Editing Jakarta Servlet (section)

== Example ==
The following example servlet prints how many times its <code>service()</code> method was called.

Note that <code>HttpServlet</code> is a subclass of <code>GenericServlet</code>, an implementation of the <code>Servlet</code> interface.

The <code>service()</code> method of <code>HttpServlet</code> class dispatches requests to the methods <code>doGet()</code>, <code>doPost()</code>, <code>doPut()</code>, <code>doDelete()</code>, and so on; according to the HTTP request. In the example below <code>service()</code> is overridden and does not distinguish which HTTP request method it serves.
<syntaxhighlight lang="java">
import java.io.IOException;

import jakarta.servlet.ServletConfig;
import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

public class ServletLifeCycleExample extends HttpServlet {
    private Integer sharedCounter;

    @Override
    public void init(final ServletConfig config) throws ServletException {
        super.init(config);
        getServletContext().log("init() called");
        sharedCounter = 0;
    }

    @Override
    protected void service(final HttpServletRequest request, final HttpServletResponse response) throws ServletException, IOException {
        getServletContext().log("service() called");
        int localCounter;
        synchronized (sharedCounter) {
            sharedCounter++;
            localCounter = sharedCounter;
        }
        response.getWriter().write("Incrementing the count to " + localCounter);  // accessing a local variable
        response.getWriter().flush();   // flush response
    }

    @Override
    public void destroy() {
        getServletContext().log("destroy() called");
    }
}
</syntaxhighlight>