弹出DIV

css：
#uploadBackground {

filter:alpha(opacity=50);
-moz-opacity:0.5;
opacity:0.5;
background-color:white;
width:100%;
height:100%;
z-index:1000;
position: absolute;
left:0;
top:0;
overflow: hidden;
display:none;
}

#uploadDiv {
filter:alpha(opacity=50);
border:solid 4px #66b3ff;
background:white;
width:240px;
height:100px;
z-index:1001;
position: absolute;
top:50%;
left:50%;
margin:-100px 0 0 -100px;
display:none;
border-radius: 5px;
}
jsp：
<div id="uploadBackground">
    </div>   
    <div id="uploadDiv">
                  <div class="uploadTitle" style="font-size:14px;text-align: center; margin: 20px 20px 10px 20px;">
                  上传文件
                  </div>
                  <div id="div_uploadImg" class="div_uploadImg" style="text-align: center;">
                     <img src="../../img/loading.gif"/>
                  </div>
    </div>
js：

function showfloatall(num)//这个是显示要弹出的层
    {
      var range = getRange();
          var divvv1="uploadBackground";
           var divvv2="uploadDiv";
            document.getElementById(divvv1).style.width = range.width + "px";
           document.getElementById(divvv1).style.height = range.height + "px";
           jQuery("#uploadBackground").show();
           jQuery("#uploadDiv").show("slow");
    }

        function getRange()                      //得到屏幕的大小
        {
              var top     = document.body.scrollTop;
              var left    = document.body.scrollLeft;
              var height  = document.body.clientHeight;
              var width   = document.body.clientWidth;

              if (top==0 && left==0 && height==0 && width==0)
              {
                top     = document.documentElement.scrollTop;
                left    = document.documentElement.scrollLeft;
                height  = document.documentElement.clientHeight;
                width   = document.documentElement.clientWidth;
              }
              return  {top:top  ,left:left ,height:height ,width:width } ;
        }