SimplerHelloWWW.java Servlet that uses ServletUtilities to simplify the generation of the DOCTYPE and HEAD part of the servlet.

SimplerHelloWWW.java  Servlet that uses ServletUtilities  to simplify the generation of the DOCTYPE and HEAD part of the servlet.

package cwp;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

/** Simple servlet that generates HTML. This variation of
 *  HelloWWW uses the ServletUtilities utility class
 *  to generate the DOCTYPE, HEAD, and TITLE.
 *  


 *  Taken from Core Web Programming Java 2 Edition
 *  from Prentice Hall and Sun Microsystems Press,
 *  .
 *  May be freely used or adapted.
 */

public class SimplerHelloWWW extends HttpServlet {
  public void doGet(HttpServletRequest request,
                    HttpServletResponse response)
      throws ServletException, IOException {
    response.setContentType("text/html");
    PrintWriter out = response.getWriter();
    out.println(ServletUtilities.headWithTitle("Hello WWW") +
                "\n" +
                "
Hello WWW
\n" +
                "");
  }
}


Servlet Utilities

package cwp;

import javax.servlet.*;
import javax.servlet.http.*;

/** Some simple time savers. Note that most are static methods.
 *  


 *  Taken from Core Web Programming Java 2 Edition
 *  from Prentice Hall and Sun Microsystems Press,
 *  May be freely used or adapted.
 */

public class ServletUtilities {
  public static final String DOCTYPE =
    "";

  public static String headWithTitle(String title) {
    return(DOCTYPE + "\n" +
           "\n" +
           "\n");
  }

  /** Read a parameter with the specified name, convert it
   *  to an int, and return it. Return the designated default
   *  value if the parameter doesn't exist or if it is an
   *  illegal integer format.
  */
  
  public static int getIntParameter(HttpServletRequest request,
                                    String paramName,
                                    int defaultValue) {
    String paramString = request.getParameter(paramName);
    int paramValue;
    try {
      paramValue = Integer.parseInt(paramString);
    } catch(NumberFormatException nfe) { // null or bad format
      paramValue = defaultValue;
    }
    return(paramValue);
  }

  /** Given an array of Cookies, a name, and a default value,
   *  this method tries to find the value of the cookie with
   *  the given name. If there is no cookie matching the name
   *  in the array, then the default value is returned instead.
   */
  
  public static String getCookieValue(Cookie[] cookies,
                                      String cookieName,
                                      String defaultValue) {
    if (cookies != null) {
      for(int i=0; i' with
   *  '>', and (to handle cases that occur inside attribute
   *  values), all occurrences of double quotes with
   *  '"' and all occurrences of '&' with '&'.
   *  Without such filtering, an arbitrary string
   *  could not safely be inserted in a Web page.
   */

  public static String filter(String input) {
    StringBuffer filtered = new StringBuffer(input.length());
    char c;
    for(int i=0; i') {
        filtered.append(">");
      } else if (c == '"') {
        filtered.append(""");
      } else if (c == '&') {
        filtered.append("&");
      } else {
        filtered.append(c);
      }
    }
    return(filtered.toString());
  }
}