Ext.grid.DynamicGrid = Ext.extend(Ext.grid.GridPanel, {
initComponent: function() {
//创建store
var ds = new Ext.data.Store({
url: this.storeUrl,
reader: new Ext.data.JsonReader()
});

//设置默认配置
var config = {
viewConfig: {
forceFit: true
},
enableColLock: false,
loadMask: true,
border: true,
stripeRows: true,
ds: ds,
columns: []
};

//给分页PagingToolbar绑定store
this.bbar.bindStore(ds, true);

Ext.apply(this, config);
Ext.apply(this.initialConfig, config);
Ext.grid.DynamicGrid.superclass.initComponent.apply(this, arguments);
},

onRender: function(ct, position) {
this.colModel.defaultSortable = true;
Ext.grid.DynamicGrid.superclass.onRender.call(this, ct, position);

this.el.mask('Loading...');
this.store.on('load', function() {
if (typeof(this.store.reader.jsonData.columns) === 'object') {
var columns = [];

if (this.rowNumberer) {
columns.push(new Ext.grid.RowNumberer());
}

if (this.checkboxSelModel) {
columns.push(new Ext.grid.CheckboxSelectionModel());
}

Ext.each(this.store.reader.jsonData.columns,
function(column) {
columns.push(column);
}
);

this.getColumnModel().setConfig(columns);
}

this.el.unmask();
}, this);

this.store.load();
}
});

?

var dynamicGrid = new Ext.grid.DynamicGrid({
title: '测试动态列',
renderTo: 'dynamic-grid',
storeUrl: 'goods/dynamicGrid.do',
width : 600,
height: 200,
rowNumberer: true,
checkboxSelModel: true,
sm: new Ext.grid.CheckboxSelectionModel(),
bbar : new Ext.PagingToolbar({
pageSize : 5,
displayInfo : true,
displayMsg : '显示第{0}到{1}条数据,共{2}条',
emptyMsg : "没有数据",
beforePageText : "第",
afterPageText : '页 共{0}页'
})
});

?

?

{
'metaData': {
'totalProperty': 'total',
'root': 'records',
'id': 'id',
'fields': [
{'name': 'id', 'type': 'int'},
{'name': 'name', 'type': 'string'}
]
},
'success': true,
'total': 50,
'records': [
{'id': '1', 'name': 'AAA'},
{'id': '2', 'name': 'BBB'}
],
'columns': [
{'header': '#', 'dataIndex': 'id'},
{'header': 'User', 'dataIndex': 'name'}
]
}

?

http://erhanabay.com/2009/01/29/dynamic-grid-panel-for-ext-js/