Chapter 15: JavaServer Pages: Part I

Introduction

• Java based technology for creating dynamic web pages
• JSP scripts use XML, HTML and Java code
• JSP scripts are stored on web servers
• JSP scripts are suffixed with .jsp
• JSP pages are ultimately compiled into Java servlet classes

Apache Tomcat

• Web site
• I downloaded and installed the Tomcat 5.5.9 exe binary
• You will need to generate an admin password during the installation process.
• If you are successful, http://localhost:8080 will generate a Congratulations page
• By default, JSP pages that you create must appear in the following directory (or one of its subdirectories): C:\Program Files\Apache Software Foundation\Tomcat 5.5\webapps\ROOT
• Can be used as a stand-alone web server and as a JSP engine
• The Tomcat server detects newly created directories only when it starts

Simple JSP Example

• test.jsp
• include.html

JSP Element Groups

1. Directives: page, include, taglib
2. Scripting Elements: declarations, expressions, code fragments (scriptlets)
3. Comments
4. Actions

Directives

Page Directives

• Place at top of JSP file
• Syntax: <%@ page attribute1="value1" ... %>
• attribute: import="java.util.*"
• attribute: session="true" or session="false" (default is "true")
• attribute: buffer="10kb" or buffer="none" (not as important, default is server specific, but at least "8kb")
• attribute: isThreadSafe="true" (default is "true")

Include Directives

• Static Includes - done at page translation time. e.g. <%@ include file="whatever.html" %>
• Dyamic Includes - done at request time e.g. <jsp:include page="whatever.html" flush="true" />

Scripting Elements

JSP Declarations

• Have instance duration
• <%! private int count = 0; %>
• <%! public int incrementCount() { return count++; } %>

JSP Expressions

• <%= incrementCount() %>

JSP Scriptlets

• Declarations in scriptlets have local duration
• <% valid Java code %>

Comments

• <!-- content comment --> - returned by server
• <%-- code comment --%> - not returned by server
• <% /* code comment */ %> - not returned by server
• <% // single line code comment %> - not returned by server

Exercise

Install Apache Tomcat on your laptop. Create a "hi world" servlet. Demo the servlet to either Jack or John. 3 points.