/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 java.util.Iterator;
import java.util.Map;
import org.apache.avalon.framework.configuration.Configuration;
import org.apache.avalon.framework.configuration.ConfigurationException;
import org.apache.avalon.framework.thread.ThreadSafe;
/**
* JXPathModule allows to access properties of any object in generic
* way. JXPath provides APIs for the traversal of graphs of
* JavaBeans, DOM and other types of objects using the XPath
* syntax.
*
* <p><strong>Note:</strong> This is based on the AbstractJXPathModule
* and duplicates the code since multiple inheritance is not possible.
* Please keep both classes in sync.</p>
*
* <p>Configuration example:</p>
* <table>
* <tr>
* <td><code><lenient>false</lenient></td>
* <td>When set to true, non-existing attributes return null, when set to false,
* an exception is thrown. Default is true.</td>
* </tr>
* <tr>
* <td><code><parameter>false</parameter></td>
* <td>Attribute name to be used instead of passed attribute name.</td>
* </tr>
* <tr>
* <td><code><from-parameter>false</from-parameter></td>
* <td>Attribute name to pass to configured input module</td>
* </tr>
* <tr>
* <td><code><input-module name="request-attr"/></td>
* <td>Uses the "request-attr" input module to obtain a value and
* applies the given JXPath expression to it.</td>
* </tr>
* <tr>
* <td><code><function name="java.lang.String" prefix="str"/></td>
* <td>Imports the class "String" as extension class to the JXPathContext using
* the prefix "str". Thus "str:length(xpath)" would apply the method "length" to
* the string object obtained from the xpath expression. Please note that the class
* needs to be fully qualified.</td>
* </tr>
* <tr>
* <td><code><package name="java.util" prefix="util"/></td>
* <td>Imports all classes in the package "java.util" as extension classes to the
* JXPathContext using the prefix "util". Thus "util:Date.new()" would create a
* new java.util.Date object.</td>
* </tr>
* <tr>
* <td><code><namespace uri="uri:foo" prefix="bar"/></td>
* <td>Registers the namespace identified by URI <code>uri:foo</code>
* with the JXPathContext using the prefix <code>bar</code>. Thus
* expressions can query XML with nodes in this namespace using
* registered prefix.</td>
* </tr>
* </table>
*
* <p>In addition, it accepts the attributes "parameter" to override
* the attribute name and "from-parameter" to pass as attribute name
* to the configured input module.</p>
*
* @author <a href="mailto:kpiroumian@apache.org">Konstantin Piroumian</a>
* @author <a href="mailto:haul@apache.org">Christian Haul</a>
* @author <a href="mailto:vgritsenko@apache.org">Vadim Gritsenko</a>
* @version $Id$
*/
public class JXPathMetaModule extends AbstractMetaModule implements ThreadSafe {
/**
* Contains all globally registered extension classes and
* packages. Thus the lookup and loading of globally registered
* extensions is done only once.
*/
protected JXPathHelperConfiguration configuration;
/**
* Overrides attribute name
*/
protected String parameter = "";
public JXPathMetaModule() {
// this value has a default in the super class
super.defaultInput = "request-attr";
}
/**
* Configure component. Preprocess list of packages and functions
* to add to JXPath context later.
*
* @param config a <code>Configuration</code> value
* @exception ConfigurationException if an error occurs
*/
public void configure(Configuration config) throws ConfigurationException {
this.inputConf = config.getChild("input-module");
this.defaultInput = this.inputConf.getAttribute("name",this.defaultInput);
this.parameter = config.getChild("parameter").getValue(this.parameter);
this.configuration = JXPathHelper.setup(config);
}
public Object getAttribute(String name, Configuration modeConf, Map objectModel)
throws ConfigurationException {
Object contextObj = getContextObject(modeConf, objectModel);
if (modeConf != null) {
name = modeConf.getChild("parameter").getValue(!this.parameter.equals("") ? this.parameter : name);
}
return JXPathHelper.getAttributeValue(name, modeConf, this.configuration, contextObj);
}
public Iterator getAttributeNames(Configuration modeConf, Map objectModel)
throws ConfigurationException {
Object contextObj = getContextObject(modeConf, objectModel);
return JXPathHelper.getAttributeNames(this.configuration, contextObj);
}
public Object[] getAttributeValues(String name, Configuration modeConf, Map objectModel)
throws ConfigurationException {
Object contextObj = getContextObject(modeConf, objectModel);
if (modeConf != null) {
name = modeConf.getChild("parameter").getValue(!this.parameter.equals("") ? this.parameter : name);
}
return JXPathHelper.getAttributeValues(name, modeConf, this.configuration, contextObj);
}
/**
* Looks up object from configured InputModule.
*
* @param modeConf a <code>Configuration</code> value
* @param objectModel a <code>Map</code> value
* @return an <code>Object</code> value
*/
protected Object getContextObject(Configuration modeConf, Map objectModel)
throws ConfigurationException {
if (!this.initialized) {
lazy_initialize();
}
Configuration mConf = null;
String inputName = null;
String parameter = this.parameter;
if (modeConf != null) {
mConf = modeConf.getChild("input-module");
inputName = mConf.getAttribute("name", null);
parameter = modeConf.getChild("from-parameter").getValue(parameter);
}
if (getLogger().isDebugEnabled()) {
getLogger().debug("modeConf is " + modeConf + " this.inputConf is " + this.inputConf
+ " mConf is " + mConf + " this.input is " + this.input
+ " this.defaultInput is " + this.defaultInput
+ " inputName is " + inputName + " parameter is " + parameter);
}
Object obj = getValue(parameter, objectModel,
this.input, this.defaultInput, this.inputConf,
null, inputName, mConf);
if (getLogger().isDebugEnabled()) {
getLogger().debug("returning an " + (obj == null ? "null" : obj.getClass().getName()) +
" as " + obj);
}
return obj;
}
}