var javawsInstalled = 0; 
var javaws142Installed=0; 
var javaws150Installed=0; 
isIE = "false";

if (navigator.mimeTypes && navigator.mimeTypes.length) 
{ 
x = navigator.mimeTypes['application/x-java-jnlp-file']; 
if (x) 
{ 
   javawsInstalled = 1; 
   javaws142Installed=1; 
   javaws150Installed=1; 
}

} else 
{ 
isIE = "true"; 
try { 
   var java = new ActiveXObject("JavaWebStart.isInstalled"); 
   // var java15 = new ActiveXObject("JavaWebStart.isInstalled.1.5.0.0");//1.5版本

   if(!java)
   {
    alert('你未安装Java虚拟机下载链接在网站底部JAva图标'); 
   }
   else
   {
    
   }
} catch(ex) { 
   alert('请安装Java虚拟机下载链接在网站底部JAva图标'); 
} 
}