org.apache.poi.poifs.filesystem
Class POIFSFileSystem

java.lang.Object
  org.apache.poi.poifs.filesystem.POIFSFileSystem

All Implemented Interfaces:

POIFSViewable

public class POIFSFileSystem
extends java.lang.Object
implements POIFSViewable

This is the main class of the POIFS system; it manages the entire life cycle of the filesystem.

Author:

Marc Johnson (mjohnson at apache dot org)

Constructor Summary

POIFSFileSystem()
Constructor, intended for writing

POIFSFileSystem(java.io.InputStream stream)
Create a POIFSFileSystem from an InputStream.

Method Summary

DirectoryEntry	createDirectory(java.lang.String name) create a new DirectoryEntry in the root directory
DocumentEntry	createDocument(java.io.InputStream stream, java.lang.String name) Create a new document to be added to the root directory
DocumentEntry	createDocument(java.lang.String name, int size, POIFSWriterListener writer) create a new DocumentEntry in the root entry; the data will be provided later
DocumentInputStream	createDocumentInputStream(java.lang.String documentName) open a document in the root entry's list of entries
static java.io.InputStream	createNonClosingInputStream(java.io.InputStream is) Convenience method for clients that want to avoid the auto-close behaviour of the constructor.
int	getBigBlockSize()
DirectoryNode	getRoot() get the root entry
java.lang.String	getShortDescription() Provides a short description of the object, to be used when a POIFSViewable object has not provided its contents.
java.lang.Object[]	getViewableArray() Get an array of objects, some of which may implement POIFSViewable
java.util.Iterator	getViewableIterator() Get an Iterator of objects, some of which may implement POIFSViewable
static boolean	hasPOIFSHeader(java.io.InputStream inp) Checks that the supplied InputStream (which MUST support mark and reset, or be a PushbackInputStream) has a POIFS (OLE2) header at the start of it.
static void	main(java.lang.String[] args) read in a file and write it back out again
boolean	preferArray() Give viewers a hint as to whether to call getViewableArray or getViewableIterator
void	writeFilesystem(java.io.OutputStream stream) Write the filesystem out

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

POIFSFileSystem

public POIFSFileSystem()

Constructor, intended for writing

POIFSFileSystem

public POIFSFileSystem(java.io.InputStream stream)
                throws java.io.IOException

Create a POIFSFileSystem from an InputStream. Normally the stream is read until EOF. The stream is always closed.

Some streams are usable after reaching EOF (typically those that return true for markSupported()). In the unlikely case that the caller has such a stream and needs to use it after this constructor completes, a work around is to wrap the stream in order to trap the close() call. A convenience method ( createNonClosingInputStream()) has been provided for this purpose:

 InputStream wrappedStream = POIFSFileSystem.createNonClosingInputStream(is);
 HSSFWorkbook wb = new HSSFWorkbook(wrappedStream);
 is.reset(); 
 doSomethingElse(is); 
 

Note also the special case of ByteArrayInputStream for which the close() method does nothing.

 ByteArrayInputStream bais = ...
 HSSFWorkbook wb = new HSSFWorkbook(bais); // calls bais.close() !
 bais.reset(); // no problem
 doSomethingElse(bais);
 

Parameters:

stream - the InputStream from which to read the data

Throws:

java.io.IOException - on errors reading, or on invalid data

Method Detail

createNonClosingInputStream

public static java.io.InputStream createNonClosingInputStream(java.io.InputStream is)

Convenience method for clients that want to avoid the auto-close behaviour of the constructor.

hasPOIFSHeader

public static boolean hasPOIFSHeader(java.io.InputStream inp)
                              throws java.io.IOException

Checks that the supplied InputStream (which MUST support mark and reset, or be a PushbackInputStream) has a POIFS (OLE2) header at the start of it. If your InputStream does not support mark / reset, then wrap it in a PushBackInputStream, then be sure to always use that, and not the original!

Parameters:

inp - An InputStream which supports either mark/reset, or is a PushbackInputStream

Throws:

java.io.IOException

createDocument

public DocumentEntry createDocument(java.io.InputStream stream,
                                    java.lang.String name)
                             throws java.io.IOException

Create a new document to be added to the root directory

Parameters:

stream - the InputStream from which the document's data will be obtained

name - the name of the new POIFSDocument

Returns:

the new DocumentEntry

Throws:

java.io.IOException - on error creating the new POIFSDocument

createDocument

public DocumentEntry createDocument(java.lang.String name,
                                    int size,
                                    POIFSWriterListener writer)
                             throws java.io.IOException

create a new DocumentEntry in the root entry; the data will be provided later

Parameters:

name - the name of the new DocumentEntry

size - the size of the new DocumentEntry

writer - the writer of the new DocumentEntry

Returns:

the new DocumentEntry

Throws:

java.io.IOException

createDirectory

public DirectoryEntry createDirectory(java.lang.String name)
                               throws java.io.IOException

create a new DirectoryEntry in the root directory

Parameters:

name - the name of the new DirectoryEntry

Returns:

the new DirectoryEntry

Throws:

java.io.IOException - on name duplication

writeFilesystem

public void writeFilesystem(java.io.OutputStream stream)
                     throws java.io.IOException

Write the filesystem out

Parameters:

stream - the OutputStream to which the filesystem will be written

Throws:

java.io.IOException - thrown on errors writing to the stream

main

public static void main(java.lang.String[] args)
                 throws java.io.IOException

read in a file and write it back out again

Parameters:

args - names of the files; arg[ 0 ] is the input file, arg[ 1 ] is the output file

Throws:

java.io.IOException

getRoot

public DirectoryNode getRoot()

get the root entry

Returns:

the root entry

createDocumentInputStream

public DocumentInputStream createDocumentInputStream(java.lang.String documentName)
                                              throws java.io.IOException

open a document in the root entry's list of entries

Parameters:

documentName - the name of the document to be opened

Returns:

a newly opened DocumentInputStream

Throws:

java.io.IOException - if the document does not exist or the name is that of a DirectoryEntry

getViewableArray

public java.lang.Object[] getViewableArray()

Get an array of objects, some of which may implement POIFSViewable

Specified by:

getViewableArray in interface POIFSViewable

Returns:

an array of Object; may not be null, but may be empty

getViewableIterator

public java.util.Iterator getViewableIterator()

Get an Iterator of objects, some of which may implement POIFSViewable

Specified by:

getViewableIterator in interface POIFSViewable

Returns:

an Iterator; may not be null, but may have an empty back end store

preferArray

public boolean preferArray()

Give viewers a hint as to whether to call getViewableArray or getViewableIterator

Specified by:

preferArray in interface POIFSViewable

Returns:

true if a viewer should call getViewableArray, false if a viewer should call getViewableIterator

getShortDescription

public java.lang.String getShortDescription()

Provides a short description of the object, to be used when a POIFSViewable object has not provided its contents.

Specified by:

getShortDescription in interface POIFSViewable

Returns:

short description

getBigBlockSize

public int getBigBlockSize()

Returns:

The Big Block size, normally 512 bytes, sometimes 4096 bytes