How to upload a large excel file

Dear sir ,
How to upload a large excel file and how to read a that large excel file or how to get a each column values from that large excel file.For small file i am getting values but for large file my code is not working so please help me sir i have used u r uploadandstore code for uploading and it is working fine but now i want to get a seperately each column values from that large file ,i used the following code.

/// For file uploading i have used the following code

String saveFile = "";
contentType = request.getContentType();
if ((contentType != null)
&& (contentType.indexOf("multipart/form-data") >= 0)) {
DataInputStream 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);
saveFile = file.substring(file.indexOf("filename=\"") + 10);
//System.out.println("saved file is " + saveFile);
saveFile = saveFile.substring(0, saveFile.indexOf("\n"));
//System.out.println("saved file is " + saveFile);
saveFile = saveFile.substring(saveFile.lastIndexOf("\\") + 1,
saveFile.indexOf("\""));
//System.out.println("saved file is " + saveFile);
int lastIndex = contentType.lastIndexOf("=");
String boundary = contentType.substring(lastIndex + 1,
contentType.length());
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;
startPos = ((file.substring(0, pos)).getBytes()).length;
endPos = ((file.substring(0, boundaryLocation)).getBytes()).length;
saveFile = "E:/workspace/harini/MassEmailSending/SmallProjectOnMassEmailSending/WebContent/file/" + saveFile;
System.out.println("saved file is "+saveFile);
File f = new File(saveFile);
FileOutputStream fileOut = new FileOutputStream(f);
fileOut.write(dataBytes, startPos, (endPos - startPos));
fileOut.flush();
fileOut.close();
}


/// For reading a excel file i used the following code with apache poi

if (filename != null && !filename.equals("")) {//1
try {//2
/*int l=0;
for(int i=0;i<arlMessage.size();i++){
String str = (String) arlMessage.get(i);
String s=str.replace("~","");
int intValue=Integer.parseInt(s);
intValue-=1;*/

FileInputStream fs = new FileInputStream(strFileAttachment);
Attachment = strFileAttachment.split("\n");
HSSFWorkbook wb = new HSSFWorkbook(fs);
for (int k = 0; k < wb.getNumberOfSheets(); k++) {//3
HSSFSheet sheet = wb.getSheetAt(k);
int rows = sheet.getPhysicalNumberOfRows();
for (int r = 1; r < rows; r++) {//4
HSSFRow row = sheet.getRow(r);
if (row != null) {//5
int cells = row.getPhysicalNumberOfCells();

// int l=0;
HSSFCell cell = row.getCell(0);
if (cell != null) {//6
//String value = null;
switch (cell.getCellType()) {//7
case HSSFCell.CELL_TYPE_FORMULA:
value = "FORMULA ";
break;

case HSSFCell.CELL_TYPE_NUMERIC:
value = "" + cell.getNumericCellValue();
break;

case HSSFCell.CELL_TYPE_STRING:
value = cell.getStringCellValue();
break;

default:
}//7
%><%--=value--%><input type="hidden" name="email" value="<%=value%>">


Using this code i am getting nothing values if i upload a large file ,if i upload a small file it works fine .Where my code going wrong i am not getting so please help me sir.


Thanks and Regards
Harini Veerapur.