59 lines
1.7 KiB
Java
59 lines
1.7 KiB
Java
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Session item notification
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package com.ack.web.servlet;
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import java.io.IOException;
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import java.io.Serializable;
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import javax.servlet.ServletException;
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import javax.servlet.http.HttpServlet;
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import javax.servlet.http.HttpServletRequest;
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import javax.servlet.http.HttpServletResponse;
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import javax.servlet.http.HttpSession;
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import javax.servlet.http.HttpSessionBindingEvent;
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import javax.servlet.http.HttpSessionBindingListener;
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public class SessionItemNotification extends HttpServlet {
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public void doGet( HttpServletRequest req, HttpServletResponse res )
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throws ServletException, IOException {
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HttpSession session = req.getSession();
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session.setAttribute( "cone", new KnowAllItem( "snake eyes" ) );
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session.removeAttribute( "cone" );
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res.getWriter().println( "check your console..." );
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}
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}
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/**
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* By implementing HttpSessionBindingListener, KnowAllItem objects get
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* informed when they are added and/or removed from a servlet session
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*
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* Also, remember to make you session items serializable
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*/
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class KnowAllItem implements HttpSessionBindingListener, Serializable {
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private String id;
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public KnowAllItem( String theId ) {
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id = theId;
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}
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public void valueBound( HttpSessionBindingEvent evt ) {
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System.out.println( "added KnowAllItem to session -> " + dump( evt ) );
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}
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public void valueUnbound( HttpSessionBindingEvent evt ) {
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System.out.println( "removed KnowAllItem from session -> " + dump( evt ) );
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}
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private String dump( HttpSessionBindingEvent evt ) {
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return "\n attribute name: " + evt.getName() + "\n session: " +
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evt.getSession() + "\n attribute value: " + evt.getValue();
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}
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public String toString() {
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return id;
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}
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}
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