extjs组建化编程（GridPanel分页json的）

JsonPagingGridPanel =Ext.extend(Ext.grid.GridPanel,{        constructor:function(){     this["store"]:new Ext.data.Store({         url:"",      //reader解析      reader:new Ext.data.JsonReader({         //autoLoad:true,               root:"rows",//解析指定xml的节点         //分页需要的属性（数量）         totalProperty:"count"         },Ext.data.Record.create(["id","type","money"])         )         });     JsonPagingGridPanel.superclass.constructor.call(this,{    renderTo:Ext.getBody(),    width:300,    height:400,    //baseParams:{start:0,limit:5}    //可以选择行数    sm:new Ext.grid.RowSelectionModel({        //设置为单选           singleSelect:true    }    bbar:new Ext.PagingToolbar({              store:this.store,        //一页显示多少个        pageSize:5      }),    //绑定store中的数据到列中    columns:[{       header:"类型",       dataIndex:"type"    },{       header:"金额",       dataIndex:"money"        }]        });  /*       this.getStore().on("load",function(_store){    //_store.getTotalCount()中值的数量    alert(_store.getTotalCount());     });*/  this.getStore().load({params:{start:0,limit:5}});  }              });