// This example is from _Java Examples in a Nutshell_. (http://www.oreilly.com)
// Copyright (c) 1997 by David Flanagan
// This example is provided WITHOUT ANY WARRANTY either expressed or implied.
// You may study, use, modify, and distribute it for non-commercial purposes.
// For any commercial use, see http://www.davidflanagan.com/javaexamples
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.text.DateFormat;
import java.util.Date;
/**
* This class creates and displays a window containing a list of
* files and sub-directories in a specified directory. Clicking on an
* entry in the list displays more information about it. Double-clicking
* on an entry displays it, if a file, or lists it if a directory.
* An optionally-specified FilenameFilter filters the displayed list.
**/
public class FileLister extends CloseableFrame
implements ActionListener, ItemListener {
private List list; // To display the directory contents in
private TextField details; // To display detail info in.
private Panel buttons; // Holds the buttson
private Button up, close; // The Up and Close buttons
private File currentDir; // The directory currently listed
private FilenameFilter filter; // An optional filter for the directory
private String[] files; // The directory contents
private DateFormat dateFormatter = // To display dates and time correctly
DateFormat.getDateTimeInstance(DateFormat.SHORT, DateFormat.SHORT);
/**
* Constructor: create the GUI, and list the initial directory.
**/
public FileLister(String directory, FilenameFilter filter) {
super("File Lister"); // Create the window
this.filter = filter; // Save the filter, if any
list = new List(12, false); // Set up the list
list.setFont(new Font("MonoSpaced", Font.PLAIN, 14));
list.addActionListener(this);
list.addItemListener(this);
details = new TextField(); // Set up the details area
details.setFont(new Font("MonoSpaced", Font.PLAIN, 12));
details.setEditable(false);
buttons = new Panel(); // Set up the button box
buttons.setLayout(new FlowLayout(FlowLayout.RIGHT, 15, 5));
buttons.setFont(new Font("SansSerif", Font.BOLD, 14));
up = new Button("Up a Directory"); // Set up the two buttons
close = new Button("Close");
up.addActionListener(this);
close.addActionListener(this);
buttons.add(up); // Add buttons to button box
buttons.add(close);
this.add(list, "Center"); // Add stuff to the window
this.add(details, "North");
this.add(buttons, "South");
this.setSize(500, 350);
listDirectory(directory); // And now list the initial directory.
}
/**
* This method uses the list() method to get all entries in a directory
* and then displays them in the List component.
**/
public void listDirectory(String directory) {
// Convert the string to a File object, and check that the dir exists
File dir = new File(directory);
if (!dir.isDirectory())
throw new IllegalArgumentException("FileLister: no such directory");
// Get the (filtered) directory entries
files = dir.list(filter);
// And sort them.
Sorter.sort(files);
// Remove any old entries in the list, and add the new ones
list.removeAll();
list.addItem("[Up to Parent Directory]"); // A special case entry
for(int i = 0; i < files.length; i++) list.addItem(files[i]);
// Display directory name in window titlebar and in the details box
this.setTitle(directory);
details.setText(directory);
// Remember this directory for later.
currentDir = dir;
}
/**
* This ItemListener method uses various File methods to obtain information
* about a file or directory. Then it displays that info in the details box.
**/
public void itemStateChanged(ItemEvent e) {
int i = list.getSelectedIndex() - 1; // minus 1 for Up To Parent entry
if (i < 0) return;
String filename = files[i]; // Get the selected entry
File f = new File(currentDir, filename); // Convert to a File
if (!f.exists()) // Confirm that it exists
throw new IllegalArgumentException("FileLister: " +
"no such file or directory");
// Get the details about the file or directory, concatenate to a string
String info = filename;
if (f.isDirectory()) info += File.separator;
info += " " + f.length() + " bytes ";
info += dateFormatter.format(new java.util.Date(f.lastModified()));
if (f.canRead()) info += " Read";
if (f.canWrite()) info += " Write";
// And display the details string
details.setText(info);
}
/**
* This ActionListener method is invoked when the user double-clicks on an
* entry or clicks on one of the buttons. If they double-click on a file,
* create a FileViewer to display that file. If they double-click on a
* directory, call the listDirectory() method to display that directory
**/
public void actionPerformed(ActionEvent e) {
if (e.getSource() == close) this.dispose();
else if (e.getSource() == up) { up(); }
else if (e.getSource() == list) { // Double click on an item
int i = list.getSelectedIndex(); // Check which item
if (i == 0) up(); // Handle first Up To Parent item
else { // Otherwise, get filename
String name = files[i-1];
File f = new File(currentDir, name); // Convert to a File
String fullname = f.getAbsolutePath();
if (f.isDirectory()) listDirectory(fullname); // List a directory
else new FileViewer(fullname).show(); // or display a file
}
}
}
/** A convenience method to display the contents of the parent directory */
protected void up() {
String parent = currentDir.getParent();
if (parent == null) return;
listDirectory(parent);
}
/** A convenience method used by main() */
public static void usage() {
System.out.println("Usage: java FileLister [directory_name] " +
"[-e file_extension]");
System.exit(0);
}
/**
* A main() method so FileLister can be run standalone.
* Parse command line arguments and create the FileLister object.
* If an extension is specified, create a FilenameFilter for it.
* If no directory is specified, use the current directory.
*/
public static void main(String args[]) throws IOException {
FileLister f;
FilenameFilter filter = null; // The filter, if any
String directory = null; // The specified dir, or the current dir
// Loop through args array, parsing arguments
for(int i = 0; i < args.length; i++) {
if (args[i].equals("-e")) {
if (++i >= args.length) usage();
final String suffix = args[i]; // final for use in anon. class below
// This class is a simple FilenameFilter. It defines the
// accept() method required to determine whether a specified
// file should be listed. A file will be listed if its name
// ends with the specified extension, or if it is a directory.
filter = new FilenameFilter() {
public boolean accept(File dir, String name) {
if (name.endsWith(suffix)) return true;
else return (new File(dir, name)).isDirectory();
}
};
}
else {
if (directory != null) usage(); // If dir already specified, fail.
else directory = args[i];
}
}
// if no directory specified, use the current directoy
if (directory == null) directory = System.getProperty("user.dir");
// Create the FileLister object, with directory and filter specified.
f = new FileLister(directory, filter);
// Arrange for the application to exit when the FileLister window closes
f.addWindowListener(new WindowAdapter() {
public void windowClosed(WindowEvent e) { System.exit(0); }
});
// And pop up the FileLister.
f.show();
}
}
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