上传Excel文件时，可以实现上传，但上传后的新文件打开报发现有不可读取的内容，怎么回事！代码如下:(求大神指导)
String remoteAddr = request.getRemoteAddr();
String serverName = request.getServerName();
String realPath = request.getRealPath(serverName);
realPath = realPath.substring(0,realPath.lastIndexOf("\\"));
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;
//out.print(fileName);
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()){
out.println( "文件已经存在");
}
File fileDir = new File(rootPath);
if(!fileDir.exists()){
fileDir.mkdirs();
}
fileOut = new FileOutputStream(fileName);
fileOut.write(dataBytes,startPos,(endPos - startPos));
fileOut.close();