/*
* 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.source.impl;
import java.io.InputStream;
import java.io.IOException;
import java.io.ByteArrayInputStream;
import java.net.MalformedURLException;
import java.util.Map;
import org.apache.avalon.framework.configuration.ConfigurationException;
import org.apache.avalon.framework.logger.Logger;
import org.apache.avalon.framework.service.ServiceException;
import org.apache.avalon.framework.service.ServiceManager;
import org.apache.avalon.framework.service.ServiceSelector;
import org.apache.excalibur.source.SourceException;
import org.apache.excalibur.source.impl.AbstractSource;
import org.apache.cocoon.components.modules.input.InputModule;
import org.apache.commons.jxpath.JXPathContext;
/**
* A <code>Source</code> that takes its content from a
* module.
* <p>The URI syntax is
* "module:<input-module>:<attribute-name>[#XPath]",
* where :
* <ul>
* <li>an input-module name is used for finding an input-module for reading data from</li>,
* <li>"attribute-name" is the name of the attribute found in the module</li>,
* <li>"XPath" is an XPath that is aplied on the object in the
* attribute, by using JXPath.</li>
* </ul>
* </p>
*
* @author <a href="mailto:danielf@nada.kth.se">Daniel Fagerstom</a>
*/
public class ModuleSource
extends AbstractSource {
private final static String SCHEME = "module";
private String attributeType;
private String attributeName;
private String xPath;
private ServiceManager manager;
private Map objectModel;
private Logger logger;
/**
* Create a module source from a 'module:' uri and a the object model.
* <p>The uri is of the form "module:attribute-type:attribute-name#xpath</p>
*/
public ModuleSource( Map objectModel, String uri,
ServiceManager manager, Logger logger )
throws MalformedURLException {
this.objectModel = objectModel;
this.manager = manager;
this.logger = logger;
setSystemId( uri );
// Scheme
int start = 0;
int end = uri.indexOf( ':' );
if ( end == -1 )
throw new MalformedURLException("Malformed uri for module source (cannot find scheme) : " + uri);
String scheme = uri.substring( start, end );
if ( !SCHEME.equals( scheme ) )
throw new MalformedURLException("Malformed uri for a module source : " + uri);
setScheme( scheme );
// Attribute type
start = end + 1;
end = uri.indexOf( ':', start );
if ( end == -1 ) {
throw new MalformedURLException("Malformed uri for module source (cannot find attribute type) : " + uri);
}
this.attributeType = uri.substring( start, end );
// Attribute name
start = end + 1;
end = uri.indexOf( '#', start );
if ( end == -1 )
end = uri.length();
if ( end == start )
throw new MalformedURLException("Malformed uri for module source (cannot find attribute name) : " + uri);
this.attributeName = uri.substring( start, end );
// xpath
start = end + 1;
this.xPath = start < uri.length() ? uri.substring( start ) : "";
}
/**
* Return an <code>InputStream</code> object to read from the source.
*
* @throws IOException if I/O error occured.
*/
public InputStream getInputStream() throws IOException, SourceException {
if ( this.logger.isDebugEnabled() ) {
this.logger.debug( "Getting InputStream for " + getURI() );
}
Object obj = getInputAttribute( this.attributeType, this.attributeName );
if ( obj == null )
throw new SourceException( " The attribute: " + this.attributeName +
" is empty" );
if ( !(this.xPath.length() == 0 || this.xPath.equals( "/" )) ) {
JXPathContext context = JXPathContext.newContext( obj );
obj = context.getValue( this.xPath );
if ( obj == null )
throw new SourceException( "the xpath: " + this.xPath +
" applied on the attribute: " +
this.attributeName +
" returns null");
}
if ( obj instanceof InputStream ) {
return (InputStream)obj;
} else if ( obj instanceof String ) {
return new ByteArrayInputStream( ((String)obj).getBytes() );
} else {
throw new SourceException( "The object type: " + obj.getClass() +
" could not be serialized as a InputStream " + obj );
}
}
/**
* Does this source actually exist ?
*
* @return true if the resource exists.
*
*/
public boolean exists() {
boolean exists = false;
try {
exists = getInputAttribute( this.attributeType, this.attributeName ) != null;
} catch ( SourceException e ) {
exists = false;
}
return exists;
}
private Object getInputAttribute( String inputModuleName, String attributeName )
throws SourceException {
Object obj;
ServiceSelector selector = null;
InputModule inputModule = null;
try {
selector = (ServiceSelector) this.manager.lookup( InputModule.ROLE + "Selector" );
inputModule = (InputModule) selector.select( inputModuleName );
obj = inputModule.getAttribute( attributeName, null, this.objectModel );
} catch ( ServiceException e ) {
throw new SourceException( "Could not find an InputModule of the type " +
inputModuleName , e );
} catch ( ConfigurationException e ) {
throw new SourceException( "Could not find an attribute: " + attributeName +
" from the InputModule " + inputModuleName, e );
} finally {
if ( inputModule != null ) selector.release( inputModule );
this.manager.release( selector );
}
return obj;
}
}