gwt - 使用 Tree.Resources 将打开/关闭/叶子图像添加到 gwt 树

Question

我一直在尝试使用 Tree.Resources 来获取 Gwt 树打开状态的图像。以下是我使用的资源类。

public class TreeImageResource implements Tree.Resources
{

    @Override
    public ImageResource treeClosed()
    {
        return ImageResource.IMAGE_RESOURCE.treeClosed();
    }

    @Override
    public ImageResource treeLeaf()
    {
        return ImageResource.IMAGE_RESOURCE.treeLeaf();
    }

    @Override
    public ImageResource treeOpen()
    {
        return ImageResource.IMAGE_RESOURCE.treeOpen();
    }

}

我已经尝试将它传递给带有树的ui的模型和演示者类中的树的构造函数，但它不显示图像。我错过了什么？

我创建了资源客户端包，如下所示

public interface ImageResource extends ClientBundle, ClientBundleWithLookup
{
    ImageResource IMAGE_RESOURCE = GWT.create( ImageResource.class );

        @Source("imageresource/treeClosed.gif")
    ImageResource treeClosed();

    @Source("imageresource/treeLeaf.gif")
    ImageResource treeLeaf();

    @Source("imageresource/treeOpen.gif")
    ImageResource treeOpen();
}

树的创建如下

public class MainPanel extends Composite implements Display
{

  private static MainPanelUiBinder uiBinder = GWT.create(MainPanelUiBinder.class );

  @UiField
  SimplePanel desktopPanel;
  @UiField
  ListBox recentToolsBox;
  @UiField
  Tree recentToolsTree;

  interface MainPanelUiBinder extends UiBinder<Widget, ToolsMainPanel>
  {
  }

  public MainPanel()
  {
    Tree.Resources resources = new TreeImageResource();
    recentToolsTree = new Tree(resources);
    initWidget( uiBinder.createAndBindUi( this) );
    recentToolsTree.setAnimationEnabled( true );
  }
}