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The Java EE 6 Tutorial

Examining the hello2 Web Module

The hello2 application behaves almost identically to the hello1 application, but it is implemented using Java Servlet technology instead of JavaServer Faces technology. You can use a text editor to view the application files, or you can use NetBeans IDE.

ProcedureTo View the hello2 Web Module Using NetBeans IDE

  1. In NetBeans IDE, select File->Open Project.

  2. In the Open Project dialog, navigate to:


    tut-install/examples/web/

  3. Select the hello2 folder.

  4. Select the Open as Main Project check box.

  5. Expand the Source Packages node, then the servlets node.

  6. Double-click the GreetingServlet.java file to view it.

    This servlet overrides the doGet method, implementing the GET method of HTTP. The servlet displays a simple HTML greeting form whose Submit button, like that of hello1, specifies a response page for its action. The following excerpt begins with the @WebServlet annotation that specifies the URL pattern, relative to the context root:

    @WebServlet("/greeting")
public class GreetingServlet extends HttpServlet {

    @Override
    public void doGet(HttpServletRequest request,
            HttpServletResponse response)
            throws ServletException, IOException {

        response.setContentType("text/html");
        response.setBufferSize(8192);
        PrintWriter out = response.getWriter();

        // then write the data of the response
        out.println("<html>"
                + "<head><title>Servlet Hello</title></head>");

        // then write the data of the response
        out.println("<body  bgcolor=\"#ffffff\">"
                + "<img src=\"duke.waving.gif\" alt=\"Duke waving\">"
                + "<h2>Hello, my name is Duke. What's yours?</h2>"
                + "<form method=\"get\">"
                + "<input type=\"text\" name=\"username\" size=\"25\">"
                + "<p></p>"
                + "<input type=\"submit\" value=\"Submit\">"
                + "<input type=\"reset\" value=\"Reset\">"
                + "</form>");

        String username = request.getParameter("username");
        if (username != null && username.length() > 0) {
            RequestDispatcher dispatcher =
                    getServletContext().getRequestDispatcher("/response");

            if (dispatcher != null) {
                dispatcher.include(request, response);
            }
        }
        out.println("</body></html>");
        out.close();
    }
    ...

  7. Double-click the ResponseServlet.java file to view it.

    This servlet also overrides the doGet method, displaying only the response. The following excerpt begins with the @WebServlet annotation, which specifies the URL pattern, relative to the context root:

    @WebServlet("/response")
public class ResponseServlet extends HttpServlet {

    @Override
    public void doGet(HttpServletRequest request,
            HttpServletResponse response)
            throws ServletException, IOException {
        PrintWriter out = response.getWriter();

        // then write the data of the response
        String username = request.getParameter("username");
        if (username != null && username.length() > 0) {
            out.println("<h2>Hello, " + username + "!</h2>");
        }
    }
    ...

  8. Under the Web Pages node, expand the WEB-INF node and double-click the sun-web.xml file to view it.

    In the General tab, observe that the Context Root field is set to /hello2.

    For this simple servlet application, a web.xml file is not required.