undoabletreeedit.java

来自「《深入浅出设计模式》的完整源代码」· Java 代码 · 共 91 行

package taxonomy;

import javax.swing.event.TreeModelEvent;
import javax.swing.undo.*;

/**
  A class whose instances represent undoable edits to a tree
  @see TaxTreeModel
  @see Node
  @see <u>Java Swing</u> pp 647
*/
public class UndoableTreeEdit extends AbstractUndoableEdit {

  /**
    The tree model on which this edit was made
  */
  private TaxTreeModel tm;

  /**
    The tree model event generated by this edit
  */
  private TreeModelEvent tme;

  /**
    The parent element in the tree affected by this edit
  */
  private Object parent;

  /**
    The new child element added to the tree by this edit
  */
  private Object child;

  /**
    Construct a new undoable tree edit.
    @param aTM The tree model on which this edit was made
    @param aTME The tree model event generated by this edit
    @param pVal The parent element in the tree affected by this edit
    @param cVal The new child element added to the tree by this edit
  */
  public UndoableTreeEdit(TaxTreeModel aTM,
                          TreeModelEvent aTME,
                          Object pVal, Object cVal) {
    tm = aTM;
    tme = aTME;
    parent = pVal;
    child = cVal;
  }

  /**
    Return a reasonable/descriptive name for this edit.
    @return A string representation for this edit
  */
  public String getPresentationName() {
    return ("added " + child.toString() + " to " + parent.toString());
  }

  /**
    Redo this edit.
  */
  public void redo() throws CannotRedoException {
    // call redo in the super class
    // to ensure this edit is in the appropriate state
    super.redo();

    // reinsert the element into the tree
    // build a new tree model event capturing the insertion
    // notify any listeners in the table model
    ((Node)tm.find(parent)).addChild(child);
    TreeModelEvent e = tm.buildTreeModelEvent(tm.find(parent));
    tme = e;
    tm.notifyTreeModelListeners(e);
  }

  /**
    Undo this edit.
  */
  public void undo() throws CannotUndoException {
    // call undo in the super class
    // to ensure this edit is in the appropriate state
    super.undo();

    // remove the (child) element from the tree
    // notify any listeners in the table model
    tm.find(parent).removeChild(tm.find(child));
    //TreeModelEvent e = new TreeModelEvent((tm.find(parent));
    //tme = e;
    tm.notifyTreeModelListeners(tme);
  }
}