edu.nps.util

Class FileTreeUpdater

java.lang.Object

edu.nps.util.FileTreeUpdater

public class FileTreeUpdater
extends Object

This class will update (by time-of-modification) a local file tree with a remote, mirrored file tree. More precisely, it will mirror remote files on the local machine, and replace the local ones only if they are older than the remote. It uses the Jakarta VFS (Virtual File System) project. (See http://jakarta.apache.org/commons/vfs/.) This code (eventually) supports, by use of appropriate server URLs, remote file systems accessed by FTP, SFTP, HTTP, HTTPS, ZIP, JAR, TAR, WebDAV, and a few others. At the time this code was written, HTTP and HTTPS did not reliably support our use to map a complete file tree. SFTP did, and it is presumed that FTP would too, although that was not tested. See http://jakarta.apache.org/commons/vfs/filesystems.html for a description of the file systems (to be) supported. The normal usage of this class is:

   FileTreeUpdater ftu = null;
   try {
     FileTreeUpdater ftu = new FileTreeUpdater("remote URL","local path");
     List lis = ftu.scan();    // find changed files
     if(lis.size() >> 0) {      // no changes if empty list returned
       ftu.downloadUpdates();  // download changed files
       ftu.copyUpdates();      // put changed files into place
     }
   }
   catch (IOException e) {
     e.printStackTrace();
   }
 

A URL example for the SFTP protocol is:

   sftp://[ username[: password]@] hostname[: port][ absolute-path]
 

Example:

   sftp://myusername:mypassword@somehost/pub/downloads/somefile.tgz
 

This url is maintained in file

   ///AuvWorkbench/configuration/c_app.xml
 

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	FileTreeUpdater.OpDone
static interface	FileTreeUpdater.StatusLineOut Used to receive status updates from a FileTreeUpdater instance.

Field Summary

Fields

Modifier and Type	Field and Description
protected org.apache.commons.vfs.FileSystemManager	fsManager
protected String	localPath
protected org.apache.commons.vfs.FileObject	root
protected File	tmpDir
protected String	url

Constructor Summary

Constructors

Constructor and Description
FileTreeUpdater(String _url, String _localPath) Construct this class and connect to remote machine.
FileTreeUpdater(String _url, String _localPath, FileTreeUpdater.StatusLineOut _slo) Constructor with passed object to receive status and error messages

Method Summary

Modifier and Type	Method and Description
void	_copyF(File src, File dest)
void	addExcludedName(String name)
void	asyncCopyUpdates(FileTreeUpdater.OpDone od, List<String> filteredList)
void	asyncDownloadUpdates(FileTreeUpdater.OpDone od, List<String> filteredList)
void	asyncScan(FileTreeUpdater.OpDone od)
void	cancel() For multi-threaded uses of this class, this will signal the processing loops to stop.
void	clearDownloadCache()
void	close()
void	copyUpdates(List<String> filteredList) Move the downloaded files into place, overwriting existing files.
void	downloadUpdates(List<String> filteredList) Download the changed files into a temporary directory in preparation for overwrite of local tree.
File	getDownloadCacheRoot()
int	getFileCount()
int	getScanListCount()
List<String>	scan() Perform a scan of the remote machine.

Methods inherited from class java.lang.Object

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

Field Detail

url

protected String url

localPath

protected String localPath

tmpDir

protected File tmpDir

fsManager

protected org.apache.commons.vfs.FileSystemManager fsManager

root

protected org.apache.commons.vfs.FileObject root

Constructor Detail

FileTreeUpdater

public FileTreeUpdater(String _url,
                       String _localPath)
                throws Exception

Construct this class and connect to remote machine. Throw exception if error.

Parameters:

_url - URL string with scheme and user:password if required

_localPath - local path to update

Throws:

Exception - if network error

FileTreeUpdater

public FileTreeUpdater(String _url,
                       String _localPath,
                       FileTreeUpdater.StatusLineOut _slo)
                throws Exception

Constructor with passed object to receive status and error messages

Parameters:

_url - see FileTreeUpdater(String,String).

_localPath - see FileTreeUpdater(String,String).

_slo - see StatusLineOut interface.

Throws:

Exception - see FileTreeUpdater(String,String).

Method Detail

getFileCount

public int getFileCount()

Returns:

number of files counted so far

cancel

public void cancel()

For multi-threaded uses of this class, this will signal the processing loops to stop.

addExcludedName

public void addExcludedName(String name)

getScanListCount

public int getScanListCount()

Returns:

number of files scanned

scan

public List<String> scan()
                  throws IOException

Perform a scan of the remote machine. Build a list of the files which are newer than the local version of the same name or don't exist locally.

Returns:

said list

Throws:

IOException

asyncScan

public void asyncScan(FileTreeUpdater.OpDone od)

downloadUpdates

public void downloadUpdates(List<String> filteredList)
                     throws IOException

Download the changed files into a temporary directory in preparation for overwrite of local tree. If an exception occurs when handling an individual file, the exception is trapped internally and a message is written on System.error, but the download iteration continues. The last exception seen is the one thrown by this method to indicate an error.

Parameters:

filteredList -

Throws:

IOException - last error seen

asyncDownloadUpdates

public void asyncDownloadUpdates(FileTreeUpdater.OpDone od,
                                 List<String> filteredList)

copyUpdates

public void copyUpdates(List<String> filteredList)
                 throws IOException

Move the downloaded files into place, overwriting existing files. Similar to the exception handling in downloadUpdates(java.util.List<java.lang.String>).

Parameters:

filteredList -

Throws:

IOException - last error seen

clearDownloadCache

public void clearDownloadCache()

getDownloadCacheRoot

public File getDownloadCacheRoot()

asyncCopyUpdates

public void asyncCopyUpdates(FileTreeUpdater.OpDone od,
                             List<String> filteredList)

close

public void close()

_copyF

public void _copyF(File src,
                   File dest)
            throws IOException

Throws:

IOException