JFace 的treeViewer的雙擊展開或收縮

treeViewer.addDoubleClickListener(new IDoubleClickListener() {
	
	@Override
	public void doubleClick(DoubleClickEvent event) {
		
		IStructuredSelection is = (IStructuredSelection)event.getSelection();
		Object obj = is.getFirstElement();
		//自定義的節點對象
		Node node = (Node)obj;
		TreeItem[] items = treeViewer.getTree().getSelection();
		 
			if(null == items || items.length == 0){
				return;
			}
			if(items[0].getExpanded()){
				items[0].setExpanded(false);
			}else{
			 
				//從選中的節點處展開
				treeViewer.expandToLevel(node, 1);
			}
		 
		
	}
});