The UI uses <code>AuxiliaryConfiguration</code> to store list of files opened

   in the project in an instant closing the project. Will be used for reopen these

   files when this project opens.

import java.net.MalformedURLException;

import java.net.URL;

import org.netbeans.spi.project.AuxiliaryConfiguration;

import org.openide.cookies.EditCookie;

import org.openide.cookies.OpenCookie;

import org.openide.filesystems.FileStateInvalidException;

import org.openide.filesystems.URLMapper;

import org.openide.loaders.DataObjectNotFoundException;

    static final String OPEN_FILES_NS = "http://www.netbeans.org/ns/projectui-open-files/1"; // NOI18N

    static final String OPEN_FILES_ELEMENT = "open-files"; // NOI18N

    static final String FILE_ELEMENT = "file"; // NOI18N

    }

    /** Closes all documents in editor area which are owned by one of given projects.

     * If some documents are modified then an user is notified by Save/Discard/Cancel dialog.

     * Dialog is showed only once for all project's documents together.

     * If 'storeDocuments' is true then URLs of closed documents are store to private

     * <code>project.xml</code>.

     *

     * @param p project to close

     * @param storeDocuments will be documents stored to private

     * @return false if an user cancel the Save/Discard/Cancel dialog, true otherwise

     */    

    public static boolean closeAllDocuments (Project[] projects, boolean storeDocuments) {

        if (projects == null) {

            throw new IllegalArgumentException ("No proects are specified."); // NOI18N

        }

        if (projects.length == 0) {

            // no projects to close, no documents will be closed

            return true;

        }

        List/*<Project>*/ listOfProjects = Arrays.asList (projects);

        Set/*<DataObject>*/ openFiles = new HashSet ();

        Set/*<TopComponent>*/ tc2close = new HashSet ();

        Map/*<Project, SortedSet<String>>*/ urls4project = new HashMap ();

        Mode editorMode = WindowManager.getDefault ().findMode (CloneableEditorSupport.EDITOR_MODE);

        TopComponent[] openTCs = editorMode.getTopComponents ();

        for (int i = 0; i < openTCs.length; i++) {

            DataObject dobj = (DataObject) openTCs[i].getLookup ().lookup (DataObject.class);

            if (dobj != null) {

              FileObject fobj = dobj.getPrimaryFile ();

              Project owner = FileOwnerQuery.getOwner (fobj);

              if (listOfProjects.contains (owner)) {

                  openFiles.add (dobj);

                  tc2close.add (openTCs[i]);

                  if (!urls4project.containsKey (owner)) {

                      // add project

                      urls4project.put (owner, new TreeSet ());

                  }

                  URL url = null;

                  try {

                      url = dobj.getPrimaryFile ().getURL ();

                      ((SortedSet)urls4project.get (owner)).add (url.toExternalForm ());

                  } catch (FileStateInvalidException fsie) {

                      assert false : "FileStateInvalidException in " + dobj.getPrimaryFile ();

                  }

              }

            }

        }

        if (openFiles.isEmpty ()) {

            return true;

        }

        boolean result = ExitDialog.showDialog (openFiles);

        if (result) {

            // store project's documents

            // loop all project being closed

            Iterator loop = urls4project.keySet ().iterator ();

            Project p;

            while (loop.hasNext ()) {

                p = (Project) loop.next ();

                storeProjectOpenFiles (p, (SortedSet)urls4project.get (p));

            }

            // close documents

            Iterator it = tc2close.iterator ();

            while (it.hasNext ()) {

                ((TopComponent)it.next ()).close ();

            }

        }

        return result;

    }

    static private void storeProjectOpenFiles (Project p, SortedSet/*<String>*/ urls) {

        AuxiliaryConfiguration aux = (AuxiliaryConfiguration) p.getLookup ().lookup (AuxiliaryConfiguration.class);

        if (aux != null) {

            // clean-up files before adding new one

            aux.removeConfigurationFragment (OPEN_FILES_ELEMENT, OPEN_FILES_NS, false);

            Document xml = XMLUtil.createDocument (OPEN_FILES_ELEMENT, OPEN_FILES_NS, null, null);

            Element fileEl;

            Element openFiles = xml.createElementNS (OPEN_FILES_NS, OPEN_FILES_ELEMENT);

            // loop all open files of given project

            Iterator it = urls.iterator ();

            while (it.hasNext ()) {

                fileEl = openFiles.getOwnerDocument ().createElement (FILE_ELEMENT);

                fileEl.appendChild (fileEl.getOwnerDocument ().createTextNode ((String)it.next ()));

                openFiles.appendChild (fileEl);

            }

            aux.putConfigurationFragment (openFiles, false);

        }

    }

    /** Opens the project's files read from the private <code>project.xml</code> file

     * 

     * @param p project

     */

    public static void openProjectFiles (Project p) {

        AuxiliaryConfiguration aux = (AuxiliaryConfiguration) p.getLookup ().lookup (AuxiliaryConfiguration.class);

        if (aux == null) {

            return ;

        }

        Element openFiles = aux.getConfigurationFragment (OPEN_FILES_ELEMENT, OPEN_FILES_NS, false);

        if (openFiles == null) {

            return;

        }

        NodeList list = openFiles.getElementsByTagName (FILE_ELEMENT);

        if (list == null) {

            return ;

        }

        FileObject fo = null;

        DataObject dobj;

        String url;

        for (int i = 0; i < list.getLength (); i++) {

            url = list.item (i).getChildNodes ().item (0).getNodeValue ();

            try {

                fo = URLMapper.findFileObject (new URL (url));

                if (fo == null) {

                    continue;

                }

                dobj = DataObject.find (fo);

                EditCookie ec = (EditCookie) dobj.getCookie (EditCookie.class);

                OpenCookie oc = (OpenCookie) dobj.getCookie (OpenCookie.class);

                if (ec != null) {

                    ((EditCookie) ec).edit ();

                } else if (oc != null) {

                    ((OpenCookie) oc).open ();

                }

            } catch (MalformedURLException mue) {

                assert false : "MalformedURLException in " + url;

            } catch (DataObjectNotFoundException donfo) {

                assert false : "DataObject must exist for " + fo;

            }

        }

        // clean-up stored files

        aux.removeConfigurationFragment (OPEN_FILES_ELEMENT, OPEN_FILES_NS, false);

import org.netbeans.modules.project.ui.ProjectUtilities;

                    // open project files

                    ProjectUtilities.openProjectFiles (project);

<?xml version="1.0" encoding="UTF-8"?>

<!--

                Sun Public License Notice

The contents of this file are subject to the Sun Public License

Version 1.0 (the "License"). You may not use this file except in

compliance with the License. A copy of the License is available at

http://www.sun.com/

The Original Code is NetBeans. The Initial Developer of the Original

Code is Sun Microsystems, Inc. Portions Copyright 1997-2004 Sun

Microsystems, Inc. All Rights Reserved.

-->

<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"

            targetNamespace="http://www.netbeans.org/ns/projectui-open-files/1"

            xmlns="http://www.netbeans.org/ns/projectui-open-files/1"

            elementFormDefault="qualified">

    <xsd:element name="open-files">

        <xsd:complexType>

            <xsd:sequence>

                <xsd:element name="file" minOccurs="0" maxOccurs="unbounded" type="xsd:anyURI"/>

            </xsd:sequence>

        </xsd:complexType>

    </xsd:element>

</xsd:schema>