Java中的枚举 http://blog.youkuaiyun.com/s_liang/article/details/5471633
java.util.Enumeration
Enumeration<E>
hasMoreElements();
nextElement();
eg: getAttributeNames()返回的是一个枚举类型
<%
for (Enumeration e = request.getAttributeNames(); e.hasMoreElements();)
{
Object o = e.nextElement();
out.println((String) o +
" :
"
+ request.getAttribute((String) o) +
"<br><hr>
");
}
%>