unable to read file header

[Sanjay Chougule]

hi all ,
my problem is related with file Header
in my jsp application i am uploading excel sheet using "apache.poi"
for validation when i m open & chek file it work fine , but next time when i read same file again ..... then following exception occur .....

-------------------------------------------------------------------------------------
Unable to read entire header; 0 bytes read; expected 512 bytes
at org.apache.poi.poifs.storage.HeaderBlockReader.<init>(HeaderBlockReader.java:83)
-------------------------------------------------------------------------------------
is this problem related with file header ...??
thanks in advance ,

[Ernest Friedman-Hill]

When you try to open the file the second time, is it still there? Or have you accidentally truncated it by opening it for writing (i.e., with a FileWriter?)

[Sanjay Chougule]

thanks Ernest !
yes , file is there no any other operation with that .
but second time when i assign this fileStream to
.----------------------------------------------
fileSystem = new POIFSFileSystem(fileStream );
----------------------------------------------
now i m getting that error ....

[Ilja Preuss]

Do you mean you are reusing the same stream, the one you have already read from?

[Sanjay Chougule]

yes i am reusing ...

[Sanjay Chougule]

hi ! ,
i just want to add some lines ....
i receive input stream as follow
-------------------------------------------------
InputStream f1 = (InputStream) request.getAttribute("fileStream");
-------------------------------------------------
this one is one excel file ...
now pass this 'f1'

method1(f1);// here i m takiing 'f1' as InputStream or FileInputStream (by typecasting 'f1')

in method1 i am able to read input stream using apache api
suppose i pass this inputStream again to 'method1()' it gives error ...

[William Brogden]

You cant reuse the same file stream - it is positioned at the end-of-file. Just open a new one.

Bill

[Sanjay Chougule]

is there no any other way except reopen the file ,
as i explain last post
i store that requist in two different InputStream , but it gives same error

i have also copied that inputstream in another inputstream , but it not work
[ May 12, 2008: Message edited by: Sanjay Chougule ]

[Ernest Friedman-Hill]

When you get the Excel data from the client, save it to a temporary file on the server; then you can open it as many times as you need to.

[Sanjay Chougule]

Hi Ernest !!!
I have also tried same thing , i.e. copy client data at server & reuse it but reusing second time it gives same error �.
This inputstream also not support mark() & reset() methods .

[Ilja Preuss]

Read the content of the stream into a byte array, and then pass a ByteArrayInputStream into those methods. Use a new ByteArrayInputStream for each method call, and reuse the byte array.