Basic Java Servlet/JSP Web
Development
David Lucek
Lucek Consulting
www.lucek.com
dave@lucek.com
May 13th, 2003
@2003 Lucek Consulting
Download the Sample Application
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Download from www.lucek.com, select the
downloads tab
Includes the full source
Unzip to c:\ drive or $HOME/lucek
May 13th, 2003
What is a Servlet?
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Java Servlets/JSP are part of the Sun’s J2EE
Enterprise Architecture
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Java Servlet
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The web development part
is a simple, consistent mechanism for extending the
functionality of a web server
Are precompiled Java programs that are executed on the
server side.
Require a Servlet container to run in
Latest Servlet Spec is 2.3
May 13th, 2003
What is a Java Server Page (JSP)
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Java Server Pages (JSP)
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A simplified, fast way to create dynamic web content
HTML or XML pages with embedded Java Code or
Java Beans
Can be a mix of template data in HTML/XML with
some dynamic content
A JSP is a complied to a Java Servlet automatically
by the Servlet container, it is then cached
Latest JSP Spec is 1.2
May 13th, 2003
Why Use Servlets?
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Work well in a Heterogeneous Environments
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OS and platform neutral
Work with all major web servers (IIS, Apache,etc..)
Well defined Web Architecture framework
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Standard built in services such as:
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Standard Approach to Authentication using declarative security
vice programmatic security
Database connection pooling
Complete support for sessions via cookies and/or URL re-writing
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Has automatic fallback to URL re-writing
May 13th, 2003
Why Use Servlets Con’t?
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Robust Object-Orientated API in Java language
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Ever try to maintain a large ASP, Perl, or PHP site 
Clean separation of Controller/Logic from
Presentation
Efficient, scales very well
There are good free Servlet/JSP containers
and connectors
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That run under both UNIX and win32
May 13th, 2003
J2EE Web Application Components
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Java Servlets
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JSP pages, normally for Presentation
Java Beans
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Extend off of HttpServlet
Normally used as value objects, pass to data to JSPs
Tag Libraries – XML based JSP elements
Web Deployment Descriptor
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/web-inf/web.xml
May 13th, 2003
Web Deployment Descriptor
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/web-inf/web.xml
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Part of the standard
Defines servlets used in the web application
Maps servlets to URLs
A servlet can map to many URLs
Defines resources available to the web app
Defines security constraints
Defines other stuff like
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Welcome file list
Session timeout
Error page mapping
May 13th, 2003
J2EE Web Directory Structure 1
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Top Directory is normally the context Path
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/tomcat/webapps/servletdemo
Normally, the URL would be http://localhost:8080/servletdemo
Contains JSP and other static content plus the web-inf
directory
/web-inf directory
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This is a protected directory, can not point browser to any file
in this directory
/classes – unpacked web application classes, auto-magically
added to CLASS_PATH
/lib – web application JAR files
/taglib – tag library descriptor files
May 13th, 2003
J2EE Web Directory Structure 2
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/web-inf/web.xml
/web-inf/*
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Would normally put any static or JSP files here
Protects them from Direct Invocation
Always best to call a JSP through a servlet first
May 13th, 2003
JSP Constructs 1
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Used in JSP pages, pages that end *.jsp
Comment <%-- Comment --%>
Declaration <%! int x = 0; %>
Expression <%= expression %>
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Outputs to the Response stream
Like a “printf” to the browser
Do NOT use semi-colon to terminate the line
Scriplets - contains Java Code
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<% code fragments %>
May 13th, 2003
JSP Constructs 2
<% if (value.getName().length != 0) { %>
<H2>The value is: <%= value.getName() %></H2>
<% } else { %>
<H2>Value is empty</H2>
<% } %>
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Implicit objects always available in the JSP Page
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“request” – Browser’s Request Object
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Use to get HTTP headers, length etc..
“response” - HttpResponse Object
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JSP Constructs 3
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“session” – internal HttpSession Object
“pageContext”
“application”
“out”, same as <%= %>
“config” – servlet configuration
“page”
“exception”
JSP Directives
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Are messages or instructions to the JSP container
May 13th, 2003
JSP Constructs 4
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Do not produce any output
“page” directive
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“include” directive
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<%@ page import=“com.lucek.*” %>
Commonly used for importing class paths
<%@ include file=“header.htm” %>
Good for including static content
“taglib” – lists the tag library descriptor location
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Required when using tab libraries
May 13th, 2003
Java Beans as Used in Web Apps
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Normally used for all data transfers and business
components
Similar to how Java Beans are used in Swing and
AWT
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But do not need the full implementation
Must have no constructor or no-arg constructor
Must have setter and getter methods for each property
value
JSP constructs/tags use Java Beans
May 13th, 2003
JSP Actions
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JSP actions are special tags that affect the
output stream and are normally used with Java
beans
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Most commonly used:
<jsp:useBean>, <jsp:getProperty>, <jsp:setProperty>
 The code below will display the lastName property of the
student bean on the output stream
<jsp:useBean id="student" scope="request"
class="com.lucek.dto.StudentValue" />
<jsp:getProperty name="student" property="lastName" />
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May 13th, 2003
Servlet Container/Engine
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Servlets/JSP require a Container
Apache Tomcat is the reference implementation of the
Servlet/JSP Specs
It is open source, small, install quickly,and is FREE
Latest Version is 4.1.24
Web Site: jakarta.apache.org/tomcat
It include a simple HTTP 1.1 server, good enough for
development and small intranets.
May 13th, 2003
Tomcat Install
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Requires a JDK, get 1.4.1 and install into c:\jdk
or $HOME/jdk
Add JAVA_HOME to your environment and the
“bin” directory to your PATH
Good practice to unpack into c:\tomcat or
$HOME/tomcat
Add CATALINA_HOME to your environment
and the “bin” directory to your PATH
May 13th, 2003
Tomcat Directory Structure
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Everything is relative to $CATALINA_HOME
/bin – Startup/shutdown scripts
/conf
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/common – common class and jar files used by Tomcat
and web applications
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Server.xml – main configuration file
Put JDBC drivers here
/server – class and jar files used by Tomcat internally
/shared – class and jar files for all web applications
/webapps – This is where you put your web application
in a sub-directory or external context file.
May 13th, 2003
Starting Tomcat
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/bin/startup.bat or startup.sh
Point Browers to http://localhost:8080, should
see default page
All the Docs are there on the default page!
Check out the examples pages, good tutorials
May 13th, 2003
Other Development Tools 1
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Ant Build Tool
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Standard Java Build tool
Basic on UNIX make, but much better
Site: http://ant.apache.org
Install in c:\ant or $HOME/ant
Java IDE
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Try NetBeans, it is nice
Tomcat is built in, but is an older version
Includes full Servlet and JSP debugging
Site: www.netbeans.org
May 13th, 2003
Other Development Tools 2
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Junit
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Standard Automated Unit Testing Tool
Site: http://junit.sourceforge.net
Jedit
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Slick Programmer’s Editor
Written in Java
Site: jedit.org
May 13th, 2003
Simple Servlet Application 1
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See “servletdemo” code
Mount the servletdemo, servletdemo/java/src, and
servletdemo/web in NetBeans Explorer Tab
For a Hello World Servlet look at:
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Java/src/com/lucek/action/HelloWorld.java
To build and run
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$ cd servletdemo
Setup the proper build variables in the build.properties file
$ ant all
$ ant deploy
Point your browsers at http://localhost:8080/servletdemo
May 13th, 2003
Simple Servlet Application 2
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Look at the web.xml file and how the same
servlet can be mapped to many URLs
Look at SimpleBean.java which should how to
pass a Java Bean to a JSP page
Look at the different ways a bean’s value can
be obtained in the EditStudent.jsp
May 13th, 2003
Best Practices/Patterns
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Always Separate out the logic from the presentation
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Have a clean separation between your data access
and controller layers (DAO)
Always use DTO or value object
Use a Model-View-Controller Architecture
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Use servlets for the logic/controller and JSP’s for presentation
Ideally should never have Java Code in the JSP page
Do not write it, use Struts
Site: jakarta.apache.org/struts/
Use Unit tests
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Junit Automation via Ant build tasks
May 13th, 2003
What we have not talked about
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All the specific Servlet APIs
Tag libraries
Sessions, cookies
JDBC service support from the container
Container based authentication
Lots of other stuff
May 13th, 2003
Next Presentation?
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Create a data driven web site using MySql and
Servlets/JSP
Setup Authentication Realm with declarative
security
Setup JDBC connection pooling
Struts?
May 13th, 2003