directoryresource.java

很棒的web服务器源代码

// DirectoryResource.java
// $Id: DirectoryResource.java,v 1.24 2003/06/06 14:23:14 ylafon Exp $
// (c) COPYRIGHT MIT and INRIA, 1996.
// Please first read the full copyright statement in file COPYRIGHT.html

package org.w3c.tools.resources ;

import java.util.Enumeration;
import java.util.Hashtable;

import java.io.File;
import java.io.PrintStream;
import java.io.RandomAccessFile;

import org.w3c.tools.resources.indexer.IndexerModule;
import org.w3c.tools.resources.indexer.ResourceIndexer;

import org.w3c.tools.resources.event.StructureChangedEvent;

/**
 * A simple, and reasonably efficient directory resource.
 */
public class DirectoryResource extends ContainerResource {
    /**
     * Attribute index - The index for our directory attribute.
     */
    protected static int ATTR_DIRECTORY = -1 ;
    /**
     * Attribute index - The last time we physically visited the directory.
     */
    protected static int ATTR_DIRSTAMP = -1 ;
    /**
     * Attribute index - The indexer to use for that directory, if any.
     */
    protected static int ATTR_INDEXER = -1;
    /**
     * Attribute index - The index of wether we are extensible.
     */
    protected static int ATTR_EXTENSIBLE = -1 ;
    /**
     * Attribute index - The index of wether we can be shrinked.
     */
    protected static int ATTR_SHRINKABLE = -1 ;

    static String di = "directory".intern();

    static {
	Attribute a   = null ;
	Class     cls = null ;
	// Get a pointer to our class.
	try {
	    cls = Class.forName("org.w3c.tools.resources.DirectoryResource") ;
	} catch (Exception ex) {
	    ex.printStackTrace() ;
	    System.exit(1) ;
	}
	// The directory attribute.
	a = new FileAttribute("directory"
			      , null
			      , Attribute.COMPUTED|Attribute.DONTSAVE);
	ATTR_DIRECTORY = AttributeRegistry.registerAttribute(cls, a) ;
	// The last time we visited the directory
	a = new DateAttribute("dirstamp"
			      , null
			      , Attribute.COMPUTED) ;
	ATTR_DIRSTAMP = AttributeRegistry.registerAttribute(cls, a) ;
	// Our indexer name (optional).
	a = new StringAttribute("indexer"
				, null
				, Attribute.EDITABLE) ;
	ATTR_INDEXER = AttributeRegistry.registerAttribute(cls, a) ;
	// Are we extensible (can we create resources on the fly):
	a = new BooleanAttribute("extensible"
				 , Boolean.TRUE
				 , Attribute.EDITABLE) ;
	ATTR_EXTENSIBLE = AttributeRegistry.registerAttribute(cls, a) ;
	// Are we shrinkable (can we delete resources on the fly):
	a = new BooleanAttribute("shrinkable"
				 , Boolean.TRUE
				 , Attribute.EDITABLE) ;
	ATTR_SHRINKABLE = AttributeRegistry.registerAttribute(cls, a) ;
    }

    /**
     * Get the indexer out of the given context.
     * @return A ResourceIndexer instance, guaranteeed not to be <strong>
     * null</strong>.
     */
    protected ResourceReference getIndexer(ResourceContext c) {
	IndexerModule   m = (IndexerModule) c.getModule(IndexerModule.NAME);
	ResourceReference rr = m.getIndexer(c);
	return rr;
    }

    public void setValue(int idx, Object value) {
	super.setValue(idx, value);
	if ( idx == ATTR_INDEXER ) {
	    String indexer = getString(ATTR_INDEXER, null);	    
	    if ( indexer != null ) {
		ResourceContext c = null;
		IndexerModule   m = null;
		c = getContext();
		m = (IndexerModule) c.getModule(IndexerModule.NAME);
		m.registerIndexer(c, indexer);
	    }
	}
    }

    /**
     * Get the physical directory exported by this resource.
     * @return A non-null File object giving the directory of this resource.
     */

    public File getDirectory() {
	return (File) getValue(ATTR_DIRECTORY, null) ;
    }

    /**
     * Get the physical directory exported by this resource.
     * @return A non-null File object giving the directory of this resource.
     */

    public File unsafeGetDirectory() {
	return (File) unsafeGetValue(ATTR_DIRECTORY, null) ;
    }

    /**
     * Get the absolute time at which we examined the physicall directory.
     * @return The date (as a long number of ms since Java epoch), or
     * <strong>-1</strong> if we never examined it before.
     */

    public long getDirStamp() {
	return getLong(ATTR_DIRSTAMP, -1) ;
    }

    /**
     * Get the extensible flag value.
     * A DirectoryResource is extensible, if it is allowed to create new
     * resources out of the file system knowledge on the fly.
     * <p>Setting this flag might slow down the server. It unfortunatelly
     * defaults to <strong>true</strong> until I have a decent admin
     * program.
     * @return A boolean <strong>true</strong> if the directory is
     *    extensible.
     */

    public boolean getExtensibleFlag() {
	return getBoolean(ATTR_EXTENSIBLE, true) ;
    }

    /**
     * Get the extensible flag value.
     * A DirectoryResource is extensible, if it is allowed to create new
     * resources out of the file system knowledge on the fly.
     * <p>Setting this flag might slow down the server. It unfortunatelly
     * defaults to <strong>true</strong> until I have a decent admin
     * program.
     * @return A boolean <strong>true</strong> if the directory is
     *    extensible.
     */

    public boolean getShrinkableFlag() {
	return getBoolean(ATTR_SHRINKABLE, true) ;
    }

    /**
     * Get the extensible flag value.
     * A DirectoryResource is extensible, if it is allowed to create new
     * resources out of the file system knowledge on the fly.
     * <p>Setting this flag might slow down the server. It unfortunatelly
     * defaults to <strong>true</strong> until I have a decent admin
     * program.
     * @return A boolean <strong>true</strong> if the directory is
     *    extensible.
     */

    public boolean unsafeGetShrinkableFlag() {
	Object value = unsafeGetValue(ATTR_SHRINKABLE, null) ;
	if (value == null) {
	    return true;
	} else if ( value instanceof Boolean ) {
	    return ((Boolean) value).booleanValue() ;
	} else {
	    throw new IllegalAttributeAccess(this
					     , attributes[ATTR_SHRINKABLE]
					     , "getBoolean") ;
	}
    }

    /**
     * A resource is about to be removed
     * This handles the <code>RESOURCE_REMOVED</code> kind of events.
     * @param evt The event describing the change.
     */
    public void resourceRemoved(StructureChangedEvent evt) {
	super.resourceRemoved(evt);
	if (! isUnloaded())
	    markModified();
    }

    /**
     * Create a DirectoryResource and the physical directory too.
     * @param name the name of the resource.
     * @return A ResourceReference instance.
     */
    public ResourceReference createDirectoryResource(String name) {
	// Create an empty file:
	File    file          = new File(getDirectory(), name) ;
	boolean created       = false ;
	boolean exists_before = false ;

	try {
	    if (file.exists()) {
		if (! file.isDirectory())
		    created = false;
		else
		    exists_before = true;
	    } else {
		file.mkdir();
		created = true;
	    }
	} catch (Exception ex) {
	    created = false;
	}

	if (! created)
	    return null;

	ResourceReference rr = createDefaultResource(name);
	if (rr == null) {
	    if (!exists_before)
		file.delete();
	    return null;
	}

	try {
	    Resource r = rr.lock();
	    if (! (r instanceof DirectoryResource)) {
		try {
		    r.delete();
		} catch (MultipleLockException ex) {
		    //OUCH!
		    //manual delete
		}
		if (!exists_before)
		    file.delete();
		return null;
	    }
	} catch (InvalidResourceException ex) {
	    if (!exists_before)
		file.delete();
	    return null;
	} finally {
	    rr.unlock();
	}
	return rr;
    }

    /**
     * Create a Resource and the physical file too.
     * @param name the name of the resource.
     * @return A ResourceReference instance.
     */
    public ResourceReference createResource(String name) {
	return createResource(name, null);
    }

    /**
     * Create a Resource and the physical file too.
     * @param name the name of the resource.
     * @param req the protocol request.
     * @return A ResourceReference instance.
     */
    public ResourceReference createResource(String name, 
					    RequestInterface req) 
    {
	// Create an empty file:
	File    file    = new File(getDirectory(), name) ;
	boolean created = false ;

	if ( ! file.exists() ) {
	    try {
		(new RandomAccessFile(file, "rw")).close() ;
		created = true ;
	    } catch (Exception ex) {
		created = false ;
	    }
	}
	if (! created) 
	    return null;

	ResourceReference rr = createDefaultResource(name, req);
	//if (rr == null)
	file.delete();
	return rr;
    }

    /**
     * Index a Resource. Call the indexer.
     * @param name The name of the resource to index.
     * @param defs The defaults attributes.
     * @return A resource instance.
     * @see org.w3c.tools.resources.indexer.SampleResourceIndexer
     */
    private Resource index(String name, Hashtable defs) {
	return index(name, defs, null);
    }

    /**
     * Index a Resource. Call the indexer.
     * @param name The name of the resource to index.
     * @param defs The defaults attributes.
     * @param req The protocol request.
     * @return A resource instance.
     * @see org.w3c.tools.resources.indexer.SampleResourceIndexer
     */
    protected Resource index(String name, 
			     Hashtable defs, 
			     RequestInterface req) 
    {
	// Prepare a set of default parameters for the resource:
	defs.put(id, name);
	updateDefaultChildAttributes(defs);
	ResourceContext context = getContext();
	// Try to get the indexer to create the resource:
	Resource    resource = null;
	ResourceReference rr_indexer  = null;
	ResourceReference rr_lastidx  = null;
	while ( context != null ) {
	    // Lookup for next indexer in hierarchy:
	    do {
		rr_indexer = getIndexer(context);
		context = context.getParent();
	    } while ((rr_indexer == rr_lastidx) && (context != null));
	    // Is this a useful indexer ?
	    if ((rr_lastidx = rr_indexer) != null ) {
		try {
		    ResourceIndexer indexer = 
			(ResourceIndexer)rr_indexer.lock();
		    resource = indexer.createResource(this,
						      req,
						      getDirectory(),
						      name,
						      defs) ;
		    if ( resource != null )