
  	private final static short getHiTime() {
  		return (short) (System.currentTimeMillis() >>> 32);
  	}
  
  	private final static int getLoTime() {
  		return (int) System.currentTimeMillis();
  	}
  
  	private final 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;
  	}
  
  }
  