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54 lines
1.8 KiB
Java
54 lines
1.8 KiB
Java
Servlet counter
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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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public class ServletCounter extends HttpServlet {
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private int instanceCount;
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private static int classCount;
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// process the HTTP get request
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public void doGet( HttpServletRequest request, HttpServletResponse response )
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throws ServletException, IOException {
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response.setContentType( "text/html" );
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PrintWriter out = new PrintWriter( response.getOutputStream() );
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out.println( "<html>" );
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out.println( "<head><title>ServletCounter</title></head>" );
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out.println( "<body>" );
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out.println( "<h3>Hit the browser refresh button!<br>" );
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out.println( "On 10, you'll get an exception, hit refresh again</h3>" );
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out.println( "<p><hr noshade><p>" );
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// when you get to 10, throw exception to cause the
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// this servlet instance to be destroyed and reloaded
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if( instanceCount > 0 && ( instanceCount / 10 ) > 0 ) {
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instanceCount = 0;
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throw new ServletException( "Hit Refresh Again" );
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}
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// synchronize on the servlet instance before updating the counter
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synchronized( this ) {
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// number of times this servlet instance has been accessed
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out.println( "<br>Servlet Instance Count -> " + instanceCount++ );
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}
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// sychronize on the servlet class before updating the class-based counter
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synchronized( ServletCounter.class ) {
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// collective total of all accesses to all servlet instances created
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// by this class
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out.println( "<br>Servlet Total Request Count -> " + classCount++ );
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}
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out.println( "</body></html>" );
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out.close();
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}
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}
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