Java web中上传文件的重命名

package com.xiaowei;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Random;

public class IPTimeStamp {
private SimpleDateFormat sdf=null;
private String ip=null;
public IPTimeStamp(String ip){
this.ip=ip;

}
public String getDate(){
this.sdf= new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
return this.sdf.format(new Date());
}
public  String getTimeStamp()
{
this.sdf=new SimpleDateFormat("yyyyMMddHHmmssSSSS");
return this.sdf.format(new Date());
}
private String addZero (String str,int len){
StringBuffer s=new StringBuffer();
s.append(str);
while(s.length()<len){
s.insert(0,"0");

}
return s.toString();
}

public String getIPTimeRand(){
StringBuffer buf =new StringBuffer();
if(this.ip!=null){
String[] s=this.ip.split("\\.");
for (int i = 0; i < s.length; i++) {
buf.append(this.addZero(s[i], 3));

}

}
buf.append(this.getTimeStamp());
Random r= new Random();
for (int i = 0; i < 3; i++) {
buf.append(r.nextInt(10));
}
return buf.toString();
}
<span style="white-space:pre">		</span>//一个简单的测试程序
public static void main(String[] args) {
System.out.println(new IPTimeStamp("192.168.1.1").getIPTimeRand());
}
}