Java tutorial
/* * Copyright (c) 1998, 2017, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.swing.filechooser; import java.awt.Image; import java.beans.PropertyChangeListener; import java.io.File; import java.io.FileNotFoundException; import java.io.IOException; import java.lang.ref.WeakReference; import java.security.AccessController; import java.security.PrivilegedAction; import java.text.MessageFormat; import java.util.ArrayList; import java.util.List; import javax.swing.Icon; import javax.swing.ImageIcon; import javax.swing.JFileChooser; import javax.swing.UIManager; import jdk.internal.ref.CleanerFactory; import sun.awt.shell.ShellFolder; /** * FileSystemView is JFileChooser's gateway to the * file system. Since the JDK1.1 File API doesn't allow * access to such information as root partitions, file type * information, or hidden file bits, this class is designed * to intuit as much OS-specific file system information as * possible. * * <p> * * Java Licensees may want to provide a different implementation of * FileSystemView to better handle a given operating system. * * @author Jeff Dinkins */ // PENDING(jeff) - need to provide a specification for // how Mac/OS2/BeOS/etc file systems can modify FileSystemView // to handle their particular type of file system. public abstract class FileSystemView { static FileSystemView windowsFileSystemView = null; static FileSystemView unixFileSystemView = null; //static FileSystemView macFileSystemView = null; static FileSystemView genericFileSystemView = null; private boolean useSystemExtensionHiding = UIManager.getDefaults() .getBoolean("FileChooser.useSystemExtensionHiding"); /** * Returns the file system view. * @return the file system view */ public static FileSystemView getFileSystemView() { if (File.separatorChar == '\\') { if (windowsFileSystemView == null) { windowsFileSystemView = new WindowsFileSystemView(); } return windowsFileSystemView; } if (File.separatorChar == '/') { if (unixFileSystemView == null) { unixFileSystemView = new UnixFileSystemView(); } return unixFileSystemView; } // if(File.separatorChar == ':') { // if(macFileSystemView == null) { // macFileSystemView = new MacFileSystemView(); // } // return macFileSystemView; //} if (genericFileSystemView == null) { genericFileSystemView = new GenericFileSystemView(); } return genericFileSystemView; } /** * Constructs a FileSystemView. */ public FileSystemView() { final WeakReference<FileSystemView> weakReference = new WeakReference<>(this); final PropertyChangeListener pcl = evt -> { final FileSystemView fsv = weakReference.get(); if (fsv != null && evt.getPropertyName().equals("lookAndFeel")) { fsv.useSystemExtensionHiding = UIManager.getDefaults() .getBoolean("FileChooser.useSystemExtensionHiding"); } }; UIManager.addPropertyChangeListener(pcl); CleanerFactory.cleaner().register(this, () -> { UIManager.removePropertyChangeListener(pcl); }); } /** * Determines if the given file is a root in the navigable tree(s). * Examples: Windows 98 has one root, the Desktop folder. DOS has one root * per drive letter, <code>C:\</code>, <code>D:\</code>, etc. Unix has one root, * the <code>"/"</code> directory. * * The default implementation gets information from the <code>ShellFolder</code> class. * * @param f a <code>File</code> object representing a directory * @return <code>true</code> if <code>f</code> is a root in the navigable tree. * @see #isFileSystemRoot */ public boolean isRoot(File f) { if (f == null || !f.isAbsolute()) { return false; } File[] roots = getRoots(); for (File root : roots) { if (root.equals(f)) { return true; } } return false; } /** * Returns true if the file (directory) can be visited. * Returns false if the directory cannot be traversed. * * @param f the <code>File</code> * @return <code>true</code> if the file/directory can be traversed, otherwise <code>false</code> * @see JFileChooser#isTraversable * @see FileView#isTraversable * @since 1.4 */ public Boolean isTraversable(File f) { return Boolean.valueOf(f.isDirectory()); } /** * Name of a file, directory, or folder as it would be displayed in * a system file browser. Example from Windows: the "M:\" directory * displays as "CD-ROM (M:)" * * The default implementation gets information from the ShellFolder class. * * @param f a <code>File</code> object * @return the file name as it would be displayed by a native file chooser * @see JFileChooser#getName * @since 1.4 */ public String getSystemDisplayName(File f) { if (f == null) { return null; } String name = f.getName(); if (!name.equals("..") && !name.equals(".") && (useSystemExtensionHiding || !isFileSystem(f) || isFileSystemRoot(f)) && (f instanceof ShellFolder || f.exists())) { try { name = getShellFolder(f).getDisplayName(); } catch (FileNotFoundException e) { return null; } if (name == null || name.length() == 0) { name = f.getPath(); // e.g. "/" } } return name; } /** * Type description for a file, directory, or folder as it would be displayed in * a system file browser. Example from Windows: the "Desktop" folder * is described as "Desktop". * * Override for platforms with native ShellFolder implementations. * * @param f a <code>File</code> object * @return the file type description as it would be displayed by a native file chooser * or null if no native information is available. * @see JFileChooser#getTypeDescription * @since 1.4 */ public String getSystemTypeDescription(File f) { return null; } /** * Icon for a file, directory, or folder as it would be displayed in * a system file browser. Example from Windows: the "M:\" directory * displays a CD-ROM icon. * * The default implementation gets information from the ShellFolder class. * * @param f a <code>File</code> object * @return an icon as it would be displayed by a native file chooser * @see JFileChooser#getIcon * @since 1.4 */ public Icon getSystemIcon(File f) { if (f == null) { return null; } ShellFolder sf; try { sf = getShellFolder(f); } catch (FileNotFoundException e) { return null; } Image img = sf.getIcon(false); if (img != null) { return new ImageIcon(img, sf.getFolderType()); } else { return UIManager.getIcon(f.isDirectory() ? "FileView.directoryIcon" : "FileView.fileIcon"); } } /** * On Windows, a file can appear in multiple folders, other than its * parent directory in the filesystem. Folder could for example be the * "Desktop" folder which is not the same as file.getParentFile(). * * @param folder a <code>File</code> object representing a directory or special folder * @param file a <code>File</code> object * @return <code>true</code> if <code>folder</code> is a directory or special folder and contains <code>file</code>. * @since 1.4 */ public boolean isParent(File folder, File file) { if (folder == null || file == null) { return false; } else if (folder instanceof ShellFolder) { File parent = file.getParentFile(); if (parent != null && parent.equals(folder)) { return true; } File[] children = getFiles(folder, false); for (File child : children) { if (file.equals(child)) { return true; } } return false; } else { return folder.equals(file.getParentFile()); } } /** * * @param parent a <code>File</code> object representing a directory or special folder * @param fileName a name of a file or folder which exists in <code>parent</code> * @return a File object. This is normally constructed with <code>new * File(parent, fileName)</code> except when parent and child are both * special folders, in which case the <code>File</code> is a wrapper containing * a <code>ShellFolder</code> object. * @since 1.4 */ public File getChild(File parent, String fileName) { if (parent instanceof ShellFolder) { File[] children = getFiles(parent, false); for (File child : children) { if (child.getName().equals(fileName)) { return child; } } } return createFileObject(parent, fileName); } /** * Checks if <code>f</code> represents a real directory or file as opposed to a * special folder such as <code>"Desktop"</code>. Used by UI classes to decide if * a folder is selectable when doing directory choosing. * * @param f a <code>File</code> object * @return <code>true</code> if <code>f</code> is a real file or directory. * @since 1.4 */ public boolean isFileSystem(File f) { if (f instanceof ShellFolder) { ShellFolder sf = (ShellFolder) f; // Shortcuts to directories are treated as not being file system objects, // so that they are never returned by JFileChooser. return sf.isFileSystem() && !(sf.isLink() && sf.isDirectory()); } else { return true; } } /** * Creates a new folder with a default folder name. * * @param containingDir a {@code File} object denoting directory to contain the new folder * @return a {@code File} object denoting the newly created folder * @throws IOException if new folder could not be created */ public abstract File createNewFolder(File containingDir) throws IOException; /** * Returns whether a file is hidden or not. * * @param f a {@code File} object * @return true if the given {@code File} denotes a hidden file */ public boolean isHiddenFile(File f) { return f.isHidden(); } /** * Is dir the root of a tree in the file system, such as a drive * or partition. Example: Returns true for "C:\" on Windows 98. * * @param dir a <code>File</code> object representing a directory * @return <code>true</code> if <code>f</code> is a root of a filesystem * @see #isRoot * @since 1.4 */ public boolean isFileSystemRoot(File dir) { return ShellFolder.isFileSystemRoot(dir); } /** * Used by UI classes to decide whether to display a special icon * for drives or partitions, e.g. a "hard disk" icon. * * The default implementation has no way of knowing, so always returns false. * * @param dir a directory * @return <code>false</code> always * @since 1.4 */ public boolean isDrive(File dir) { return false; } /** * Used by UI classes to decide whether to display a special icon * for a floppy disk. Implies isDrive(dir). * * The default implementation has no way of knowing, so always returns false. * * @param dir a directory * @return <code>false</code> always * @since 1.4 */ public boolean isFloppyDrive(File dir) { return false; } /** * Used by UI classes to decide whether to display a special icon * for a computer node, e.g. "My Computer" or a network server. * * The default implementation has no way of knowing, so always returns false. * * @param dir a directory * @return <code>false</code> always * @since 1.4 */ public boolean isComputerNode(File dir) { return ShellFolder.isComputerNode(dir); } /** * Returns all root partitions on this system. For example, on * Windows, this would be the "Desktop" folder, while on DOS this * would be the A: through Z: drives. * * @return an array of {@code File} objects representing all root partitions * on this system */ public File[] getRoots() { // Don't cache this array, because filesystem might change File[] roots = (File[]) ShellFolder.get("roots"); for (int i = 0; i < roots.length; i++) { if (isFileSystemRoot(roots[i])) { roots[i] = createFileSystemRoot(roots[i]); } } return roots; } // Providing default implementations for the remaining methods // because most OS file systems will likely be able to use this // code. If a given OS can't, override these methods in its // implementation. /** * Returns the home directory. * @return the home directory */ public File getHomeDirectory() { return createFileObject(System.getProperty("user.home")); } /** * Return the user's default starting directory for the file chooser. * * @return a <code>File</code> object representing the default * starting folder * @since 1.4 */ public File getDefaultDirectory() { File f = (File) ShellFolder.get("fileChooserDefaultFolder"); if (isFileSystemRoot(f)) { f = createFileSystemRoot(f); } return f; } /** * Returns a File object constructed in dir from the given filename. * * @param dir an abstract pathname denoting a directory * @param filename a {@code String} representation of a pathname * @return a {@code File} object created from {@code dir} and {@code filename} */ public File createFileObject(File dir, String filename) { if (dir == null) { return new File(filename); } else { return new File(dir, filename); } } /** * Returns a File object constructed from the given path string. * * @param path {@code String} representation of path * @return a {@code File} object created from the given {@code path} */ public File createFileObject(String path) { File f = new File(path); if (isFileSystemRoot(f)) { f = createFileSystemRoot(f); } return f; } /** * Gets the list of shown (i.e. not hidden) files. * * @param dir the root directory of files to be returned * @param useFileHiding determine if hidden files are returned * @return an array of {@code File} objects representing files and * directories in the given {@code dir}. It includes hidden * files if {@code useFileHiding} is false. */ public File[] getFiles(File dir, boolean useFileHiding) { List<File> files = new ArrayList<File>(); // add all files in dir if (!(dir instanceof ShellFolder)) { try { dir = getShellFolder(dir); } catch (FileNotFoundException e) { return new File[0]; } } File[] names = ((ShellFolder) dir).listFiles(!useFileHiding); if (names == null) { return new File[0]; } for (File f : names) { if (Thread.currentThread().isInterrupted()) { break; } if (!(f instanceof ShellFolder)) { if (isFileSystemRoot(f)) { f = createFileSystemRoot(f); } try { f = ShellFolder.getShellFolder(f); } catch (FileNotFoundException e) { // Not a valid file (wouldn't show in native file chooser) // Example: C:\pagefile.sys continue; } catch (InternalError e) { // Not a valid file (wouldn't show in native file chooser) // Example C:\Winnt\Profiles\joe\history\History.IE5 continue; } } if (!useFileHiding || !isHiddenFile(f)) { files.add(f); } } return files.toArray(new File[files.size()]); } /** * Returns the parent directory of <code>dir</code>. * @param dir the <code>File</code> being queried * @return the parent directory of <code>dir</code>, or * <code>null</code> if <code>dir</code> is <code>null</code> */ public File getParentDirectory(File dir) { if (dir == null || !dir.exists()) { return null; } ShellFolder sf; try { sf = getShellFolder(dir); } catch (FileNotFoundException e) { return null; } File psf = sf.getParentFile(); if (psf == null) { return null; } if (isFileSystem(psf)) { File f = psf; if (!f.exists()) { // This could be a node under "Network Neighborhood". File ppsf = psf.getParentFile(); if (ppsf == null || !isFileSystem(ppsf)) { // We're mostly after the exists() override for windows below. f = createFileSystemRoot(f); } } return f; } else { return psf; } } /** * Returns an array of files representing the values which will be shown * in the file chooser selector. * * @return an array of {@code File} objects. The array returned may be * possibly empty if there are no appropriate permissions. * @since 9 */ public File[] getChooserComboBoxFiles() { return (File[]) ShellFolder.get("fileChooserComboBoxFolders"); } /** * Returns an array of files representing the values to show by default in * the file chooser shortcuts panel. * * @return an array of {@code File} objects. The array returned may be * possibly empty if there are no appropriate permissions. * @since 12 */ final public File[] getChooserShortcutPanelFiles() { return (File[]) ShellFolder.get("fileChooserShortcutPanelFolders"); } /** * Returns whether the specified file denotes a shell interpreted link which * can be obtained by the {@link #getLinkLocation(File)}. * * @param file a file * @return whether this is a link * @throws NullPointerException if {@code file} equals {@code null} * @throws SecurityException if the caller does not have necessary * permissions * @see #getLinkLocation(File) * @since 9 */ public boolean isLink(File file) { if (file == null) { throw new NullPointerException("file is null"); } try { return ShellFolder.getShellFolder(file).isLink(); } catch (FileNotFoundException e) { return false; } } /** * Returns the regular file referenced by the specified link file if * the specified file is a shell interpreted link. * Returns {@code null} if the specified file is not * a shell interpreted link. * * @param file a file * @return the linked file or {@code null}. * @throws FileNotFoundException if the linked file does not exist * @throws NullPointerException if {@code file} equals {@code null} * @throws SecurityException if the caller does not have necessary * permissions * @since 9 */ public File getLinkLocation(File file) throws FileNotFoundException { if (file == null) { throw new NullPointerException("file is null"); } ShellFolder shellFolder; try { shellFolder = ShellFolder.getShellFolder(file); } catch (FileNotFoundException e) { return null; } return shellFolder.isLink() ? shellFolder.getLinkLocation() : null; } /** * Throws {@code FileNotFoundException} if file not found or current thread was interrupted */ ShellFolder getShellFolder(File f) throws FileNotFoundException { if (!(f instanceof ShellFolder) && !(f instanceof FileSystemRoot) && isFileSystemRoot(f)) { f = createFileSystemRoot(f); } try { return ShellFolder.getShellFolder(f); } catch (InternalError e) { System.err.println("FileSystemView.getShellFolder: f=" + f); e.printStackTrace(); return null; } } /** * Creates a new <code>File</code> object for <code>f</code> with correct * behavior for a file system root directory. * * @param f a <code>File</code> object representing a file system root * directory, for example "/" on Unix or "C:\" on Windows. * @return a new <code>File</code> object * @since 1.4 */ protected File createFileSystemRoot(File f) { return new FileSystemRoot(f); } @SuppressWarnings("serial") // Same-version serialization only static class FileSystemRoot extends File { public FileSystemRoot(File f) { super(f, ""); } public FileSystemRoot(String s) { super(s); } public boolean isDirectory() { return true; } public String getName() { return getPath(); } } } /** * FileSystemView that handles some specific unix-isms. */ class UnixFileSystemView extends FileSystemView { private static final String newFolderString = UIManager.getString("FileChooser.other.newFolder"); private static final String newFolderNextString = UIManager.getString("FileChooser.other.newFolder.subsequent"); /** * Creates a new folder with a default folder name. */ public File createNewFolder(File containingDir) throws IOException { if (containingDir == null) { throw new IOException("Containing directory is null:"); } File newFolder; // Unix - using OpenWindows' default folder name. Can't find one for Motif/CDE. newFolder = createFileObject(containingDir, newFolderString); int i = 1; while (newFolder.exists() && i < 100) { newFolder = createFileObject(containingDir, MessageFormat.format(newFolderNextString, i)); i++; } if (newFolder.exists()) { throw new IOException("Directory already exists:" + newFolder.getAbsolutePath()); } else { if (!newFolder.mkdirs()) { throw new IOException(newFolder.getAbsolutePath()); } } return newFolder; } public boolean isFileSystemRoot(File dir) { return dir != null && dir.getAbsolutePath().equals("/"); } public boolean isDrive(File dir) { return isFloppyDrive(dir); } public boolean isFloppyDrive(File dir) { // Could be looking at the path for Solaris, but wouldn't be reliable. // For example: // return (dir != null && dir.getAbsolutePath().toLowerCase().startsWith("/floppy")); return false; } public boolean isComputerNode(File dir) { if (dir != null) { String parent = dir.getParent(); if (parent != null && parent.equals("/net")) { return true; } } return false; } } /** * FileSystemView that handles some specific windows concepts. */ class WindowsFileSystemView extends FileSystemView { private static final String newFolderString = UIManager.getString("FileChooser.win32.newFolder"); private static final String newFolderNextString = UIManager.getString("FileChooser.win32.newFolder.subsequent"); public Boolean isTraversable(File f) { return Boolean.valueOf(isFileSystemRoot(f) || isComputerNode(f) || f.isDirectory()); } public File getChild(File parent, String fileName) { if (fileName.startsWith("\\") && !fileName.startsWith("\\\\") && isFileSystem(parent)) { //Path is relative to the root of parent's drive String path = parent.getAbsolutePath(); if (path.length() >= 2 && path.charAt(1) == ':' && Character.isLetter(path.charAt(0))) { return createFileObject(path.substring(0, 2) + fileName); } } return super.getChild(parent, fileName); } /** * Type description for a file, directory, or folder as it would be displayed in * a system file browser. Example from Windows: the "Desktop" folder * is described as "Desktop". * * The Windows implementation gets information from the ShellFolder class. */ public String getSystemTypeDescription(File f) { if (f == null) { return null; } try { return getShellFolder(f).getFolderType(); } catch (FileNotFoundException e) { return null; } } /** * @return the Desktop folder. */ public File getHomeDirectory() { File[] roots = getRoots(); return (roots.length == 0) ? null : roots[0]; } /** * Creates a new folder with a default folder name. */ public File createNewFolder(File containingDir) throws IOException { if (containingDir == null) { throw new IOException("Containing directory is null:"); } // Using NT's default folder name File newFolder = createFileObject(containingDir, newFolderString); int i = 2; while (newFolder.exists() && i < 100) { newFolder = createFileObject(containingDir, MessageFormat.format(newFolderNextString, i)); i++; } if (newFolder.exists()) { throw new IOException("Directory already exists:" + newFolder.getAbsolutePath()); } else { if (!newFolder.mkdirs()) { throw new IOException(newFolder.getAbsolutePath()); } } return newFolder; } public boolean isDrive(File dir) { return isFileSystemRoot(dir); } public boolean isFloppyDrive(final File dir) { String path = AccessController.doPrivileged(new PrivilegedAction<String>() { public String run() { return dir.getAbsolutePath(); } }); return path != null && (path.equals("A:\\") || path.equals("B:\\")); } /** * Returns a File object constructed from the given path string. */ public File createFileObject(String path) { // Check for missing backslash after drive letter such as "C:" or "C:filename" if (path.length() >= 2 && path.charAt(1) == ':' && Character.isLetter(path.charAt(0))) { if (path.length() == 2) { path += "\\"; } else if (path.charAt(2) != '\\') { path = path.substring(0, 2) + "\\" + path.substring(2); } } return super.createFileObject(path); } @SuppressWarnings("serial") // anonymous class protected File createFileSystemRoot(File f) { // Problem: Removable drives on Windows return false on f.exists() // Workaround: Override exists() to always return true. return new FileSystemRoot(f) { public boolean exists() { return true; } }; } } /** * Fallthrough FileSystemView in case we can't determine the OS. */ class GenericFileSystemView extends FileSystemView { private static final String newFolderString = UIManager.getString("FileChooser.other.newFolder"); /** * Creates a new folder with a default folder name. */ public File createNewFolder(File containingDir) throws IOException { if (containingDir == null) { throw new IOException("Containing directory is null:"); } // Using NT's default folder name File newFolder = createFileObject(containingDir, newFolderString); if (newFolder.exists()) { throw new IOException("Directory already exists:" + newFolder.getAbsolutePath()); } else { if (!newFolder.mkdirs()) { throw new IOException(newFolder.getAbsolutePath()); } } return newFolder; } }