function document.oncontextmenu()//屏蔽鼠标右键
{
   return false;
}

function document.onkeydown()//屏蔽键盘F5
{
   if(window.event.keyCode == 116)
   {
     window.event.keyCode=0;
     event.cancelBubble=true;
     return false;
   }
}