获取单选按钮组的选中值

var radioGroup = new Ext.form.RadioGroup({
        width: 130,
        id: 'selected',
        layout: 'form',
        items: [{
            name: 'orders',
            inputValue: '0',
            boxLabel: '订单统计',
            checked: true
        }, {
            name: 'orders',
            inputValue: '1',
            boxLabel: '公司统计'
        }, {
            name: 'orders',
            inputValue: '2',
            boxLabel: '员工统计'
        }],
        listeners : {
            'change': function() {
                //这里可以显示单选按钮的选中值
                console.dir(Ext.getCmp('selected').lastValue.orders);
            }
        }
    });