undomanagerhelper.java

The Definitive Guide to Java Swing, Third Edition by John Zukowski (Author) 源码

import javax.swing.*;
import javax.swing.undo.*;
import java.awt.*;
import java.awt.event.*;

public class UndoManagerHelper {

  public static Action getUndoAction(UndoManager manager, String label) {
    return new UndoAction(manager, label);
  }
  public static Action getUndoAction(UndoManager manager) {
    return new UndoAction(manager, (String)UIManager.get("AbstractUndoableEdit.undoText"));
  }
  public static Action getRedoAction(UndoManager manager, String label) {
    return new RedoAction(manager, label);
  }
  public static Action getRedoAction(UndoManager manager) {
    return new RedoAction(manager, (String)UIManager.get("AbstractUndoableEdit.redoText"));
  }

  private abstract static class UndoRedoAction extends AbstractAction {
    UndoManager undoManager = new UndoManager();
    String errorMessage = "Cannot undo";
    String errorTitle = "Undo Problem";
    protected UndoRedoAction(UndoManager manager, String name) {
      super(name);
      undoManager = manager;
    }
    public void setErrorMessage(String newValue) {
      errorMessage = newValue;
    }
    public void setErrorTitle(String newValue) {
      errorTitle = newValue;
    }
    protected void showMessage(Object source) {
      if (source instanceof Component) {
        JOptionPane.showMessageDialog((Component)source, errorMessage, errorTitle, JOptionPane.WARNING_MESSAGE);
      } else {
        System.err.println(errorMessage);
      }
    }
  }

  public static class UndoAction extends UndoRedoAction {
    public UndoAction(UndoManager manager, String name) {
      super(manager, name);
      setErrorMessage("Cannot undo");
      setErrorTitle("Undo Problem");
    }
    public void actionPerformed(ActionEvent actionEvent) {
      try {
        undoManager.undo();
      } catch (CannotUndoException cannotUndoException) {
        showMessage(actionEvent.getSource());
      }
    }
  }

  public static class RedoAction extends UndoRedoAction {
    public RedoAction(UndoManager manager, String name) {
      super(manager, name);
      setErrorMessage("Cannot redo");
      setErrorTitle("Redo Problem");
    }
    public void actionPerformed(ActionEvent actionEvent) {
      try {
        undoManager.redo();
      } catch (CannotRedoException cannotRedoException) {
        showMessage(actionEvent.getSource());
      }
    }
  }
}