@RequestMapping(value = "/tree")  public void tree(HttpServletRequest request, HttpServletResponse response) throws IOException {   this.writeJson(response, bookService.getTree());  }

 /**   * 获取树   */  @Override  public List<Tree> getTree(){   try {    List<Tree> trees = new ArrayList<Tree>();    List<TBookType> root = this.search(0);    if(root != null && root.size() > 0){     for(TBookType tb : root){      Tree rootnode = this.getNode(tb);      rootnode.setState("open");      trees.add(rootnode);     }    }    return trees;   } catch (Exception e) {    e.printStackTrace();    return null;   }  }  /**   * 递归   */  private Tree getNode(TBookType node){   if(node == null){    return null;   }   try {    Tree treenode = new Tree();    treenode.setId(String.valueOf(node.getId()));    treenode.setText(node.getName());    treenode.setPid(String.valueOf(node.getPid()));    List<TBookType> children = this.search(node.getId());    if(children != null && children.size() > 0){     treenode.setState("closed");     for(TBookType child : children){      Tree childnode = this.getNode(child);      if(childnode != null){       treenode.getChildren().add(childnode);//递归      }     }    }    return treenode;   } catch (Exception e) {    throw new BusinessException("获取数据出错!", e);   }  }