Transcript An Introduction to JavaServer™ Pages

An Introduction to JavaServer™
Pages
Prepared by Nicole Swan
General JSP Information
 Most Common JSP Components
– Static HTML/XML components
– Special JSP tags
– Optionally, snippets of code written in Java called
“scriptlets”
 JSPs are parsed on the server side
– Translation phase occurs only once unless JSP is
updated
– Compiled class is then served to each client upon
request
Advantages of JSP
 Separation of static from dynamic content
 Write once run anywhere
 Dynamic content can be served in a variety of
formats
 Recommended web access layer for n-tier
architecture
 Completely leverages the Servlet API
(Source: http://developer.java.sun.com/developer/onlineTraining/JSPIntro/contents.html )
JSP vs. ASP
JSP
ASP
Native support only within
Web Server Support
Most popular web servers including Microsoft IIS or Personal
Apache, Netscape, Microsoft IIS.
Web Server.
Platform Support
Platform independent. Runs on all
Java-enabled platforms.
Is fully supported under
Windows.
Component Model
Reusable, cross-platform
components like JavaBeans, EJB,
and custom tag libraries.
Uses the Win32-based
COM component model.
Scripting
Java or JavaScript.
Supports VBScript and
JScript for scripting.
Security
Java security model.
Windows NT security
architecture.
Database Access
JDBC
Active Data Objects
Customizable Tags
Extensible with custom tag
libraries.
Not extensible and
cannot use custom tag
libraries.
(Source: http://developer.java.sun.com/developer/onlineTraining/JSPIntro/contents.html )
Basic JSP Syntax
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Directives
Declarations
Expressions
Comments
Scriptlets
Directives
 page directives are found at the top of most
JSP pages.
 Specify java packages to include, the page
language type, or the content type.
 Examples
<%@ page import=”java.util.*, com.foo.*”%>
<%@ page language=”java” %>
<%@ page contentType=“text/html” %>
Directives
 include directives are used to include static
html content or other JSP content.
 Example
<%@ include file=”menu.html” %>
<%@ include file=“menu.jsp”%>
Declarations
 Declarations are found within the <%! …
tag.
 Anything within this tag must be valid Java
code including all appropriate syntax.
 Example
<%! int i = 0; %>
<%! public void foo(){
out.println( i );
}
%>
%>
Expressions
 With expressions, the result of evaluating the
expression is directly included in the output of
the JSP page.
 Examples
<%= i %>
<%= fooBean.getName() %>
Comments
 JSP comments are enclosed in the
<%-- … --%> tag.
 Any comments in this format are not viewable
when viewing the page’s source in a browser.
 Example
<%-- This is a comment --%>
Note: Can still use HTML comments though they are viewable to
client
Scriptlets
 Scriptlets are used to embed code fragments
within a JSP page.
 The <% … %> tag is used.
 Example
<% for ( int i = 0; i < a.length; i++ ) { %>
<option value=”<%=a[i]%>”><%=a[i]%></option>
<% } %>
JSP Tag Libraries
 Allow Java developers to decouple static
HTML and complex server-side behaviors
 In a sense, are a replacement for scriptlets
 Required use by many companies in JSP
development
 Example
<%@ taglib uri=“mytags-taglib.tld” prefix=“mytag” %>
<mytag:if>
<mytag:condition>true</mytag:condition>
<mytag:then>Condition was true</mytag:then>
<mytag:else>Condition was false</mytag:then>
</mytag:if>
JavaBeans
 JavaBeans topic is broad and complex
 For our purposes, allow JSP developers to
decouple static HTML and complex serverside behaviors through the use of classes
JSP Development Environments
 Forte for Java (Community or Enterprise
edition)
– Provides syntax coloring which is nice
 Notepad
– Simple and readily available
 WYSIWYG environments
– Macromedia DreamWeaver
– Adobe GoLive
 Macromedia ColdFusion Studio
Web Servers/Servlet Containers
 Apache Tomcat (Open Source)
– http://jakarta.apache.org/tomcat/
 Jetty (Open Source)
– http://jetty.mortbay.org/jetty/index.html
 Bajie (free)
– http://www.geocities.com/gzhangx/websrv/
– Created by student at University of Texas – Dallas
 Various third-party servlet containers for various web
servers
– http://java.sun.com/products/servlet/industry.html
Tomcat Servlet Container
 Can run as standalone web server
 Can serve static HTML as well as dynamic
JSP content
Installing and Running Tomcat 4.1.18
 Download <jakarta-tomcat-4.1.18.zip> from
http://jakarta.apache.org/builds/jakartatomcat-4.0/release/v4.1.18/bin/
 Using WinZip (or some other similar tool)
extract contents to C:\ (or wherever you
choose)
 Set environmental variables (see handout)
 Start it up! (see handout)
 Check to see that it was installed properly
(see handout)
Additional JSP Resources
 JSP Tutorial
– http://developer.java.sun.com/developer/onlineTraining/JSPIntro/
 Java Developer Connection
– http://forum.java.sun.com/
 JavaServer™ Pages
– http://java.sun.com/products/jsp/
 JSP Syntax Reference
– http://java.sun.com/products/jsp/technical.html#syntax
 Google
Questions & Comments?