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7.4 Using Persistent HTTP Connections

163

Listing 7.5  ServletUtilities.java 

package coreservlets;

import javax.servlet.*;

import javax.servlet.http.*;

public class ServletUtilities {

  // ... Other utilities shown earlier

  /** 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);

  }

  // ...

}

7.4 Using Persistent HTTP 

Connections

One of the problems with HTTP 1.0 was that it required a separate socket

connection for each request. When a Web page that includes lots of small

images or many applet classes is retrieved, the overhead of establishing all the

connections could be significant compared to the actual download time of the

documents. Many browsers and servers supported the  keep alive  extension

to address this problem. With this extension, the server tells the browser how

many bytes are contained in the response, then leaves the connection open

for a certain period of time after returning the document. The client detects

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

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