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40

Chapter 2 First Servlets

Listing 2.8 ShowMessage.java 

package coreservlets;

import java.io.*;

import javax.servlet.*;

import javax.servlet.http.*;

/** Example using servlet initialization. Here, the message

 *  to print and the number of times the message should be

 *  repeated is taken from the init parameters.

 */

public class ShowMessage extends HttpServlet {

  private String message;

  private String defaultMessage = "No message.";

  private int repeats = 1;

  public void init(ServletConfig config)

      throws ServletException {

    // Always call super.init

    super.init(config);

    message = config.getInitParameter("message");

    if (message == null) {

      message = defaultMessage;

    }

    try {

      String repeatString = config.getInitParameter("repeats");

      repeats = Integer.parseInt(repeatString);

    } catch(NumberFormatException nfe) {

      // NumberFormatException handles case where repeatString

      // is null *and* case where it is something in an

      // illegal format. Either way, do nothing in catch,

      // as the previous value (1) for the repeats field will

      // remain valid because the Integer.parseInt throws

      // the exception *before* the value gets assigned

      // to repeats.

    }

  }

    public void doGet(HttpServletRequest request,

                    HttpServletResponse response)

        throws ServletException, IOException {

      response.setContentType("text/html");

      PrintWriter out = response.getWriter();

      String title = "The ShowMessage Servlet";

      out.println(ServletUtilities.headWithTitle(title) +

                  "\n" +

                  "
" + title + "
");

Second edition of this book: www.coreservlets.com; Sequel: www.moreservlets.com.

Servlet and JSP training courses by book's author: courses.coreservlets.com.