Java tutorial
/***************************************************************** * 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.cayenne.modeler; import java.io.File; import java.util.Iterator; import java.util.Map; import java.util.concurrent.ConcurrentHashMap; import javax.swing.JOptionPane; import javax.swing.SwingUtilities; import org.apache.cayenne.configuration.DataChannelDescriptor; import org.apache.cayenne.map.DataMap; import org.apache.cayenne.modeler.action.OpenProjectAction; import org.apache.cayenne.modeler.action.SaveAction; import org.apache.cayenne.modeler.dialog.FileDeletedDialog; import org.apache.cayenne.project.Project; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; /** * ProjectWatchdog class is responsible for tracking changes in cayenne.xml and * other Cayenne project files * */ public class ProjectFileChangeTracker extends Thread { private static final Log log = LogFactory.getLog(ProjectFileChangeTracker.class); /** * The default delay between every file modification check */ private static final long DEFAULT_DELAY = 4000; /** * The names of the files to observe for changes. */ protected Map<String, FileInfo> files; protected boolean paused; protected ProjectController mediator; public ProjectFileChangeTracker(ProjectController mediator) { this.files = new ConcurrentHashMap<>(); this.mediator = mediator; setName("cayenne-modeler-file-change-tracker"); } /** * Reloads files to watch from the project. Useful when project's structure * has changed */ public void reconfigure() { pauseWatching(); removeAllFiles(); Project project = mediator.getProject(); // check if project exists and has been saved at least once. if (project != null && project.getConfigurationResource() != null) { String projectPath = project.getConfigurationResource().getURL().getPath() + File.separator; addFile(projectPath); Iterator<DataMap> it = ((DataChannelDescriptor) project.getRootNode()).getDataMaps().iterator(); while (it.hasNext()) { DataMap dm = it.next(); addFile(dm.getConfigurationSource().getURL().getPath()); } } resumeWatching(); } protected void doOnChange() { SwingUtilities.invokeLater(new Runnable() { public void run() { if (showConfirmation("One or more project files were changed by external program. " + "Do you want to load the changes?")) { // Currently we are reloading all project if (mediator.getProject() != null) { File fileDirectory = new File( mediator.getProject().getConfigurationResource().getURL().getPath()); Application.getInstance().getActionManager().getAction(OpenProjectAction.class) .openProject(fileDirectory); } } else { mediator.setDirty(true); } } }); } protected void doOnRemove() { if (mediator.getProject() != null) { SwingUtilities.invokeLater(new Runnable() { public void run() { FileDeletedDialog dialog = new FileDeletedDialog(Application.getFrame()); dialog.show(); if (dialog.shouldSave()) { Application.getInstance().getActionManager().getAction(SaveAction.class) .performAction(null); } else if (dialog.shouldClose()) { Application.getInstance().getFrameController().projectClosedAction(); } else { mediator.setDirty(true); } } }); } } /** * Shows confirmation dialog */ private boolean showConfirmation(String message) { return JOptionPane.YES_OPTION == JOptionPane.showConfirmDialog(Application.getFrame(), message, "File changed", JOptionPane.YES_NO_OPTION, JOptionPane.QUESTION_MESSAGE); } /** * Adds a new file to watch * * @param location * path of file */ public void addFile(String location) { try { files.put(location, new FileInfo(location)); } catch (SecurityException e) { log.error("SecurityException adding file " + location, e); } } /** * Turns off watching for a specified file * * @param location * path of file */ public void removeFile(String location) { files.remove(location); } /** * Turns off watching for all files */ public void removeAllFiles() { files.clear(); } protected void check() { if (paused) { return; } boolean hasChanges = false; boolean hasDeletions = false; for (Iterator<FileInfo> it = files.values().iterator(); it.hasNext();) { FileInfo fi = it.next(); boolean fileExists; try { fileExists = fi.getFile().exists(); } catch (SecurityException e) { log.error("SecurityException checking file " + fi.getFile().getPath(), e); // we still process with other files continue; } if (fileExists) { // this can also throw a SecurityException long l = fi.getFile().lastModified(); if (l > fi.getLastModified()) { // however, if we reached this point this is very unlikely. fi.setLastModified(l); hasChanges = true; } } // the file has been removed else if (fi.getLastModified() != -1) { hasDeletions = true; it.remove(); // no point to watch the file now } } if (hasDeletions) { doOnRemove(); } else if (hasChanges) { doOnChange(); } } public void run() { while (true) { try { Thread.sleep(DEFAULT_DELAY); check(); } catch (InterruptedException e) { // someone asked to stop return; } } } /** * Tells watcher to pause watching for some time. Useful before changing * files */ public void pauseWatching() { paused = true; } /** * Resumes watching for files */ public void resumeWatching() { paused = false; } /** * Class to store information about files (last modification time & File * pointer) */ protected class FileInfo { /** * Exact java.io.File object, may not be null */ File file; /** * Time the file was modified */ long lastModified; /** * Creates new object * * @param location * the file path */ public FileInfo(String location) { file = new File(location); lastModified = file.exists() ? file.lastModified() : -1; } public File getFile() { return file; } public long getLastModified() { return lastModified; } public void setLastModified(long l) { lastModified = l; } } }