Apache VFS (7): File Manager File Parsing Method

Navigation of this series of articles

Apache VFS (1): Basic Introduction

Apache VFS (2): file monitoring and monitoring

Apache VFS (3): file filter and Selector

Apache VFS (4): Events

Apache VFS (5): use it!

Apache VFS (6): several important conceptual Interfaces

Apache VFS (7): File Manager File Parsing Method

In general, when we use Apache VFS, the File Manager obtained directly from the VFS object isStandardFileSystemManager

, Standardfilesystemmanager is inherited from defaultfilesystemmanager. The parsing FileDefaultFileSystemManager

.

In most cases, you will provide a URI to locate your file system. For example:Ftp: // yourftp/rootdir or http: // yourweb/rootdi

R or file: // C:/rootdir

And pass the string as a parameter to standardfilesystemmanger.ResolveFile Method

Parses the URI and returns a fileobject object. Let's take a look at this method:

This method has five reload methods that accept different parameters, but the core method has only one:

/**

* Resolves a URI, realtive to a base file with specified filesystem

* Configuration

*/

Public FileObject resolveFile (final FileObject baseFile, final String uri,

Final FileSystemOptions fileSystemOptions)

Throws FileSystemException

{

Final FileObject realBaseFile;

If (baseFile! = Null & VFS. isUriStyle ()

& BaseFile. getName (). getType () = FileType. FILE)

{

RealBaseFile = baseFile. getParent ();

}

Else

{

Realbasefile = basefile;

}

// Todo: Use resolvename and use this name to resolve the fileobject

Uriparser. checkuriencoding (URI );

If (uri = NULL)

{

Throw new illegalargumentexception ();

}

// Extract the Scheme

Final string scheme = uriparser. extractscheme (URI );

If (scheme! = NULL)

{

// An absolute URI-locate the provider

Final fileprovider provider = (fileprovider) providers. Get (scheme );

If (provider! = NULL)

{

Return provider. findfile (realbasefile, Uri, filesystemoptions );

}

// Otherwise, assume a local file

}

// Handle absolute file names

If (localfileprovider! = NULL

& Localfileprovider. isabsolutelocalname (URI ))

{

Return localfileprovider. findlocalfile (URI );

}

If (scheme! = NULL)

{

// An unknown scheme-hand it to the default provider

If (defaultprovider = NULL)

{

Throw new FileSystemException ("vfs. impl/unknown-scheme.error ",

New Object []

{Scheme, uri });

}

Return defaultProvider. findFile (realBaseFile, uri,

FileSystemOptions );

}

// Assume a relative name-use the supplied base file

If (realBaseFile = null)

{

Throw new FileSystemException ("vfs. impl/find-rel-file.error", uri );

}

Return realBaseFile. resolveFile (uri );

}

 

 

Source: http://alartin.javaeye.com/blog/92436