window.showModalDialog两次加载问题清除缓存方法

var frmHeight = 352;
var frmWidth = 508;
var frmTop = (window.screen.height - frmHeight) / 2;
var frmLeft = (window.screen.width - frmWidth / 2);
var url = "ChosePerson.aspx";
var parameter = "dialogHeight:" + frmHeight + "px;dialogWidth:" + frmWidth + "px;dialogTop" + frmTop + "px;dialogLeft" + frmLeft + "px;scroll:0;status:0;reziable:1;";
var rval = window.showModalDialog(url, "", parameter);
window.showModalDialog()//第一次加载是走page_load()方法的，第二次加载时就不走page_load();