java 파일 저장할때.. 중복이름 체크

package struts02.util;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Date;

import org.apache.struts.upload.FormFile;

public class BoardUtil {

 public static String saveFile(FormFile uploadFile) {
  String physicalFileName=null;
  InputStream is;
  try {
   is = uploadFile.getInputStream();
   String uploadFileName = uploadFile.getFileName();
   physicalFileName = getPhysicalFileName( uploadFileName );
   String filePath = "F:/Struts_And_iBatis/workspace/struts-board-02/WebContent/upload/";
   OutputStream os = new FileOutputStream(filePath + physicalFileName);

   int byteRead = 0;
   byte[] buf = new byte[8192];
   while ((byteRead = is.read(buf)) != -1) {
    os.write(buf, 0, byteRead);
   }
   os.close();
   is.close();
  } catch (Exception e) {
   e.printStackTrace();
  }
  return physicalFileName;
 }//end saveFile()

 private static String getPhysicalFileName(String uploadFileName) {
  String systemTime=new Date().getTime()+"";//
  if( uploadFileName.indexOf(".") == -1 ){ //파일이름에 .이 없으면
   return uploadFileName+"_"+systemTime;
  }else{
   int index = uploadFileName.lastIndexOf(".");
   //확장자를뺀파일명
   String _tmpFileName = uploadFileName.substring(0, index);
   // Extension
   String _extName = uploadFileName.substring( index );
   return _tmpFileName + "_"+systemTime+_extName;
  }
 }

}