<h2>start -- ${start}</h2>
<h2>end -- ${end}</h2>
<fmt:formatDate  var="endDay"  type="date"  value="${start}" />
<fmt:formatDate  var="startDay" type="date"  value="${end}"  />
<fmt:parseDate var="e" value="${endDay}" pattern="yyyy-MM-dd"></fmt:parseDate>
<fmt:parseDate var="s" value="${startDay}" pattern="yyyy-MM-dd"></fmt:parseDate>
<fmt:formatNumber value="${(e.getTime()-s.getTime())/1000/60/60/24}" pattern="#0" var="num"/>
<h2>时间差：${num}</h2>