修改Extjs Grid和PagingBar的Store

 Ext.getCmp("_Grid").reconfigure(window.store, gcm);//重新绑定Grid
 Ext.getCmp("_PagingToolbar").bindStore(window.store, false);//重新设置分页条
 window.store.load({
                 params: {
                 start: 0,
                 limit: pageSize,
                  foo: 'bar'
                  },
                  callback: function (r, options, success) {
                  }
});