import com.intellij.ide.dnd.DnDDragStartBean; //导入依赖的package包/类
@SuppressWarnings("unchecked")
@Nullable
private File extractDropFile(@Nonnull final DropTargetDropEvent dtde) throws Exception {
  try {
    java.util.List<File> files = null;
    final Object objectToDrop = dtde.getTransferable().getTransferData(DataFlavor.javaFileListFlavor);
    if (objectToDrop instanceof DnDDragStartBean) {
      final Object wrapper = ((DnDDragStartBean) objectToDrop).getAttachedObject();
      if (wrapper instanceof TransferableWrapper) {
        files = ((TransferableWrapper) wrapper).asFileList();
      }
    } else if (objectToDrop instanceof java.util.List) {
      files = (java.util.List<File>) objectToDrop;
    }

    return files == null || files.isEmpty() ? null : files.get(0);
  } catch (UnsupportedFlavorException ex) {
    return null;
  }
}
 

import com.intellij.ide.dnd.DnDDragStartBean; //导入依赖的package包/类
private void installDnD(final int index, NavBarItem component) {
  DnDSupport.createBuilder(component).setBeanProvider(dnDActionInfo -> new DnDDragStartBean(new TransferableWrapper() {
    @Override
    public List<File> asFileList() {
      Object o = myModel.get(index);
      if (o instanceof PsiElement) {
        VirtualFile vf = o instanceof PsiDirectory ? ((PsiDirectory)o).getVirtualFile() : ((PsiElement)o).getContainingFile().getVirtualFile();
        if (vf != null) {
          return Collections.singletonList(new File(vf.getPath()).getAbsoluteFile());
        }
      }
      return Collections.emptyList();
    }

    @Override
    public TreeNode[] getTreeNodes() {
      return null;
    }

    @Override
    public PsiElement[] getPsiElements() {
      return null;
    }
  })).setDisposableParent(component).install();
}
 

import com.intellij.ide.dnd.DnDDragStartBean; //导入依赖的package包/类
private void installDnD(final int index, NavBarItem component) {
  DnDSupport.createBuilder(component)
    .setBeanProvider(new Function<DnDActionInfo, DnDDragStartBean>() {
      @Override
      public DnDDragStartBean fun(DnDActionInfo dnDActionInfo) {
        return new DnDDragStartBean(new TransferableWrapper() {
          @Override
          public List<File> asFileList() {
            final Object o = myModel.get(index);
            if (o instanceof PsiElement) {
              final VirtualFile vf =  o instanceof PsiDirectory ? ((PsiDirectory)o).getVirtualFile()
                                                                : ((PsiElement)o).getContainingFile().getVirtualFile();
              if (vf != null) {
                return Arrays.asList(new File(vf.getPath()).getAbsoluteFile());
              }
            }
            return Collections.emptyList();
          }

          @Override
          public TreeNode[] getTreeNodes() {
            return null;
          }

          @Override
          public PsiElement[] getPsiElements() {
            return null;
          }
        });
      }
    })
    .setDisposableParent(component)
    .install();
}
 

import com.intellij.ide.dnd.DnDDragStartBean; //导入依赖的package包/类
@Override
public DnDDragStartBean startDragging(DnDAction action, Point dragOrigin)
{
	int index = locationToIndex(dragOrigin);
	if(index < 0)
	{
		return null;
	}
	return myGroup.getItems()[index].startDragging();
}
 

import com.intellij.ide.dnd.DnDDragStartBean; //导入依赖的package包/类
@Override
public DnDDragStartBean startDragging(DnDAction action, Point dragOrigin) {
  return new DnDDragStartBean(new LayoutNodesDraggingObject(myArtifactsEditor, getNodesToDrag()));
}
 

import com.intellij.ide.dnd.DnDDragStartBean; //导入依赖的package包/类
@Override
public DnDDragStartBean startDragging(DnDAction action, Point dragOrigin) {
  List<PackagingSourceItem> items = getSelectedItems();
  return new DnDDragStartBean(new SourceItemsDraggingObject(items.toArray(new PackagingSourceItem[items.size()])));
}
 

import com.intellij.ide.dnd.DnDDragStartBean; //导入依赖的package包/类
@Override
public DnDDragStartBean startDragging(final DnDAction action, final Point dragOrigin) {
  return new DnDDragStartBean(getNodesToDrag());
}
 

import com.intellij.ide.dnd.DnDDragStartBean; //导入依赖的package包/类
@Nullable public DnDDragStartBean startDragging() {
  if (isAnyComponent()) return null;
  return new DnDDragStartBean(this);
}
 

import com.intellij.ide.dnd.DnDDragStartBean; //导入依赖的package包/类
public DnDDragStartBean startDragging(final DnDAction action, final Point dragOrigin) {
  return new DnDDragStartBean(getNodesToDrag());
}
 

import com.intellij.ide.dnd.DnDDragStartBean; //导入依赖的package包/类
public DnDDragStartBean startDragging(DnDAction action, Point dragOrigin)
{
	return new DnDDragStartBean(new MyDragBean(myIsRow, getSelectedCells(dragOrigin)));
}
 

import com.intellij.ide.dnd.DnDDragStartBean; //导入依赖的package包/类
/**
 * Processes dragging the item.
 *
 * @return the drag start bean for the drag process, or null if the item cannot be dragged.
 */
@Nullable DnDDragStartBean startDragging();