生成一个32位的UUID

coding如下：

package cn.migu.utils;

import java.net.InetAddress;
import java.util.UUID;

import org.junit.Test;

/**
* <Description> 获取随机数方法封装
* @author YanLu
*
*/
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();
}

/**
* 生成系统默认的UUID
*
* @return
*/
public static String generateUUID() {
return UUID.randomUUID().toString().replaceAll("-", "");
}

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;
}

/**
* 测试代码
*/
@Test
public void getUUID(){
String id = UUIDGenerator.generate();
System.out.println(id);
}

}