datagrid分页转换设置

function requisitions_accept_search_pagechange(gridId,formId){
var gridObj = $("#"+gridId);
var formObj = $("#"+formId);
var t=gridObj.datagrid('options').pageSize;
if(t==20){
gridObj.datagrid({
pageSize : 100,
       pageList: [100, 200, 300, 500]});
}else{
gridObj.datagrid({
   pageSize : 20,
   pageList: [10, 20, 30, 40, 50]});
}
gridObj.datagrid("load",sys.serializeJson(formObj));

}