xmltreefactory.java

jsp + xmｌ实现ｔｒｅｅｖｉｅｗ

/*
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 * 2. Redistributions in binary form must reproduce the above copyright
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 *    Alternately, this acknowledgment may appear in the software itself,
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package net.sf.jsptree.tree;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.FactoryConfigurationError;
import javax.xml.parsers.ParserConfigurationException;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.*;

import org.apache.log4j.Logger;
import org.w3c.dom.*;
import org.xml.sax.SAXException;

import net.sf.jsptree.component.JSPTreeNodeImpl;

/**
 * Represents a TreeFactory for building {@link TreeStructureModel} instances from
 * specified XML file. All of the trees it returns have a common {@link TreeStructureModel}
 * interface. It needs to keep track of whether or not a
 * particular {@link Tree} instance has been generated yet from XML file and that's
 * why it represents <i>Singleton</i> pattern. It does not build tree
 * instance each time it is requested, but use <i>Cloneable</i> mechanism
 * of <code>TreeStructureModel</code> instead. In short, it parses XML file only once and then
 * uses {@link TreeStructureModel#clone} method in order to return new <code>TreeStructureModel</code>
 * instances.
 * <p/>
 * Actually this class represents <code>Abstract Factory</code> too. Because its
 * {@link #getInstance} method builds new instance of <code>TreeFactory</code>
 * per unique XML path and share these <code>Factories</code> between clients.
 *
 * @author Vladislav Kamensky
 */
public class XMLTreeFactory implements TreeFactory {

    /**
     * Logger instance.
     */
    private static Logger LOG = Logger.getLogger(XMLTreeFactory.class);

    private static Map m_instances = new HashMap();

    private Map m_treeStructuresMap = null;

    private Map m_treeStatesMap = null;

    /**
     * Path to XML file, which represents trees' definitions.
     */
    private String m_pathToXMLTree = null;

    /**
     * Constructs new <code>XMLTreeFactory</code> instance and
     * builds XML trees from spesified path.
     */
    private XMLTreeFactory(String p_pathToXMLTree) throws TreeFactoryException {
        m_pathToXMLTree = p_pathToXMLTree;
        m_treeStructuresMap = new HashMap();
        m_treeStatesMap = new HashMap();
        for (Iterator wrappers = buildTree().entrySet().iterator(); wrappers.hasNext();) {
            Map.Entry entry = (Map.Entry) wrappers.next();
            Wrapper wrapper = (Wrapper) entry.getValue();
            m_treeStructuresMap.put(entry.getKey(), wrapper.getStructureModel());
            m_treeStatesMap.put(entry.getKey(), wrapper.getStateModel());
        }
    }

    /**
     * Creates (if necessary) a <code>TreeFactory</code> instance and returns it.
     * If the <code>TreeFactory</code> instance with the given XML path has not been
     * generated yet, it is created and cached in order to be shared subsequently.
     *
     * @param p_pathToXMLTree Path to XML file representing trees' definitions.
     * @throws TreeFactoryException in case of specified path can not be resolved
     */
    public synchronized static TreeFactory getInstance(String p_pathToXMLTree) throws TreeFactoryException {
        TreeFactory a_treeFactory = (TreeFactory) m_instances.get(p_pathToXMLTree);

        if (a_treeFactory == null) {
            if (p_pathToXMLTree != null && p_pathToXMLTree.length() > 0) {
                a_treeFactory = new XMLTreeFactory(p_pathToXMLTree);
                m_instances.put(p_pathToXMLTree, a_treeFactory);
                if (LOG.isDebugEnabled()) {
                    LOG.debug("New instance created with path: " + p_pathToXMLTree);
                }
            } else {
                throw new TreeFactoryException("Path to xml tree can not be empty");
            }
        }

        return a_treeFactory;
    }

    /**
     * Returns new <code>TreeStructureModel</code> instance by its name.
     *
     * @param p_name The name of the tree to be built.
     * @throws TreeFactoryException in case of tree with the given
     *                              name can not be built
     */
    public TreeStructureModel getTree(String p_name) throws TreeFactoryException {
        TreeStructureModel a_tree = (TreeStructureModel) m_treeStructuresMap.get(p_name);
        if (a_tree == null) {
            throw new TreeFactoryException("Can not find tree with name: " + p_name);
        }
        try {
            return (TreeStructureModel) a_tree.clone();
        } catch (CloneNotSupportedException ex) {
            throw new TreeFactoryException("CloneNotSupportedException:" + ex.getMessage());
        }
    }

    public TreeStateModel getTreeStates(String p_name) throws TreeFactoryException {
        TreeStateModel a_tree = (TreeStateModel) m_treeStatesMap.get(p_name);
        if (a_tree == null) {
            throw new TreeFactoryException("Can not find tree with name: " + p_name);
        }
        try {
            return (TreeStateModel) a_tree.clone();
        } catch (CloneNotSupportedException ex) {
            throw new TreeFactoryException("CloneNotSupportedException:" + ex.getMessage());
        }
    }

    private Map buildTree() throws TreeFactoryException {

        if (LOG.isInfoEnabled()) {
            LOG.info("started");
        }
        if (m_pathToXMLTree == null) {
            LOG.error("xml tree file was not found");
            throw new TreeFactoryException("xml tree file was not found");

        }
        if (LOG.isDebugEnabled()) {
            LOG.debug("starting to construct tree from: " + m_pathToXMLTree);
        }

        return generateTreeMap(getDocument());
    }

    private Map generateTreeMap(Document p_document) throws TreeFactoryException {
        Map a_map = new HashMap();

        Element a_element = p_document.getDocumentElement();
        p_document.getDocumentElement().normalize();

        if (!a_element.getNodeName().equalsIgnoreCase(XMLTreeConstant.ROOT_ELEMENT)) {
            throw new TreeFactoryException("There is no root element: " + XMLTreeConstant.ROOT_ELEMENT);
        }
        if (a_element.getChildNodes().getLength() == 0) {