/*
* Copyright 1999-2004 The Apache Software Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.cocoon.components.modules.input;
import org.apache.avalon.framework.component.ComponentException;
import org.apache.avalon.framework.component.ComponentManager;
import org.apache.avalon.framework.component.Composable;
import org.apache.avalon.framework.configuration.Configuration;
import org.apache.avalon.framework.configuration.ConfigurationException;
import org.apache.avalon.framework.thread.ThreadSafe;
import org.apache.excalibur.source.Source;
import org.apache.excalibur.source.SourceResolver;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.TreeSet;
import java.util.Vector;
/**
* Loacte a resource in a resource tree. Any attribute name is interpreted as a
* URI with the last part being the resource name unless it ends with a slash.
* The URI is checked if the resource exists and the URI is returned. If the
* resource does not exist, the URI is shortened until the resource name is found
* and the new URI is returned. If no resource with the given name exists, null
* is returned.
*
* <p>A use case is to locate the closest menu file or when moving a site from
* a filesystem path == URL system from a httpd to Cocoon and provide similar
* functions to .htaccess files.</p>
*
* <p>Example: for context:/some/path/to/a/file.xml the following URIs
* are tested: context:/some/path/to/a/file.xml, context:/some/path/to/file.xml,
* context:/some/path/file.xml, context:/some/file.xml, and context:/file.xml.
* For the attribute name context:/some/path/foo/ tests context:/some/path/foo/,
* context:/some/path/, context:/some/, and context:/ are tested.</p>
*
* <p>The getAttribute() method will return the URI for the first match while
* getAttributeValues() will return an array of all existing paths.
* getAttributeNames() will return an Iterator to an empty collection.</p>
*
* @author <a href="mailto:haul@apache.org">Christian Haul</a>
* @version CVS $Id: LocateResource.java,v 1.3 2004/03/05 13:02:48 bdelacretaz Exp $
*/
public class LocateResource extends AbstractInputModule implements Composable, ThreadSafe {
protected static Collection col = null;
static {
col = new TreeSet();
}
protected ComponentManager manager = null;
/**
* Calculate the minimal length of the URL, that is the position
* of the first ":" if a protocol is provided or otherwise 0.
* @param name
* @return minimal length
*/
protected int calculateMinLen(String name) {
int minLen = name.indexOf(':');
minLen = (minLen == -1 ? 0 : minLen);
return minLen;
}
/**
* Remove one path element from the URL unless minimum length has
* been reached.
*
* @param urlstring
* @param minLen
* @return shortened URI
*/
protected String shortenURI(String urlstring, int minLen) {
int idx = urlstring.lastIndexOf('/');
idx = (idx <= minLen + 1) ? minLen : idx;
urlstring = urlstring.substring(0, idx);
return urlstring;
}
/**
* if the url does not end with a "/", keep the last part in
* order to add it later again after traversing up
*/
protected String extractFilename(String urlstring) {
String filename = "";
if (!urlstring.endsWith("/")) {
int idx = urlstring.lastIndexOf('/');
filename = urlstring.substring(idx);
}
return filename;
}
/**
* Locate a resource with the given URL consisting of urlstring + filename.
* The filename is appended each time the path is shortened. Returns the first
* existing occurance.
*
* @param urlstring
* @param filename
* @param minLen
* @return urlstring if resource was found, <code>null</code> otherwise
*/
protected String locateResource(String urlstring, String filename, int minLen) {
String sourcename = null;
Source src = null;
SourceResolver resolver = null;
boolean found = false;
try {
resolver =
(SourceResolver) this.manager.lookup(
org.apache.excalibur.source.SourceResolver.ROLE);
while (!found && urlstring.length() > minLen) {
sourcename = urlstring + filename;
try {
src = resolver.resolveURI(sourcename);
if (src.exists())
found = true;
} catch (Exception e) {
if (this.getLogger().isWarnEnabled())
this.getLogger().warn("Exception resolving URL " + sourcename, e);
} finally {
resolver.release(src);
}
if (!found) {
urlstring = shortenURI(urlstring, minLen);
}
}
} catch (ComponentException e1) {
if (this.getLogger().isErrorEnabled())
this.getLogger().error("Exception obtaining source resolver ", e1);
} finally {
if (resolver != null) {
this.manager.release(resolver);
}
}
return (found ? urlstring : null);
}
/**
* Set the current <code>ComponentManager</code> instance used by this
* <code>Composable</code>.
*/
public void compose(ComponentManager manager) throws ComponentException {
this.manager = manager;
}
/* (non-Javadoc)
* @see org.apache.cocoon.components.modules.input.InputModule#getAttribute(java.lang.String, org.apache.avalon.framework.configuration.Configuration, java.util.Map)
*/
public Object getAttribute(String name, Configuration modeConf, Map objectModel)
throws ConfigurationException {
String urlstring = name;
String filename = extractFilename(urlstring);
int minLen = calculateMinLen(name);
if (filename != "") {
urlstring = shortenURI(urlstring, minLen);
}
String result = locateResource(urlstring, filename, minLen);
result = (result == null? result : result + filename);
if (this.getLogger().isDebugEnabled())
this.getLogger().debug(
"located " + name + " @ " + result);
return result;
}
/* (non-Javadoc)
* @see org.apache.cocoon.components.modules.input.InputModule#getAttributeNames(org.apache.avalon.framework.configuration.Configuration, java.util.Map)
*/
public Iterator getAttributeNames(Configuration modeConf, Map objectModel)
throws ConfigurationException {
// return an iterator to an empty collection
return LocateResource.col.iterator();
}
/* (non-Javadoc)
* @see org.apache.cocoon.components.modules.input.InputModule#getAttributeValues(java.lang.String, org.apache.avalon.framework.configuration.Configuration, java.util.Map)
*/
public Object[] getAttributeValues(String name, Configuration modeConf, Map objectModel)
throws ConfigurationException {
Vector uris = null;
String urlstring = name;
String filename = extractFilename(urlstring);
int minLen = calculateMinLen(name);
if (filename != "") {
urlstring = shortenURI(urlstring, minLen);
}
while (urlstring != null && urlstring.length() > minLen) {
urlstring = this.locateResource(urlstring, filename, minLen);
if (urlstring != null) {
if (uris == null)
uris = new Vector();
if (this.getLogger().isDebugEnabled())
this.getLogger().debug("-> located " + name + " @ " + urlstring + filename);
uris.add(urlstring + filename);
urlstring = shortenURI(urlstring, minLen);
}
}
return (uris == null ? null : uris.toArray());
}
}