filechooserdemo.java

一个小公司要求给写的很简单的任务管理系统。

	int retval = chooser.showDialog(frame, null);
	if (retval == APPROVE_OPTION) {
	    JOptionPane.showMessageDialog(frame, getResultString());
	} else if (retval == CANCEL_OPTION) {
	    JOptionPane.showMessageDialog(frame, "User cancelled operation. No file was chosen.");
	} else if (retval == ERROR_OPTION) {
	    JOptionPane.showMessageDialog(frame, "An error occured. No file was chosen.");
	} else {
	    JOptionPane.showMessageDialog(frame, "Unknown operation occured.");
	}
    }

    private void resetFileFilters(boolean enableFilters,
                                  boolean showExtensionInDescription) {
        chooser.resetChoosableFileFilters();
        if (enableFilters) {
            jpgFilter = createFileFilter("JPEG Compressed Image Files",
                                         showExtensionInDescription, "jpg");
            gifFilter = createFileFilter("GIF Image Files",
                                         showExtensionInDescription, "gif");
            bothFilter = createFileFilter("JPEG and GIF Image Files",
                                          showExtensionInDescription, "jpg",
                                          "gif");
            chooser.addChoosableFileFilter(bothFilter);
            chooser.addChoosableFileFilter(jpgFilter);
            chooser.addChoosableFileFilter(gifFilter);
        }
    }

    private FileFilter createFileFilter(String description,
            boolean showExtensionInDescription, String...extensions) {
        if (showExtensionInDescription) {
            description = createFileNameFilterDescriptionFromExtensions(
                    description, extensions);
        }
        return new FileNameExtensionFilter(description, extensions);
    }

    private String createFileNameFilterDescriptionFromExtensions(
            String description, String[] extensions) {
        String fullDescription = (description == null) ?
                "(" : description + " (";
        // build the description from the extension list
        fullDescription += "." + extensions[0];
        for (int i = 1; i < extensions.length; i++) {
            fullDescription += ", .";
            fullDescription += extensions[i];
        }
        fullDescription += ")";
        return fullDescription;
    }

    class WizardDialog extends JDialog implements ActionListener {
	CardLayout cardLayout;
	JPanel cardPanel;
	JLabel messageLabel;
	JButton backButton, nextButton, closeButton;

	WizardDialog(JFrame frame, boolean modal) {
	    super(frame, "Embedded JFileChooser Demo", modal);

	    cardLayout = new CardLayout();
	    cardPanel = new JPanel(cardLayout);
	    getContentPane().add(cardPanel, BorderLayout.CENTER);

	    messageLabel = new JLabel("", JLabel.CENTER);
	    cardPanel.add(chooser, "fileChooser");
	    cardPanel.add(messageLabel, "label");
	    cardLayout.show(cardPanel, "fileChooser");
	    chooser.addActionListener(this);

	    JPanel buttonPanel = new JPanel();
	    backButton = new JButton("< Back");
	    nextButton = new JButton("Next >");
	    closeButton = new JButton("Close");

	    buttonPanel.add(backButton);
	    buttonPanel.add(nextButton);
	    buttonPanel.add(closeButton);

	    getContentPane().add(buttonPanel, BorderLayout.SOUTH);

	    backButton.setEnabled(false);
	    getRootPane().setDefaultButton(nextButton);

	    backButton.addActionListener(this);
	    nextButton.addActionListener(this);
	    closeButton.addActionListener(this);

	    pack();
	    setLocationRelativeTo(frame);
	}

	public void actionPerformed(ActionEvent evt) {
	    Object src = evt.getSource();
	    String cmd = evt.getActionCommand();

	    if (src == backButton) {
		back();
	    } else if (src == nextButton) {
		FileChooserUI ui = chooser.getUI();
		if (ui instanceof BasicFileChooserUI) {
		    // Workaround for bug 4528663. This is necessary to
		    // pick up the contents of the file chooser text field.
		    // This will trigger an APPROVE_SELECTION action.
		    ((BasicFileChooserUI)ui).getApproveSelectionAction().actionPerformed(null);
		} else {
		    next();
		}
	    } else if (src == closeButton) {
		close();
	    } else if (cmd == APPROVE_SELECTION) {
		next();
	    } else if (cmd == CANCEL_SELECTION) {
		close();
	    }
	}

	private void back() {
	    backButton.setEnabled(false);
	    nextButton.setEnabled(true);
	    cardLayout.show(cardPanel, "fileChooser");
	    getRootPane().setDefaultButton(nextButton);
	    chooser.requestFocus();
	}

	private void next() {
	    backButton.setEnabled(true);
	    nextButton.setEnabled(false);
	    messageLabel.setText(getResultString());
	    cardLayout.show(cardPanel, "label");
	    getRootPane().setDefaultButton(closeButton);
	    closeButton.requestFocus();
	}

	private void close() {
	    setVisible(false);
	}

	public void dispose() {
	    chooser.removeActionListener(this);
	    
	    // The chooser is hidden by CardLayout on remove
	    // so fix it here
	    cardPanel.remove(chooser);
	    chooser.setVisible(true);

	    super.dispose();
	}
    }

    private String getResultString() {
	String resultString = null;
	String filter = chooser.getFileFilter().getDescription();
	String path = null;
	boolean isDirMode = (chooser.getFileSelectionMode() == DIRECTORIES_ONLY);
	boolean isMulti = chooser.isMultiSelectionEnabled();

	if (isMulti) {
	    File [] files = chooser.getSelectedFiles();
	    if (files != null && files.length > 0) {
		path = "";
		for (int i = 0; i < files.length; i++) {
		    path = path + "<br>" + files[i].getPath();
		}
	    }
	} else {
	    File file = chooser.getSelectedFile();
	    if (file != null) {
		path = "<br>" + file.getPath();
	    }
	}
	if (path != null) {
	    path = path.replace(" ", "&nbsp;");
	    filter = filter.replace(" ", "&nbsp;");
	    resultString =
		"<html>You chose " + (isMulti ? "these" : "this") + " " +
		(isDirMode ? (isMulti ? "directories" : "directory")
			   : (isMulti ? "files" : "file")) +
		": <code>" + path +
		"</code><br><br>with filter: <br><code>" + filter;
	} else {
	    resultString = "Nothing was chosen";
	}
	return resultString;
    }




    /** An ActionListener that listens to the radio buttons. */
    class OptionListener implements ActionListener {
	public void actionPerformed(ActionEvent e) {
	    JComponent c = (JComponent) e.getSource();
	    boolean selected = false;
	    if (c instanceof JToggleButton) {
		selected = ((JToggleButton)c).isSelected();
	    }

	    if (c == openRadioButton) {
		chooser.setDialogType(OPEN_DIALOG);
		customField.setEnabled(false);
		repaint();
	    } else if (c == useEmbedInWizardCheckBox) {
		useControlsCheckBox.setEnabled(!selected);
		useControlsCheckBox.setSelected(!selected);
		chooser.setControlButtonsAreShown(!selected);
	    } else if (c == useControlsCheckBox) {
		chooser.setControlButtonsAreShown(selected);
            } else if (c == enableDragCheckBox) {
                chooser.setDragEnabled(selected);
	    } else if (c == saveRadioButton) {
		chooser.setDialogType(SAVE_DIALOG);
		customField.setEnabled(false);
		repaint();
	    } else if (c == customButton || c == customField) {
		customField.setEnabled(true);
		chooser.setDialogType(CUSTOM_DIALOG);		
		repaint();
            } else if (c == showAllFilesFilterCheckBox) {
                chooser.setAcceptAllFileFilterUsed(selected);
            } else if (c == showImageFilesFilterCheckBox) {
                resetFileFilters(selected,
                                 showFullDescriptionCheckBox.isSelected());
                showFullDescriptionCheckBox.setEnabled(selected);
	    } else if (c == setHiddenCheckBox) {
		chooser.setFileHidingEnabled(!selected);
	    } else if (c == accessoryCheckBox) {
		if (selected) {
		    chooser.setAccessory(previewer);
		} else {
		    chooser.setAccessory(null);
		}
	    } else if (c == useFileViewCheckBox) {
		if (selected) {
		    chooser.setFileView(fileView);
		} else {
		    chooser.setFileView(null);
		}
	    } else if (c == showFullDescriptionCheckBox) {
                resetFileFilters(showImageFilesFilterCheckBox.isSelected(),
                                 selected);
	    } else if (c == justFilesRadioButton) {
		chooser.setFileSelectionMode(FILES_ONLY);
	    } else if (c == justDirectoriesRadioButton) {
		chooser.setFileSelectionMode(DIRECTORIES_ONLY);
	    } else if (c == bothFilesAndDirectoriesRadioButton) {
		chooser.setFileSelectionMode(FILES_AND_DIRECTORIES);
	    } else if (c == singleSelectionRadioButton) {
		if (selected) {
		    chooser.setMultiSelectionEnabled(false);
		} 
	    } else if (c == multiSelectionRadioButton) {
		if (selected) {
		    chooser.setMultiSelectionEnabled(true);
		} 
	    } else if (c == lafComboBox) {
		SupportedLaF supportedLaF = ((SupportedLaF)lafComboBox.getSelectedItem());
		LookAndFeel laf = supportedLaF.laf;
		try {
		    UIManager.setLookAndFeel(laf);
		    SwingUtilities.updateComponentTreeUI(frame);
		    if(chooser != null) {
			SwingUtilities.updateComponentTreeUI(chooser);
		    }
		    frame.pack();
		} catch (UnsupportedLookAndFeelException exc) {
		    // This should not happen because we already checked
		    ((DefaultComboBoxModel)lafComboBox.getModel()).removeElement(supportedLaF);
		}
	    }

	}
    }

    class FilePreviewer extends JComponent implements PropertyChangeListener {
	ImageIcon thumbnail = null;

	public FilePreviewer(JFileChooser fc) {
	    setPreferredSize(new Dimension(100, 50));
	    fc.addPropertyChangeListener(this);
	}

	public void loadImage(File f) {
            if (f == null) {
                thumbnail = null;
            } else {
		ImageIcon tmpIcon = new ImageIcon(f.getPath());
		if(tmpIcon.getIconWidth() > 90) {
		    thumbnail = new ImageIcon(
			tmpIcon.getImage().getScaledInstance(90, -1, Image.SCALE_DEFAULT));
		} else {
		    thumbnail = tmpIcon;
		}
	    }
	}

	public void propertyChange(PropertyChangeEvent e) {
	    String prop = e.getPropertyName();
	    if (prop == SELECTED_FILE_CHANGED_PROPERTY) {
		if(isShowing()) {
                    loadImage((File) e.getNewValue());
		    repaint();
		}
	    }
	}

	public void paint(Graphics g) {
	    if(thumbnail != null) {
		int x = getWidth()/2 - thumbnail.getIconWidth()/2;
		int y = getHeight()/2 - thumbnail.getIconHeight()/2;
		if(y < 0) {
		    y = 0;
		}

		if(x < 5) {
		    x = 5;
		}
		thumbnail.paintIcon(this, g, x, y);
	    }
	}
    }

    public static void main(String s[]) {
	/*
	   NOTE: By default, the look and feel will be set to the
	   Cross Platform Look and Feel (which is currently Metal).
	   The user may someday be able to override the default
	   via a system property. If you as the developer want to
	   be sure that a particular L&F is set, you can do so
	   by calling UIManager.setLookAndFeel(). For example, the
	   first code snippet below forcibly sets the UI to be the
	   System Look and Feel. The second code snippet forcibly
	   sets the look and feel to the Cross Platform L&F.

	   Snippet 1:
	   try {
	      UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
	   } catch (Exception exc) {
	      System.err.println("Error loading L&F: " + exc);
	   }

	   Snippet 2:
	   try {
	      UIManager.setLookAndFeel(UIManager.getCrossPlatformLookAndFeelClassName());
	   } catch (Exception exc) {
	      System.err.println("Error loading L&F: " + exc);
	   }
	*/

	FileChooserDemo panel = new FileChooserDemo();

	frame = new JFrame("FileChooserDemo");
	frame.addWindowListener(new WindowAdapter() {
	    public void windowClosing(WindowEvent e) {System.exit(0);}
	});
	frame.getContentPane().add("Center", panel);
	frame.pack();
	frame.setVisible(true);
    }

    class InsetPanel extends JPanel {
	Insets i;
	InsetPanel(Insets i) {
	    this.i = i;
	}
	public Insets getInsets() {
	    return i;
	}
    }

    /**
     * A utility function that layers on top of the LookAndFeel's
     * isSupportedLookAndFeel() method. Returns true if the LookAndFeel
     * is supported. Returns false if the LookAndFeel is not supported
     * and/or if there is any kind of error checking if the LookAndFeel
     * is supported.
     *
     * The L&F menu will use this method to detemine whether the various
     * L&F options should be active or inactive.
     *
     */
     protected boolean isAvailableLookAndFeel(String laf) {
         try { 
             Class lnfClass = Class.forName(laf);
             LookAndFeel newLAF = (LookAndFeel)(lnfClass.newInstance());
             return newLAF.isSupportedLookAndFeel();
         } catch (Exception e) { // If ANYTHING weird happens, return false
             return false;
         }
     }
}