easyui treegrid 异步加载树

$('#material').treegrid({
    nowrap: false,
    rownumbers: true,
    animate:true,
    collapsible:true,
    loadMsg:'数据加载中请稍后……',
    url:'<c:url value="/jxc/sysinfo/loadMaterialTree.jsps"/>',
    idField:'matCode',
    treeField:'matCode',
    frozenColumns:[[
                 {title:'料号',field:'matCode',width:180}
    ]],
    columns:[[
     {field:'matType',title:'产品类型',width:120},
     {field:'matShow',title:'产品名称',width:120},
     {field:'matStandard',title:'产品规格',width:120},
     {field:'matProperties',title:'产品属性',width:120}
    ]],
    onBeforeLoad:function(row,param){

     // 此处就是异步加载地所在
     if (row){
      $(this).treegrid('options').url = '<c:url value="/jxc/sysinfo/loadMaterialTree.jsps"/>?matParentId='+row.matId;
     } else {
      $(this).treegrid('options').url = '<c:url value="/jxc/sysinfo/loadMaterialTree.jsps?matName="/>';
     }
    },
    onClickRow:function(){
     /**
     ** 如果是新建或者修改，以及删除，则清除查询form表单数据 
     **/
     $('#materialSearch').form('clear');
    }
   });

<table id="material"></table>

以及树的异步添加、删除、刷新等

请参考: http://jquery-easyui.wikidot.com/document:treegrid