关于EXT中PagingMemoryProxy

关于EXT中PagingMemoryProxy求助
首先贴个源代码：
     var columns = [
        { header: "学科类别", dataIndex: "lb", sortable: true },
            { header: "课程编号", dataIndex: "kcbh", sortable: true },
            { header: "课程名称", dataIndex: "kcmc", sortable: true },
            { header: "学时", dataIndex: "xs", sortable: true },
            { header: "学分", dataIndex: "xf", sortable: true },
            { header: "开课学期", dataIndex: "kkxq", sortable: true,renderer:function(v){return "<font color='red'>"+v+"</font>"} }
    ];
            var reader = new Ext.data.JsonReader({}, [
        { name: 'lb' },
        { name: 'kcbh' },
        { name: 'kcmc' },
        { name: 'xs' },
        { name: 'xf' },
        { name: 'kkxq' },
        { name: 'kkxy' },
        { name: 'khfs' },
        { name: 'bz' }
    ]);
           var vstore=new Ext.data.JsonStore({
            data:data1 ,
            fields: ["zydm", "zymc", "kclb", "xkzdfs"]
        });

            var store = new Ext.data.GroupingStore({
                reader: reader,
                proxy: new Ext.data.PagingMemoryProxy(data),
                groupField: 'lb',
                sortInfo: { field: 'kcbh', direction: "ASC" }
            });
            var grid1=new Ext.grid.GridPanel({
            title:"研究生专业培养方案 ",
            store: vstore,
            loadmask:true,
            clicksToEdit: 1,
            width: 600,
            renderTo: document.body,
             columns: [

{header: "专业代码", dataIndex: "zydm", sortable: true,width:150 },
            { header: "专业名称", dataIndex: "zymc", sortable: true, width:150},
            { header: "课程类别", dataIndex: "kclb", sortable: true, width:150},
            { header: "选课最低分数", dataIndex: "xkzdfs",
             sortable: true,
             renderer: function (v) { return "<font color='red'>" + v + "</font>" },width:145
             }
            ]});
     
            var grid = new Ext.grid.GridPanel({
                autoHeight: true,
                store: store,
                layout: 'fit',
                autoHeight: true,
                loadmask: true,
                bbar:new Ext.PagingToolbar({
                pagesize:5,
                store:store,
                displayInfo:true,
                displayMsg:'显示第{0}条到{1}条记录,一共{2}条',
                empty:"没有记录"
                }),
                columns: columns,
                view: new Ext.grid.GroupingView(),
                renderTo: document.body
            });
            store.load({ params: { start: 0, limit: 5} });
        });

在store中使用了PagingMemoryProxy进行静态分页，但是页面表格的显示没有进行分页，但是只显示了我所设定的PAGESIZE:5页的数据，是不是PagingMemoryProxy不支持JSON的数据分页，去解决
[解决办法]
可以支持，我就是在用PagingMemoryProxy　　你Ext.data.JsonStore要改成ArrayReader，可先在前台页面做测试，测好代码再跟后台java交互。