if(node.getParent()==null ||
StringUtil.clean(node.getParent().getIdentity())==null ){
node.setParent( db_tree.getRoot() );
}else{
Node parent = nodeDao.read(node.getParent());
if( parent == null )
throw new ApplicationException("父结点(id="
+node.getParent().getIdentity()+")已不存在!");
}