<div id="categoryChooseDiv" title="请选择分类"
      style="width: 650px; height: 300px;">
       <ul id="MyTree"></ul>
  </div>

  function showCategory(){
      $('#MyTree').tree({  
         checkbox: false,  
         url: '/category/getCategorys.java?Id=0',  
         onBeforeExpand:function(node,param){ 
           $('#MyTree').tree('options').url = "/category/getCategorys.java?Id=" + node.id;
         },        
        onClick:function(node){
          var state=node.state;
           if(!state){                  //判断当前选中的节点是否为根节点
             currentId=node.id;
            $("#chooseOk").attr( "disabled" , false );  //如果为根节点 则OK按钮可用
            }else{
            $("#chooseOk").attr( "disabled" , true );  //如果不为根节点 则OK按钮不可用
            }
          } 
      });
  }

      var nodes=[];      //定义数组用来存放各个节点名称
      var node =$("#MyTree").tree("getSelected"); //当前选中节点
      nodes.push(node.text);            //首先放入当前节点
      var pnode = $('#MyTree').tree('getParent',node.target); //获取当前节点的父节点
      while(pnode!=null){
        nodes.push(pnode.text);          //依次放入各个父节点，直到根节点为止
        pnode = $('#MyTree').tree('getParent',pnode.target);
      }
      nodes.reverse();             //数组元素倒序排序
      $.each(nodes,function(){        //循环取值
        var html=this;
          $("#inCategoryDiv").html( $("#inCategoryDiv").html() + html + ">>" );
      }); 

 public ResponseEntity<String> findBy(Integer Id ) {
    List<Category> categorys = getcategorys(Id );
    String ss="";
    ss+="[";
    for( Category category : categorys )
       {
       ss+="{";
       //ss += "\"id\": \""+category.getId()+"\",\"text\": \""+category.getName().toString()+"\",\"iconCls\": \"icon-ok\",\"state\": \"closed\"";;
       List<Category> cs = getcategorys( category.getId() );  //判断当前节点是否还有子节点
       if(cs.size()==0){ //没有子节点 设置 state 为空
       ss+=String.format("\"id\": \"%s\", \"text\": \"%s\", \"iconCls\": \"\", \"state\": \"\"", category.getId() , category.getName());
       }else{    // 还有子节点 设置 state为closed
       ss+=String.format("\"id\": \"%s\", \"text\": \"%s\", \"iconCls\": \"\", \"state\": \"closed\"", category.getId() , category.getName());
      }
       ss+="},";
       }
       ss=ss.substring(0, ss.length() - 1); 
       ss+="]";
      return super.responseString(ss); //字符编码转换
    }