com.purpletech.io
Class CachedFS

java.lang.Object
  |
  +--com.purpletech.io.CachedFS

public class CachedFS

extends java.lang.Object

Cached File System: sits on top of a file system, loads files from disk and stores them in memory. Refreshes them if they've changed. Uses com.purpletech.util.Cache (which means that accessing an item resets its timeout clock).

Allows a filter (Loader) that processes files immediately after they're loaded, turning them into interesting objects (like byte[]s or XML documents). By default, the files are returned as String objects (assuming they're text files), but that can easily change by calling setLoader(new CachedFS.BinaryLoader()) which returns them as byte[]s. You can also create your own Loader by implementing the CachedFS.Loader interface. You can also register different loaders for different file extensions (like .gif).

Nested Class Summary

static class	CachedFS.BinaryLoader
static interface	CachedFS.Loader Callback that processes a file, turning it into an object, as it's loaded.
static interface	CachedFS.Tester Callback that provides an extra check as to whether a file needs to be reloaded.
static class	CachedFS.TextLoader

Field Summary

protected Cache	cache
static boolean	verbose

Constructor Summary

CachedFS()
JavaBean initializer -- must call setRoot immediately

CachedFS(java.io.File root)

CachedFS(java.lang.String root)

Method Summary

void	delete(java.lang.String path)
long	getCreated(java.lang.String path) use JNI to find out the date the file was created -- not yet implemented
java.lang.Object	getFile(java.lang.String path) Load a file, or use the cached version if the file hasn't changed.
java.util.List	getFilenames(java.lang.String path) Get a list of all files in a given directory.
long	getLastModified(java.lang.String path)
long	getModified(java.lang.String path)
java.util.List	list(java.lang.String path) convenience wrapper
protected java.lang.Object	loadFile(java.lang.String path, java.io.File f)
static void	main(java.lang.String[] args)
protected java.io.File	makeFileObject(java.lang.String path)
void	move(java.lang.String path, java.lang.String topath)
void	setCacheTimeout(long x)
void	setLoader(CachedFS.Loader loader) register a default loader.
void	setLoader(java.lang.String ext, CachedFS.Loader loader) register a loader for a given extension.
void	setRoot(java.io.File root)
void	setRoot(java.lang.String root)
void	setTester(CachedFS.Tester t)
java.io.OutputStream	writeFile(java.lang.String path) Make sure you close the OutputStream! Otherwise, the lock will remain.

Methods inherited from class java.lang.Object

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

Field Detail

verbose

public static boolean verbose

cache

protected Cache cache

Constructor Detail

CachedFS

public CachedFS()

JavaBean initializer -- must call setRoot immediately

CachedFS

public CachedFS(java.io.File root)

Parameters:

root - the root directory

CachedFS

public CachedFS(java.lang.String root)

Parameters:

root - the root directory

Method Detail

setCacheTimeout

public void setCacheTimeout(long x)

setRoot

public void setRoot(java.lang.String root)

Parameters:

root - the root directory

setRoot

public void setRoot(java.io.File root)

Parameters:

root - the root directory

setLoader

public void setLoader(CachedFS.Loader loader)

register a default loader. E.g. fs.setLoader(new CachedFS.TextLoader())

setLoader

public void setLoader(java.lang.String ext,
                      CachedFS.Loader loader)

register a loader for a given extension. E.g. fs.addLoader("gif", new CachedFS.BinaryLoader())

Parameters:

ext - the file extension to process

loader - the Loader to process that type of file

setTester

public void setTester(CachedFS.Tester t)

makeFileObject

protected java.io.File makeFileObject(java.lang.String path)

getFile

public java.lang.Object getFile(java.lang.String path)
                         throws java.io.IOException

Load a file, or use the cached version if the file hasn't changed.

Parameters:

path - path to file, relative to fs root

java.io.IOException

loadFile

protected java.lang.Object loadFile(java.lang.String path,
                                    java.io.File f)
                             throws java.io.IOException

java.io.IOException

writeFile

public java.io.OutputStream writeFile(java.lang.String path)
                               throws java.io.IOException

Make sure you close the OutputStream! Otherwise, the lock will remain. (Use finally { out.close(); })

java.io.IOException

getFilenames

public java.util.List getFilenames(java.lang.String path)
                            throws java.io.IOException

Get a list of all files in a given directory. Note that it's not cached, since we have no easy way to tell if the contents have changed.

Parameters:

path - directory to list

Returns:

list of all file names in directory. Directories end in '/'

java.io.IOException

list

public java.util.List list(java.lang.String path)
                    throws java.io.IOException

convenience wrapper

java.io.IOException

delete

public void delete(java.lang.String path)
            throws java.io.IOException

java.io.IOException

move

public void move(java.lang.String path,
                 java.lang.String topath)
          throws java.io.IOException

java.io.IOException

getLastModified

public long getLastModified(java.lang.String path)

getModified

public long getModified(java.lang.String path)

getCreated

public long getCreated(java.lang.String path)

use JNI to find out the date the file was created -- not yet implemented

main

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

java.io.IOException