package coreservlets;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
/** Illustrates the value of persistent HTTP connections for
* pages that includes many images, applet classes, or
* other auxiliary content that would otherwise require
* a separate connection to retrieve.
*
* Taken from Core Servlets and JavaServer Pages
* from Prentice Hall and Sun Microsystems Press,
* http://www.coreservlets.com/.
* © 2000 Marty Hall; may be freely used or adapted.
*/
public class PersistentConnection extends HttpServlet {
public void doGet(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
ByteArrayOutputStream byteStream =
new ByteArrayOutputStream(7000);
PrintWriter out = new PrintWriter(byteStream, true);
String persistenceFlag =
request.getParameter("usePersistence");
boolean usePersistence =
((persistenceFlag == null) ||
(!persistenceFlag.equals("no")));
String title;
if (usePersistence) {
title = "Using Persistent Connection";
} else {
title = "Not Using Persistent Connection";
}
out.println(ServletUtilities.headWithTitle(title) +
"
\n" +
"" + title + "
");
int numImages = 100;
for(int i=0; i");
if (usePersistence) {
response.setContentLength(byteStream.size());
}
byteStream.writeTo(response.getOutputStream());
}
private String makeImage(int n, boolean usePersistence) {
String file =
"/servlet/coreservlets.ImageRetriever?gifLocation=" +
"/bullets/bullet" + n + ".gif";
if (!usePersistence)
file = file + "&usePersistence=no";
return("![\"\"](\"")
");
}
public void doPost(HttpServletRequest request,
HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}