public class Menu {
  // 菜單id
  private String id;
  // 菜單名稱
  private String name;
  // 父菜單id
  private String parentId;
  // 菜單url
  private String url;
  // 菜單圖標(biāo)
  private String icon;
  // 菜單順序
  private int order;
  // 子菜單
  private List children;
  // ... 省去getter和setter方法以及toString方法
}

　/*
   * 排序,根據(jù)order排序
   */
  public Comparator order(){
    Comparator comparator = new Comparator() {
      @Override
      public int compare(Menu o1, Menu o2) {
        if(o1.getOrder() != o2.getOrder()){
          return o1.getOrder() - o2.getOrder();
        }
        return 0;
      }
    };
    return comparator;
  }

public Map findTree(){
  Map data = new HashMap();
    try {//查詢所有菜單
      List allMenu = menuDao.findTree();
      //根節(jié)點(diǎn)
      List rootMenu = new ArrayList();
      for (Menu nav : allMenu) {
        if(nav.getParentId().equals("0")){//父節(jié)點(diǎn)是0的，為根節(jié)點(diǎn)。
          rootMenu.add(nav);
        }
      }
      /* 根據(jù)Menu類的order排序 */
      Collections.sort(rootMenu, order());
      //為根菜單設(shè)置子菜單，getClild是遞歸調(diào)用的
      for (Menu nav : rootMenu) {
        /* 獲取根節(jié)點(diǎn)下的所有子節(jié)點(diǎn) 使用getChild方法*/
        List childList = getChild(nav.getId(), allMenu);
        nav.setChildren(childList);//給根節(jié)點(diǎn)設(shè)置子節(jié)點(diǎn)
      }
      /**
       * 輸出構(gòu)建好的菜單數(shù)據(jù)。
       * 
       */
      data.put("success", "true");
      data.put("list", rootMenu);
      return data;
    } catch (Exception e) {
      data.put("success", "false");
      data.put("list", new ArrayList());
      return data;
    }
  }

/**
   * 獲取子節(jié)點(diǎn)
   * @param id 父節(jié)點(diǎn)id
   * @param allMenu 所有菜單列表
   * @return 每個(gè)根節(jié)點(diǎn)下，所有子菜單列表
   */
  public List getChild(String id,List allMenu){
    //子菜單
    List childList = new ArrayList();
    for (Menu nav : allMenu) {
      // 遍歷所有節(jié)點(diǎn)，將所有菜單的父id與傳過來的根節(jié)點(diǎn)的id比較
      //相等說明：為該根節(jié)點(diǎn)的子節(jié)點(diǎn)。
      if(nav.ParentId().equals(id)){
        childList.add(nav);
      }
    }
    //遞歸
    for (Menu nav : childList) {
      nav.setChildren(getChild(nav.getId(), allMenu));
    }
    Collections.sort(childList,order());//排序
    //如果節(jié)點(diǎn)下沒有子節(jié)點(diǎn)，返回一個(gè)空List（遞歸退出）
    if(childList.size() == 0){
      return new ArrayList();
    }
    return childList;
  }

{
 "success": "true",
 "list": [
   {
    "id": "1",
    "name": "Java",
    "parentid": "0",
    "url": "http://www.aliouchen.com",
    "order": 1,
    "children": [
     {
       "id": "2",
       "name": "并發(fā)編程",
       "parentid": "1",
       "url": "http://www.aliouchen.com",
       "order": 1,
       "children": []
     },
     {
       "id": "3",
       "name": "多線程",
       "parentid": "1",
       "url": "http://www.aliouchen.com",
       "order": 2,
       "children": [
         "id": "4",
         "name": "Thread",
         "parentid": "3",
         "url": "http://www.aliouchen.com",
         "order": 1,
　　　　　　　　　　"children":[]
       ]
     }
    ]
   },
   {
    "id": "5",
    "name": "Python",
    "parentid": "0",
    "url": "http://www.aliouchen.com",
    "order": 2,
    "children": []
   }
  ]
}