44 lines
1.3 KiB
Java
44 lines
1.3 KiB
Java
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Handling invalid sessions
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package com.ack.web.servlet;
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import java.io.IOException;
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import java.io.PrintWriter;
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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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public class HandlingInvalidSessions extends HttpServlet {
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public void goGet( HttpServletRequest req, HttpServletResponse res )
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throws ServletException, IOException {
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res.setContentType( "text/html" );
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PrintWriter pw = res.getWriter();
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pw.println( "<HTML><BODY>" );
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HttpSession theSession = req.getSession();
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try {
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Object obj = theSession.getAttribute( "counter" );
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/**
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* the above call will throw an IllegalStateException
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* if theSession has been invalidated (e.g. by the
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* container or by another servlet)
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*
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* a defensive servlet programmer should wrap all accesses
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* to a servlet session (not just getAttribute()) in a
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* try/catch block so that they can take the appropriate
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* action to handle the case where a session is destroyed
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* at anytime
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*/
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}
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catch( IllegalStateException ise ) {
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// handle invalid session here
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}
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pw.println( "</BODY></HTML>" );
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}
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}
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