java code for Servlet Session Example

/*
* Copyright 2004 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* $Id: SessionExample.java,v 1.4 2004/03/18 16:40:33 jfarcand Exp $
*
*/

import java.io.*;
import java.text.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;

/**
* Example servlet showing request headers
*
* @author James Duncan Davidson
*/

public class SessionExample extends HttpServlet {

ResourceBundle rb = ResourceBundle.getBundle("LocalStrings");

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException {
response.setContentType("text/html");

PrintWriter out = response.getWriter();
out.println("");
out.println("");
out.println("");

String title = rb.getString("sessions.title");
out.println("");
out.println("");
out.println("");

// img stuff not req'd for source code html showing
// relative links everywhere!

// XXX
// making these absolute till we work out the
// addition of a PathInfo issue

out.println("");
out.println(" + "width=24 align=right border=0 alt=\"view code\">");
out.println("");
out.println(" + "width=24 align=right border=0 alt=\"return\">");

out.println("

" + title + "

");

HttpSession session = request.getSession(true);
out.println(rb.getString("sessions.id") + " " + session.getId());
out.println("
");
out.println(rb.getString("sessions.created") + " ");
out.println(new Date(session.getCreationTime()) + "
");
out.println(rb.getString("sessions.lastaccessed") + " ");
out.println(new Date(session.getLastAccessedTime()));

String dataName = request.getParameter("dataname");
String dataValue = request.getParameter("datavalue");
if (dataName != null && dataValue != null) {
session.setAttribute(dataName, dataValue);
}

out.println("

");
out.println(rb.getString("sessions.data") + "
");
Enumeration names = session.getAttributeNames();
while (names.hasMoreElements()) {
String name = (String) names.nextElement();
String value = session.getAttribute(name).toString();
out.println(HTMLFilter.filter(name) + " = "
+ HTMLFilter.filter(value) + "
");
}

out.println("

");
out.print("

out.print(response.encodeURL("SessionExample"));
out.print("\" ");
out.println("method=POST>");
out.println(rb.getString("sessions.dataname"));
out.println("");
out.println("
");
out.println(rb.getString("sessions.datavalue"));
out.println("");
out.println("
");
out.println("");
out.println("

");

out.println("

GET based form:
");
out.print("

out.print(response.encodeURL("SessionExample"));
out.print("\" ");
out.println("method=GET>");
out.println(rb.getString("sessions.dataname"));
out.println("");
out.println("
");
out.println(rb.getString("sessions.datavalue"));
out.println("");
out.println("
");
out.println("");
out.println("

");

out.print("

out.print(response
.encodeURL("SessionExample?dataname=foo&datavalue=bar"));
out.println("\" >URL encoded ");

out.println("");
out.println("");

out.println("");
out.println("");
}

public void doPost(HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException {
doGet(request, response);
}

}

/*
* Copyright 2004 The Apache Software Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/

/**
* HTML filter utility.
*
* @author Craig R. McClanahan
* @author Tim Tye
* @version $Revision: 1.2 $ $Date: 2004/03/18 16:40:34 $
*/

final class HTMLFilter {

/**
* Filter the specified message string for characters that are sensitive in
* HTML. This avoids potential attacks caused by including JavaScript codes
* in the request URL that is often reported in error messages.
*
* @param message
* The message string to be filtered
*/
public static String filter(String message) {

if (message == null)
return (null);

char content[] = new char[message.length()];
message.getChars(0, message.length(), content, 0);
StringBuffer result = new StringBuffer(content.length + 50);
for (int i = 0; i < content.length; i++) {
switch (content[i]) {
case '<':
result.append("<");
break;
case '>':
result.append(">");
break;
case '&':
result.append("&");
break;
case '"':
result.append(""");
break;
default:
result.append(content[i]);
}
}
return (result.toString());

}

}