org.apache.cocoon.components.modules.input.JXPathMetaModule Maven / Gradle / Ivy

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/*
 * 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.
 *
 * Note: This is based on the AbstractJXPathModule
 * and duplicates the code since multiple inheritance is not possible.
 * Please keep both classes in sync.
 *
 * Configuration example:
 * 
 * 
 *   
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 *   
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 *   
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 * <lenient>false</lenient> When set to true, non-existing attributes return null, when set to false,
 *       an exception is thrown. Default is true.
<parameter>false</parameter> Attribute name to be used instead of passed attribute name.
<from-parameter>false</from-parameter> Attribute name to pass to configured input module
<input-module name="request-attr"/> Uses the "request-attr" input module to obtain a value and
 *       applies the given JXPath expression to it.
<function name="java.lang.String" prefix="str"/> 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.
<package name="java.util" prefix="util"/> 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.
<namespace uri="uri:foo" prefix="bar"/> Registers the namespace identified by URI uri:foo
 *   with the JXPathContext using the prefix bar. Thus
 *   expressions can query XML with nodes in this namespace using
 *   registered prefix.
 *
 * 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.
 *
 * @version $Id: JXPathMetaModule.java 609282 2008-01-06 09:35:48Z rgoers $
 */
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 Configuration value
     * @exception ConfigurationException if an error occurs
     */
    /**
     * @see org.apache.cocoon.components.modules.input.AbstractInputModule#configure(org.apache.avalon.framework.configuration.Configuration)
     */
    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);
    }

    /**
     * @see org.apache.cocoon.components.modules.input.AbstractInputModule#getAttribute(java.lang.String, org.apache.avalon.framework.configuration.Configuration, java.util.Map)
     */
    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);
    }

    /**
     * @see org.apache.cocoon.components.modules.input.AbstractInputModule#getAttributeNames(org.apache.avalon.framework.configuration.Configuration, java.util.Map)
     */
    public Iterator getAttributeNames(Configuration modeConf, Map objectModel)
    throws ConfigurationException {
        Object contextObj = getContextObject(modeConf, objectModel);
        return JXPathHelper.getAttributeNames(this.configuration, contextObj);
    }

    /**
     * @see org.apache.cocoon.components.modules.input.AbstractInputModule#getAttributeValues(java.lang.String, org.apache.avalon.framework.configuration.Configuration, java.util.Map)
     */
    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 Configuration value
     * @param objectModel a Map value
     * @return an Object value
     * @throws ConfigurationException from called components.
     */
    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;
    }
}

`<lenient>false</lenient>`	When set to true, non-existing attributes return null, when set to false, * an exception is thrown. Default is true.
`<parameter>false</parameter>`	Attribute name to be used instead of passed attribute name.
`<from-parameter>false</from-parameter>`	Attribute name to pass to configured input module
`<input-module name="request-attr"/>`	Uses the "request-attr" input module to obtain a value and * applies the given JXPath expression to it.
`<function name="java.lang.String" prefix="str"/>`	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.
`<package name="java.util" prefix="util"/>`	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.
`<namespace uri="uri:foo" prefix="bar"/>`	Registers the namespace identified by URI `uri:foo` * with the JXPathContext using the prefix `bar`. Thus * expressions can query XML with nodes in this namespace using * registered prefix.