fieldxrefmanager.java

java 写的一个新闻发布系统

package org.jahia.content;

import java.util.*;

import org.jahia.utils.JahiaConsole;

/**
 * Title:        Jahia
 * Description:  The purpose of this class is to provide a cross reference
 * system between fields and pages, in order to know which pages reference
 * a field. This is necessary since currently this information is defined
 * only by template developpers and is useful for the HTML cache system when a
 * field modification is done. This class allows lookups such as : "which
 * pages access this field via the absolute field reference system?"
 * Copyright:    Copyright (c) 2002
 * Company:      Jahia Ltd
 * @author Serge Huber
 * @version 1.0
 */

public class FieldXRefManager {

    private static final String NAME_SEPARATOR = "_";

    private static FieldXRefManager theObject = null;

    protected FieldXRefManager() {
        JahiaConsole.println("FieldXRefManager",
                             "Initializing...");
    }

    /**
     * Returns a singleton instance of this service
     * Note : this is a synchronized access method so it might affect performance
     * if a lot of threads must access it simultaneously.
     * @returns the singleton instance.
     */
    public static synchronized FieldXRefManager getInstance()
    {
        if (theObject == null) {
            theObject = new FieldXRefManager();
        }
        return theObject;
    } // end getInstance

    /**
     * Retrieves a list of pageIDs that contain references to a specific
     * absolute field.
     * @param fieldName the name of the field referenced in a
     * absolute way
     * @param fieldSourcePageID the source page on which we are accessing
     * the field
     * @returns a Set of Integers containing pageIDs
     */
    public Set getAbsoluteFieldPageIDs(String siteName,
                                       String fieldName,
                                       int fieldSourcePageID) {

        FieldKey fieldKey = new FieldKey(siteName,
                                         fieldName +
                                         NAME_SEPARATOR +
                                         Integer.toString(fieldSourcePageID));

        Set objectRefs = CrossReferenceManager.getInstance().getObjectXRefs(fieldKey);
        Set pageIDs = new TreeSet();
        if (objectRefs == null) {
            return pageIDs;
        }
        Iterator objectRefIter = objectRefs.iterator();
        while (objectRefIter.hasNext()) {
            Object ref = objectRefIter.next();
            if (ref instanceof ObjectKey) {
                ObjectKey refKey = (ObjectKey) ref;
                if (PageKey.PAGE_TYPE.equals(refKey.getType())) {
                    PageKey pageRefKey = (PageKey) refKey;
                    Integer pageID = new Integer(pageRefKey.getPageID());
                    pageIDs.add(pageID);
                } else {
                    JahiaConsole.println("FieldXRefManager.getAbsoluteFieldPageIDs",
                                         "Expected page type in cross reference list, ignoring value...  ");
                }
            } else {
                JahiaConsole.println("FieldXRefManager.getAbsoluteFieldPageIDs",
                                     "Invalid key object in cross reference list, ignoring... ");
            }
        }
        return pageIDs;
    }

    /**
     * Adds or updates a cross reference between an absolute field and
     * a page
     * @param fieldName the name of the field referenced on a
     * absolute way
     * @param fieldSourcePageID the source page on which we are accessing
     * the field
     * @param pageID the page identifier
     */
    public void setAbsoluteFieldPageID(String siteName,
                                       String fieldName,
                                       int fieldSourcePageID,
                                       int referencePageID) {
        FieldKey fieldKey = new FieldKey(siteName,
                                         fieldName +
                                         NAME_SEPARATOR +
                                         Integer.toString(fieldSourcePageID));
        PageKey pageKey = new PageKey(siteName, referencePageID);
        CrossReferenceManager.getInstance().setObjectXRef(fieldKey, pageKey);
    }

    /**
     * Removes all the cross references for a specified absolute field
     * @param fieldName the name of the field referenced in a
     * absolute way
     * @param fieldSourcePageID the source page on which we are accessing
     * the field
     */
    public void removeAbsoluteField(String siteName,
                                    String fieldName,
                                    int fieldSourcePageID) {
        FieldKey fieldKey = new FieldKey(siteName,
                                         fieldName +
                                         NAME_SEPARATOR +
                                         Integer.toString(fieldSourcePageID));
        CrossReferenceManager.getInstance().removeObjectXRefs(fieldKey);
    }

}