// Fig. 19.13: SessionExample.java
// Using sessions.
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
public class SessionExample extends HttpServlet {
private final static String names[] =
{ "C", "C++", "Java", "Visual Basic 6" };
private final static String isbn[] = {
"0-13-226119-7", "0-13-528910-6",
"0-13-012507-5", "0-13-528910-6" };
public void doPost( HttpServletRequest request,
HttpServletResponse response )
throws ServletException, IOException
{
PrintWriter output;
String language = request.getParameter( "lang" );
// Get the user's session object.
// Create a session (true) if one does not exist.
HttpSession session = request.getSession( true );
// add a value for user's choice to session
session.putValue( language, getISBN( language ) );
response.setContentType( "text/html" );
output = response.getWriter();
// send HTML page to client
output.println( "" );
output.println( "Sessions" );
output.println( "" );
output.println( "Welcome to Sessions!
" );
output.println( "
" );
output.println( language );
output.println( " is a great language." );
output.println( "" );
output.close(); // close stream
}
public void doGet( HttpServletRequest request,
HttpServletResponse response )
throws ServletException, IOException
{
PrintWriter output;
// Get the user's session object.
// Don't create a session (false) if one does not exist.
HttpSession session = request.getSession( false );
// get names of session object's values
String valueNames[];
if ( session != null )
valueNames = session.getValueNames();
else
valueNames = null;
response.setContentType( "text/html" );
output = response.getWriter();
output.println( "
" );
output.println( "Sessions II" );
output.println( "" );
if ( valueNames != null && valueNames.length != 0 ) {
output.println( "Recommendations
" );
// get value for each name in valueNames
for ( int i = 0; i < valueNames.length; i++ ) {
String value =
(String) session.getValue( valueNames[ i ] );
output.println(
valueNames[ i ] + " How to Program. " +
"ISBN#: " + value + "
" );
}
}
else {
output.println( "No Recommendations
" );
output.println( "You did not select a language or" );
output.println( "the session has expired." );
}
output.println( "" );
output.close(); // close stream
}
private String getISBN( String lang )
{
for ( int i = 0; i < names.length; ++i )
if ( lang.equals( names[ i ] ) )
return isbn[ i ];
return ""; // no matching string found
}
}
/**************************************************************************
* (C) Copyright 1999 by Deitel & Associates, Inc. and Prentice Hall. *
* All Rights Reserved. *
* *
* DISCLAIMER: The authors and publisher of this book have used their *
* best efforts in preparing the book. These efforts include the *
* development, research, and testing of the theories and programs *
* to determine their effectiveness. The authors and publisher make *
* no warranty of any kind, expressed or implied, with regard to these *
* programs or to the documentation contained in these books. The authors *
* and publisher shall not be liable in any event for incidental or *
* consequential damages in connection with, or arising out of, the *
* furnishing, performance, or use of these programs. *
*************************************************************************/