鼠标事件 更换背景色或背景图片
//当鼠标移至上面时更换背景图片
onmouseover="this.style.backgroundImage='url(${pageContext.request.contextPath}/images/menuMouseOver.gif)'"
//当鼠标移开时更换背景图片
onmouseout="this.style.backgroundImage='url(${pageContext.request.contextPath}/images/menu_bg.png)'"

//当鼠标移至上面时更换背景色
onmouseover="this.style.backgroundColor='#00000'"
//当鼠标移开时更换背景色
onmouseout="this.style.backgroundColor='#FFFFFF