网上搜索了一篇文章,代码和注释都还不错,虽然没具体使用,不过先copy下来,等着测试咯.
作者是园子里面的 jecray兄弟
拒绝session丢失 利用DIV层实现对模态窗口的模拟
使用window.showModalDialog进行信息的提示，相当方便，也容易控制外观和布局。但是存在一个严重的问题，就是Session丢失。当在A页面进行showModalDialog时，弹出的模态窗口open新页面或new dialog()时，会得不到A页面中的Session，这样就严重地限制了他的使用范围。
进一步的使用模式窗口可以发现session的丢失总是便随页面的刷新
1.在普通页面中弹出模式窗口且进行new dialog()操作时 会造成该进程中所有页面session的丢失
2.在模式窗口嵌套使用时 弹出的模式窗口并不会使父模式窗口的session丢失 但是会取不到父模式窗口的值
3.在弹出的模式窗口中使用js脚本需要验证表单时 如果出现return true or false之类的语句，会造成模态窗口session的丢失。
用showModalDialog经常出现这样那样奇怪的问题，因此最好少用showModalDialog。替代的方法就是用DIV来模拟实现模式窗口相同的功能。
html代码如下
<div id="id2"> <!--这个是弹出的层--> <table height="100" width="200"> <tr> <td> <div id="ShowMSG"></div> </td> </tr> <tr><td align="center"><input class="Button60" onclick="divhide()" type="button" value="关闭" name="btnDo">
</td>
</tr>
</table>
</div>
<div id="id1">这里是弹出层后的背景 可以不放内容</div>
</tr> </table></div><div id="id1">这里是弹出层后的背景 可以不放内容</div>在Css中设置弹出窗口的颜色背景透明度等
#id1{100%;height:100%;background-color:#000;position:absolute;top:0;left:0;z-index:49;display:none; filter:progid:DXImageTransform.Microsoft.Alpha(opacity=25);
}#id2{top:200px;position:absolute;z-index:50;display:none;border:3px solid #E5E5E5; left:100px;background-color:white;}js代码如下 可以对层进行拖拽 随意进行移动
function divshow(showmsg){ //弹出窗口
document.getElementById("id1").style.height=window.screen.height+"px";document.getElementById("id1").style.width=window.screen.width+"px";document.getElementById("id1").style.display='block';document.getElementById("id2").style.display='block';document.getElementById("ShowMSG").innerText = showmsg;}function divhide(){ //隐藏窗口 document.getElementById("id1").style.display='none'document.getElementById("id2").style.display='none'}self.onError=null; currentX = currentY = 0; whichIt = null; lastScrollX = 0; lastScrollY = 0; NS = (document.layers) ? 1 : 0; IE = (document.all) ? 1: 0; <!-- STALKER CODE --> function heartBeat() { 
if(IE) { diffY = document.body.scrollTop; diffX = document.body.scrollLeft; } 
if(NS) { diffY = self.pageYOffset; diffX = self.pageXOffset; } if(diffY != lastScrollY) { percent = .1 * (diffY - lastScrollY); if(percent > 0) percent = Math.ceil(percent); else percent = Math.floor(percent); if(IE) document.all.id2.style.pixelTop += percent; if(NS) document.id2.top += percent; lastScrollY = lastScrollY + percent; 
} if(diffX != lastScrollX) { percent = .1 * (diffX - lastScrollX); if(percent > 0) percent = Math.ceil(percent); else percent = Math.floor(percent); if(IE) document.all.id2.style.pixelLeft += percent; if(NS) document.id2.left += percent; lastScrollX = lastScrollX + percent; } } <!-- /STALKER CODE --> <!-- DRAG DROP CODE --> function checkFocus(x,y) { stalkerx = document.id2.pageX; stalkery = document.id2.pageY; stalkerwidth = document.id2.clip.width; stalkerheight = document.id2.clip.height; if( (x > stalkerx && x < (stalkerx+stalkerwidth)) && (y > stalkery && y < (stalkery+stalkerheight))) return true; else return false; } function grabIt(e) { if(IE) { whichIt = event.srcElement; while (whichIt.id.indexOf("id2") == -1) { whichIt = whichIt.parentElement; if (whichIt == null) { return true; } } whichIt.style.pixelLeft = whichIt.offsetLeft; whichIt.style.pixelTop = whichIt.offsetTop; currentX = (event.clientX + document.body.scrollLeft); currentY = (event.clientY + document.body.scrollTop); } else { window.captureEvents(Event.MOUSEMOVE); if(checkFocus (e.pageX,e.pageY)) { whichIt = document.id2; stalkerTouchedX = e.pageX-document.id2.pageX; StalkerTouchedY = e.pageY-document.id2.pageY; } } return true; } function moveIt(e) { if (whichIt == null) { return false; } if(IE) { newX = (event.clientX + document.body.scrollLeft); newY = (event.clientY + document.body.scrollTop); distanceX = (newX - currentX); distanceY = (newY - currentY); currentX = newX; currentY = newY; whichIt.style.pixelLeft += distanceX; whichIt.style.pixelTop += distanceY; if(whichIt.style.pixelTop < document.body.scrollTop) whichIt.style.pixelTop = document.body.scrollTop; if(whichIt.style.pixelLeft < document.body.scrollLeft) whichIt.style.pixelLeft = document.body.scrollLeft; if(whichIt.style.pixelLeft > document.body.offsetWidth - document.body.scrollLeft - whichIt.style.pixelWidth - 20) whichIt.style.pixelLeft = document.body.offsetWidth - whichIt.style.pixelWidth - 20;if(whichIt.style.pixelTop > document.body.offsetHeight + document.body.scrollTop - whichIt.style.pixelHeight - 5) whichIt.style.pixelTop = document.body.offsetHeight + document.body.scrollTop - whichIt.style.pixelHeight - 5; event.returnValue = false; } else { whichIt.moveTo(e.pageX-StalkerTouchedX,e.pageY-StalkerTouchedY); if(whichIt.left < 0+self.pageXOffset) whichIt.left = 0+self.pageXOffset; if(whichIt.top < 0+self.pageYOffset) whichIt.top = 0+self.pageYOffset; if( (whichIt.left + whichIt.clip.width) >= (window.innerWidth+self.pageXOffset-17)) whichIt.left = ((window.innerWidth+self.pageXOffset)-whichIt.clip.width)-17; if( (whichIt.top + whichIt.clip.height) >= (window.innerHeight+self.pageYOffset-17)) whichIt.top = ((window.innerHeight+self.pageYOffset)-whichIt.clip.height)-17; return false;} return false; } function dropIt() { whichIt = null; if(NS) window.releaseEvents (Event.MOUSEMOVE); return true; } <!-- DRAG DROP CODE --> if(NS) { window.captureEvents(Event.MOUSEUP|Event.MOUSEDOWN);window.onmousedown = grabIt;window.onmousemove = moveIt; window.onmouseup = dropIt; } if(IE) { document.onmousedown = grabIt; document.onmousemove = moveIt; document.onmouseup = dropIt; } if(NS || IE) action = window.setInterval("heartBeat()",1)在页面中调用divshow()就可以弹出仿照的模式窗口，这样就不会出现丢失session的问题，而且视觉效果很好。