JSP文件本身是简单的。它从application获取留言本并在表中显示内容。通常，
application对象需要同步，因为一些客户端可能同时浏同一页面。
GuestJsp在jsp文件被调用之前小心处理了同步情况。
login.jsp: Display Guest Book <%@ page language=
javascript %>
<head>
<title>Hogwarts Guest Book</title>
</head>
<body bgcolor='white'>
<h1>Hogwarts Guest Book</h1>
<table>
<tr><td width='25%'><em>Name</em><td><em>Comment</em>
<%
var guestBook = application.attribute.guest_book
for (var guest in guestBook) {
out.writeln("<tr><td>" + guest.name + "<td>" + guest.comment);
}
%>
</table>
</body>
Hogwarts Guest Book
Name Comment
Harry Potter Griffindor Rules
Draco Malfoy Slytherin Rules
