求帮忙修改上传代码（在linux系统下）

endPos = ((file.substring(0,boundaryLocation)).getBytes()).length;  

<%@ page contentType="text/html; charset=UTF-8" language="java" import="java.sql.*" errorPage="" %>   

<%@ page import="java.io.*"%>    

<%@ page import="java.util.*"%>    

<%@ page import="javax.servlet.*"%>    

<%@ page import="javax.servlet.http.*"%>    

<html>    

<head>    

<title> upFile </title>    

</head>    

<body bgcolor="#ffffff">    

<center>    

<%   

String rootPath;   

DataInputStream in = null;   

FileOutputStream fileOut = null;   

String realPath = request.getRealPath("/");   

rootPath = realPath + "/upload/";    

String contentType = request.getContentType();    

try{    

if(contentType.indexOf("multipart/form-data") >= 0){   

in = new DataInputStream(request.getInputStream());    

int formDataLength = request.getContentLength();    

byte dataBytes[] = new byte[formDataLength];    

int byteRead = 0;    

int totalBytesRead = 0;   

while(totalBytesRead < formDataLength){   

byteRead = in.read(dataBytes,totalBytesRead,formDataLength);    

totalBytesRead += byteRead;    

}    

String file = new String(dataBytes);   

String saveFile = file.substring(file.indexOf("filename=\"") + 10);    

  

saveFile = saveFile.substring(0,saveFile.indexOf("\n"));    

saveFile = saveFile.substring(saveFile.lastIndexOf("\\") + 1,saveFile.indexOf("\""));    

int lastIndex = contentType.lastIndexOf("=");    

String boundary = contentType.substring(lastIndex + 1,contentType.length());    

String fileName = rootPath + saveFile;   

int pos;    

pos = file.indexOf("filename=\"");    

pos = file.indexOf("\n",pos) + 1;    

pos = file.indexOf("\n",pos) + 1;    

pos = file.indexOf("\n",pos) + 1;    

int boundaryLocation = file.indexOf(boundary,pos) - 4;    

int startPos = ((file.substring(0,pos)).getBytes()).length;   

int endPos = ((file.substring(0,boundaryLocation)).getBytes()).length;    

File checkFile = new File(fileName);    

if(checkFile.exists()){   

return;   

}    

File fileDir = new File(rootPath);    

if(!fileDir.exists()){    

fileDir.mkdirs();    

}   

fileOut = new FileOutputStream(fileName);   

fileOut.write(dataBytes,startPos,(endPos - startPos));    

fileOut.close();    

}else{    

String content = request.getContentType();    

}    

}catch(Exception ex){    

throw new ServletException(ex.getMessage());    

}    

%>    

</center>    

</body>    

</html>