如何使EMF模型对应的编辑控件能处理Undo&Redo操作

在EMF自动生成的editor中,只提供了TreeViewer作为编辑控件,自动生成的代码能让TreeViewer处理Redo&Undo操作,如果还需要对EMF对应的Attribute使用Text, Combo等Widget进行编辑的话,那么如何将这些Widget的编辑也能实现Undo&Redo操作呢?

首先我们来分析一下,对于TreeViewer是如何实现Redo&Undo操作的,在生成的editor代码中有类似这样的一句(这个是我改写后的,实际生成的可能有所区别):为了只针对Redo&Undo对UI进行更新,还需要对RedoAction和UndoAction做进一步处理:
其做法就是要让editor知道当前的Action,然后在修改UI的时候,取得该Action看是否是我们指定的Action(RedoAction&UndoAction).

java 代码

viewer.setContentProvider(new AdapterFactoryContentProvider(
                getAdapterFactory()));

AdapterFactoryContentProvider实现了INotifyChangedListener接口,该接口就是用来处理在EMF模型发生变动时,如何更新绑定的UI控件:

java 代码

public void notifyChanged(Notification notification)
  {
    if (viewer != null && viewer.getControl() != null && !viewer.getControl().isDisposed())
    {
      // If the notification is an IViewerNotification, it specifies how ViewerRefresh should behave.  Otherwise fall
      // back to NotifyChangedToViewerRefresh, which determines how to refresh the viewer directly from the model
      // notification.
      //
      if (notification instanceof IViewerNotification)
      {
        if (viewerRefresh == null)
        {
          viewerRefresh = new ViewerRefresh(viewer);
        }

        if (viewerRefresh.addNotification((IViewerNotification)notification))
        {
          viewer.getControl().getDisplay().asyncExec(viewerRefresh);
        }
      }
      else
      {
        NotifyChangedToViewerRefresh.handleNotifyChanged(
          viewer,
          notification.getNotifier(),
          notification.getEventType(),
          notification.getFeature(),
          notification.getOldValue(),
          notification.getNewValue(),
          notification.getPosition());
      }
    }
  }

再看代码:

java 代码

public AdapterFactoryContentProvider(AdapterFactory adapterFactory)
  {
    this.adapterFactory = adapterFactory;

    if (adapterFactory instanceof IChangeNotifier)
    {
      ((IChangeNotifier)adapterFactory).addListener(this);
    }
  }

这里关键的一句就是:

java 代码

((IChangeNotifier)adapterFactory).addListener(this);

它将更新UI的通知操作与adapterFactory关联起来,然后在EMF模型发生变动的时候,会从adapterFactory来找到所有注册的INotifyChangedListener
因此做法就相当简单了,即将EMF模型对应的编辑控件实现INotifyChangedListener接口,然后拿到adapterFactory,并把该控件注册进去.
下面我的一个实现:
AbstractDoradoSection包含了EMF模型当前节点属性的对应编辑控件集合,让其实现INotifyChangedListener接口

并在构造函数中注册到adapterFactory中:

java 代码

public AbstractDoradoSection(IAdaptable adaptable, Object input,
            Composite parent, String title, int style) {
        this.adaptable = adaptable;
        this.input = input;
        this.title = title;
        this.style = ExpandableComposite.TITLE_BAR | style;

        AdapterFactory adapterFactory = (AdapterFactory) adaptable
                .getAdapter(AdapterFactory.class);
        ((IChangeNotifier) adapterFactory).addListener(this);

        initialize(parent);
    }

Redo&Undo更新UI处理:

java 代码

/**
 * 当emf模型发生变化之后,更新ui,主要针对redo和undo处理
 *
 * @see org.eclipse.emf.edit.provider.INotifyChangedListener#notifyChanged(org.eclipse.emf.common.notify.Notification)
 */
public void notifyChanged(final Notification notification) {
    IActionProvider actionProvider = (IActionProvider) adaptable
            .getAdapter(IActionProvider.class);
    if (actionProvider.getAction() instanceof NotifierAction) {
        Object feature = notification.getFeature();
        if (feature instanceof EAttribute && rows != null) {
            for (Iterator iter = rows.iterator(); iter.hasNext();) {
                final AttributeRow row = (AttributeRow) iter.next();
                if (row.getAttribute() == feature) {
                    row.setTextContent(notification.getNewStringValue(), true);
                    break;
                }
            }
        }
    }
}