Extjs的 gridpanel 中ddGroup是干嘛用的?答:proxy: new Ext.data.HttpProxy({url:'loadUserallRole.action'}),reader: new Ext.data.JsonReader({ totalProperty: 'totalProperty',root: 'role'}, [{name : 'id',mapping:'id',type : 'string'},{name : 'uname',mapping:'uname',type : 'string'},{name : 'fcd',mapping:'fcd'...