public class SingleThreadConnection extends HttpServletimplements SingleThreadModel { Connection
public class SingleThreadConnection extends HttpServletimplements SingleThreadModel { Connection con = null; // database connection, one per pooled servlet instance public void init(ServletConfig config) throws ServletException { super.init(config); // Establish the connection for this instance con = establishConnection(); con.setAutoCommit(false); } public void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException { res.setContentType( text/plain ); PrintWriter out = res.getWriter(); // Use the connection uniquely assigned to this instance Statement stmt = con.createStatement(); // Update the database any number of ways // Commit the transaction con.commit(); } public void destroy() { if (con !=null) con.close(); } private Connection establishConnection() { // Not implemented. See Chapter 9. } } Background Processing Servlets can do more than simply persist between accesses. They can also execute between accesses. Any thread started by a servlet can continue executing even after the response has been sent. This ability proves most useful for long-running tasks whose incremental results should be made available to multiple clients. A background thread started in init()performs continuous work while requesthandling threads display the current status with doGet(). It’s a similar technique to that used in animation applets, where one thread changes the picture and another paints the display. Example 3-6 shows a servlet that searches for prime numbers above one quadrillion. It starts with such a large number to make the calculation slow enough to adequately demonstrate caching effects something we need for the next section. The algorithm it uses couldn’t be simpler: it selects odd-numbered candidates and attempts to divide them by every odd integer between 3 and their square root. If none of the integers evenly divides the candidate, it is declared prime. Example 3-6. On the hunt for primes
Quick Hint: If you are looking for best quality webspace to host and run your tomcat application check Vision tomcat hosting services