org.apache.commons.vfs
Interface FileObject

All Known Implementing Classes:

AbstractFileObject, CompressedFileFileObject, DecoratedFileObject, LocalFile, RamFileObject, SftpFileObject, TarFileObject, UrlFileObject, ZipFileObject

public interface FileObject

Represents a file, and is used to access the content and structure of the file.

Files are arranged in a hierarchy. Each hierachy forms a file system. A file system represents things like a local OS file system, a windows share, an HTTP server, or the contents of a Zip file.

There are two types of files: Folders, which contain other files, and normal files, which contain data, or content. A folder may not have any content, and a normal file cannot contain other files.

File Naming

TODO - write this.

Reading and Writing a File

Reading and writing a file, and all other operations on the file's content, is done using the FileContent object returned by getContent().

Creating and Deleting a File

A file is created using either createFolder(), createFile(), or by writing to the file using one of the FileContent methods.

A file is deleted using delete(). Recursive deletion can be done using delete(FileSelector).

Finding Files

Other files in the same file system as this file can be found using:

• resolveFile(java.lang.String, org.apache.commons.vfs.NameScope) to find another file relative to this file.
• getChildren() and getChild(java.lang.String) to find the children of this file.
• getParent() to find the folder containing this file.
• getFileSystem() to find another file in the same file system.

To find files in another file system, use a FileSystemManager.

Version:

$Revision: 483899 $ $Date: 2006-12-08 10:47:09 +0100 (Fr, 08 Dez 2006) $

Author:

Adam Murdoch

See Also:

FileSystemManager, FileContent, FileName

Method Summary

boolean	canRenameTo(FileObject newfile) Queries the file if it is possible to rename it to newfile.
void	close() Closes this file, and its content.
void	copyFrom(FileObject srcFile, FileSelector selector) Copies another file, and all its descendents, to this file.
void	createFile() Creates this file, if it does not exist.
void	createFolder() Creates this folder, if it does not exist.
boolean	delete() Deletes this file.
int	delete(FileSelector selector) Deletes all descendents of this file that match a selector.
boolean	exists() Determines if this file exists.
FileObject[]	findFiles(FileSelector selector) Finds the set of matching descendents of this file, in depthwise order.
void	findFiles(FileSelector selector, boolean depthwise, List selected) Finds the set of matching descendents of this file.
FileObject	getChild(String name) Returns a child of this file.
FileObject[]	getChildren() Lists the children of this file.
FileContent	getContent() Returns this file's content.
FileOperations	getFileOperations()
FileSystem	getFileSystem() Returns the file system that contains this file.
FileName	getName() Returns the name of this file.
FileObject	getParent() Returns the folder that contains this file.
FileType	getType() Returns this file's type.
URL	getURL() Returns a URL representing this file.
boolean	isAttached() check if the fileObject is attaced
boolean	isContentOpen() check if someone reads/write to this file
boolean	isHidden() Determines if this file is hidden.
boolean	isReadable() Determines if this file can be read.
boolean	isWriteable() Determines if this file can be written to.
void	moveTo(FileObject destFile) Move this file.
void	refresh() This will prepare the fileObject to get resynchronized with the underlaying filesystem if required
FileObject	resolveFile(String path) Finds a file, relative to this file.
FileObject	resolveFile(String name, NameScope scope) Finds a file, relative to this file.

Method Detail

getName

public FileName getName()

Returns the name of this file.

getURL

public URL getURL()
           throws FileSystemException

Returns a URL representing this file.

Throws:

FileSystemException

exists

public boolean exists()
               throws FileSystemException

Determines if this file exists.

Returns:

true if this file exists, false if not.

Throws:

FileSystemException - On error determining if this file exists.

isHidden

public boolean isHidden()
                 throws FileSystemException

Determines if this file is hidden.

Returns:

true if this file is hidden, false if not.

Throws:

FileSystemException - On error determining if this file exists.

isReadable

public boolean isReadable()
                   throws FileSystemException

Determines if this file can be read.

Returns:

true if this file is readable, false if not.

Throws:

FileSystemException - On error determining if this file exists.

isWriteable

public boolean isWriteable()
                    throws FileSystemException

Determines if this file can be written to.

Returns:

true if this file is writeable, false if not.

Throws:

FileSystemException - On error determining if this file exists.

getType

public FileType getType()
                 throws FileSystemException

Returns this file's type.

Returns:

One of the FileType constants. Never returns null.

Throws:

FileSystemException - On error determining the file's type.

getParent

public FileObject getParent()
                     throws FileSystemException

Returns the folder that contains this file.

Returns:

The folder that contains this file. Returns null if this file is the root of a file system.

Throws:

FileSystemException - On error finding the file's parent.

getFileSystem

public FileSystem getFileSystem()

Returns the file system that contains this file.

Returns:

The file system.

getChildren

public FileObject[] getChildren()
                         throws FileSystemException

Lists the children of this file.

Returns:

An array containing the children of this file. The array is unordered. If the file does not have any children, a zero-length array is returned. This method never returns null.

Throws:

FileSystemException - If this file does not exist, or is not a folder, or on error listing this file's children.

getChild

public FileObject getChild(String name)
                    throws FileSystemException

Returns a child of this file. Note that this method returns null when the child does not exist. This differs from resolveFile( String, NameScope) which never returns null.

Parameters:

name - The name of the child.

Returns:

The child, or null if there is no such child.

Throws:

FileSystemException - If this file does not exist, or is not a folder, or on error determining this file's children.

resolveFile

public FileObject resolveFile(String name,
                              NameScope scope)
                       throws FileSystemException

Finds a file, relative to this file. Refer to NameScope for a description of how names are resolved in the different scopes.

Parameters:

name - The name to resolve.

Returns:

The file.

Throws:

FileSystemException - On error parsing the path, or on error finding the file.

resolveFile

public FileObject resolveFile(String path)
                       throws FileSystemException

Finds a file, relative to this file. Equivalent to calling resolveFile( path, NameScope.FILE_SYSTEM ).

Parameters:

path - The path of the file to locate. Can either be a relative path or an absolute path.

Returns:

The file.

Throws:

FileSystemException - On error parsing the path, or on error finding the file.

findFiles

public FileObject[] findFiles(FileSelector selector)
                       throws FileSystemException

Finds the set of matching descendents of this file, in depthwise order.

Parameters:

selector - The selector to use to select matching files.

Returns:

The matching files. The files are returned in depthwise order (that is, a child appears in the list before its parent).

Throws:

FileSystemException

findFiles

public void findFiles(FileSelector selector,
                      boolean depthwise,
                      List selected)
               throws FileSystemException

Finds the set of matching descendents of this file.

Parameters:

selector - the selector used to determine if the file should be selected

depthwise - controls the ordering in the list. e.g. deepest first

selected - container for selected files. list needs not to be empty.

Throws:

FileSystemException

delete

public boolean delete()
               throws FileSystemException

Deletes this file. Does nothing if this file does not exist of if it is a folder that has children. Does not delete any descendents of this file, use delete(FileSelector) for that.

Returns:

true if this object has been deleted

Throws:

FileSystemException - If this file is a non-empty folder, or if this file is read-only, or on error deleteing this file.

delete

public int delete(FileSelector selector)
           throws FileSystemException

Deletes all descendents of this file that match a selector. Does nothing if this file does not exist.

This method is not transactional. If it fails and throws an exception, this file will potentially only be partially deleted.

Parameters:

selector - The selector to use to select which files to delete.

Returns:

the number of deleted objects

Throws:

FileSystemException - If this file or one of its descendents is read-only, or on error deleting this file or one of its descendents.

createFolder

public void createFolder()
                  throws FileSystemException

Creates this folder, if it does not exist. Also creates any ancestor folders which do not exist. This method does nothing if the folder already exists.

Throws:

FileSystemException - If the folder already exists with the wrong type, or the parent folder is read-only, or on error creating this folder or one of its ancestors.

createFile

public void createFile()
                throws FileSystemException

Creates this file, if it does not exist. Also creates any ancestor folders which do not exist. This method does nothing if the file already exists and is a file.

Throws:

FileSystemException - If the file already exists with the wrong type, or the parent folder is read-only, or on error creating this file or one of its ancestors.

copyFrom

public void copyFrom(FileObject srcFile,
                     FileSelector selector)
              throws FileSystemException

Copies another file, and all its descendents, to this file.

If this file does not exist, it is created. Its parent folder is also created, if necessary. If this file does exist, it is deleted first.

This method is not transactional. If it fails and throws an exception, this file will potentially only be partially copied.

Parameters:

srcFile - The source file to copy.

selector - The selector to use to select which files to copy.

Throws:

FileSystemException - If this file is read-only, or if the source file does not exist, or on error copying the file.

moveTo

public void moveTo(FileObject destFile)
            throws FileSystemException

Move this file.

If the destFile exists, it is deleted first

Parameters:

destFile - the New filename.

Throws:

FileSystemException - If this file is read-only, or if the source file does not exist, or on error copying the file.

canRenameTo

public boolean canRenameTo(FileObject newfile)

Queries the file if it is possible to rename it to newfile.

Parameters:

newfile - the new file(-name)

Returns:

true it this is the case

getContent

public FileContent getContent()
                       throws FileSystemException

Returns this file's content. The FileContent returned by this method can be used to read and write the content of the file.

This method can be called if the file does not exist, and the returned FileContent can be used to create the file by writing its content.

Returns:

This file's content.

Throws:

FileSystemException - On error getting this file's content.

close

public void close()
           throws FileSystemException

Closes this file, and its content. This method is a hint to the implementation that it can release any resources associated with the file.

The file object can continue to be used after this method is called.

Throws:

FileSystemException - On error closing the file.

See Also:

FileContent.close()

refresh

public void refresh()
             throws FileSystemException

This will prepare the fileObject to get resynchronized with the underlaying filesystem if required

Throws:

FileSystemException

isAttached

public boolean isAttached()

check if the fileObject is attaced

isContentOpen

public boolean isContentOpen()

check if someone reads/write to this file

getFileOperations

public FileOperations getFileOperations()
                                 throws FileSystemException

Returns:

FileOperations interface that provides access to the operations API.

Throws:

FileSystemException