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