📄 guestbook_bean.jsp
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<%@ page language=java import='jsp.*'%><%!//// Rewriting the guestbook using beans and a cached included page to// display the contents.//// This architecture is suitable for most display pages. When the// calculations and state machines become more complicated, the// full-blown template architecture will be more appropriate.//// The cached included page architecture is appropriate when the top page// is user specific but a subpage is the same for all users and is slow// dynamic page like a database query.//// For this example, creating a separate bean to handle the guestbook// is overkill, but illustrates how a more complicated application would// start encapsulating its data.//%><head><title>JSP Guest Book</title></head><body bgcolor='white'><h1>JSP Guest Book</h1><!-- - Retrieve the guestbook from the application, creating if necessary - GuestBook is a custom bean, living in templates/WEB-INF/classes. --><jsp:useBean id='guest_book' class='jsp.GuestBook' scope=application/><!-- - "controller" code, handling state changes and user input --><%// If already logged in, grab the user name.String name = (String) session.getAttribute("name");// Try to log the user inString user = request.getParameter("Name");String passwd = request.getParameter("Password");if (user == null) user = "";else if ("quidditch".equals(passwd)) { name = user; session.setAttribute("name", name);}// Update the guestbook if the user has a new comment.String comment = request.getParameter("Comment");if (comment != null && name != null) guest_book.addGuest(name, comment);// Try to get the old commentif (comment == null && name != null) { Guest guest = (Guest) guest_book.getGuest(name); if (guest != null) comment = guest.getComment();}if (comment == null) comment = "";%><!-- - Display the guestbook. Because guestbook_inc is cached, it will only - be updated every 15 seconds, but the outer page is updated immediately. --><jsp:include page='guestbook_inc.jsp'/><hr><!-- - If the user is not logged in, show him a login form. - The action is encoded to allow URL-based sessions. --><% if (name != null) { %><form action='<%= response.encodeURL("guestbook_bean.jsp") %>' method='POST'><table><tr><td>Name:<td><%= name %><tr><td>Comment:<td><input size="40" name="Comment" value="<%= comment %>"></table></form><!- - Otherwise, if the user is logged in, let him change the comment. --><% } else { %><form action="<%= response.encodeURL("guestbook_bean.jsp") %>" method="POST"><table><tr><td>Name:<td><input name='Name' value='<%= user %>'><tr><td>Password:<td><input name='Password' type='password'><tr><td>Hint:<td>The password is 'quidditch'<tr><td><input type=submit value='Login'></table></form><% } %></body>⌨️ 快捷键说明
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