tutorial: server-side web applications with java, jsp and tomcat

Tutorial: Tutorial: Server-Side Web Applications with Server-Side Web Applications with

Java, JSP and TomcatJava, JSP and Tomcat

Eran TochDecember 2004

Methodologies in Information Systems Development

Server-Side Web Applications with Java, JSP and Tomcat – Eran TochMethodologies in Information System Development

2

AgendaAgenda• Introduction and architecture• Installing Tomcat• Building a Web Application (through Eclipse)• The Phones Web Application

– Writing JavaBeans – Writing JSPs

• Includes, session and application• Model 2 Architecture


3

Web Application vs. Web SiteWeb Application vs. Web Site

Mainframe

Data

WebService

Web Site Web Application


4

The Difference – cont’dThe Difference – cont’d

Web sites are– Static– File based– May include client’s JavaScript code

• Web Applications are– Dynamic (output depend on input)– Database based– Multi-layered– Session dependent (most of the times)– Personalized (some of the times)


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JSP

Java Web Application ArchitectureJava Web Application Architecture

Application Server

Browser

Servlet

Java Classes/ EJB

HTTP / HTML

DB / ERP / Legacy


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Tomcat InstallationTomcat Installation

• Go to: http://jakarta.apache.org/tomcat/• Download the latest version (currently 5.5.4)

by going to: Downloads -> Binaries -> Tomcat 5.5.4. – For Windows, download the exe version – with a

Windows setup. The direct link: http://apache.fresh.co.il/jakarta/tomcat-5/v5.5.4/bin/jakarta-tomcat-5.5.4.exe

– For Linux, read the setup manual: http://jakarta.apache.org/tomcat/tomcat-5.5-doc/setup.html

http://jakarta.apache.org/tomcat/

http://apache.fresh.co.il/jakarta/tomcat-5/v5.5.4/bin/jakarta-tomcat-5.5.4.exe

http://apache.fresh.co.il/jakarta/tomcat-5/v5.5.4/bin/jakarta-tomcat-5.5.4.exe


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Tomcat and Java 5Tomcat and Java 5

• Please note that Tomcat v. 5.5.4 requires J2SE 1.5 (also known as J2SE 5) or above.

• If you want to use J2SE 1.4, download Tomcat 5.0.+


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Tomcat Installation – cont’dTomcat Installation – cont’d

If you want Tomcat to startup every time the computer is rebooted, check the “service” option. If you wish to use Tomcat for only for development, it’s best to leave the service option unchecked.


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Tomcat Installation - PortTomcat Installation - Port

You can configure the port that Tomcat will be using. If you want it to be available publicly (behind firewalls etc), change the default port to 80. Otherwise, leave it as it is (880). You can always change it later, in the [TOMCAT_HOME]/conf/server.xml configuration file.


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Running TomcatRunning Tomcat

• Start Tomcat by running Tomcat monitor (Start Menu -> Apache Tomcat -> Monitor Tomcat), and click on Start.

– Point your browser to: http://localhost:8080. If Tomcat works, you should see something like this

– If not, check out the logs (C:\[TOMCAT_HOME]\logs\stdout) and see what went wrong.

http://localhost:8080/


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Managing TomcatManaging Tomcat

• Go to the management console by clicking on the “management” link in the Tomcat root homepage, or directly by going to: http://localhost:8080/manager/html.

• The default username is “admin”, and the default password is ””

• You can change it by changing the [TOMCAT_HOME]\conf\tomcat-users.xml.

http://localhost:8080/manager/html










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Managing Tomcat ConsoleManaging Tomcat Console

Web Application management

Number of current sessions

Start, stop, restart and un-deploy applications


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Building A Web ApplicationBuilding A Web Application

• Build the following folder structure under [TOMCAT-HOME]\webapps

Tomcat-home

confcommonwebapps ...

phones

WEB-INF

lib

classes

jsp

This is the hard way…There are

better


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Creating JSP Project in EclipseCreating JSP Project in Eclipse

1. Open a project for the JSP pages

2. Choose the type “Simple project”


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Creating JSP Project – cont’dCreating JSP Project – cont’d

• Choose the path to the jsp folder

• Click “Finish”


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Creating Java Classes ProjectCreating Java Classes Project

• Create a new project

• Choose “Java Project”


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Creating Java Project – cont’dCreating Java Project – cont’d

• Choose the path to the WEB-INF/classes folder


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Creating Java Project – cont’dCreating Java Project – cont’d

• Make sure the output build path is in the WEB-INF classes folder

• Necessary libraries could be added now


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Better waysBetter ways

• Download MyEclipse IDE extension from:http://www.myeclipseide.com/

• Download Lomboz plugin for Eclipse at: http://www.objectlearn.com/index.jsp

• Both of these plugins will give you:– Easier deployment of projects– JSP debugging– JSP error detection (important!)

http://www.myeclipseide.com/

http://www.objectlearn.com/index.jsp


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Our “Phones” ApplicationOur “Phones” Application

• Simple application that displays phone records from the database

• (stupid, shameless) Architecture:

select_entry.jsp display_phone.jsp

PhoneEntry.java

DBConnector.javaDatabase


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PhoneEntry.javaPhoneEntry.javapackage edu.technion.methodologies.phones; public class PhoneEntry {

private int id = 0;private String name;private String phone;private String email;

public void load(int id) {DBConnector.loadPhone(id, this);

}public void save() {

if (id == 0) {id = DBConnector.insertPhone(this);

}else {

DBConnector.updatePhone(id, this);}

}//getters and setters…

}


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DBConnector.javaDBConnector.java

• See the advanced Java tutorial…


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Writing Scriplets in JSPWriting Scriplets in JSP

• Write HTML as normal• Dynamic parts between <% %> • Eg

<HTML> <BODY> Hello! The time is now <%= new java.util.Date() %> </BODY>

</HTML>


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JSP Scripting ElementsJSP Scripting Elements

• Expressions <%= expression %> • evaluated and inserted into the output

• Scriptlets <% code %> • inserted into the servlet's service method

• Declarations <%! code %> • inserted into the body of the servlet class, outside of

any existing methods


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JSP DirectivesJSP Directives

• There are two main types of directive: – page

• lets you do things like import classes, customize the servlet superclass etc

– Include• lets you insert a file into the servlet class at the time the

JSP file is translated into a servlet.

• <%@ directive attribute="value" %>


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select_entry.jspselect_entry.jsp<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><HTML><HEAD><TITLE>Phones Application</TITLE></HEAD>

<BODY><form action="display_phone.jsp" method="post"><table border=0>

<tr><td>ID: </td><td><input type="text" name="id"></td>

</tr><tr>

<td> </td><td><input type="submit"></td>

</tr></table> </form></BODY></HTML>

HTML Header

HTML form

Nested HTML table structure

HTML text input


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select_entry.jsp – the HTML outputselect_entry.jsp – the HTML output


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display_phone.jspdisplay_phone.jsp<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><%@page import="edu.technion.methodologies.phones.*" %><HTML><HEAD><TITLE>Phone Entry</TITLE></HEAD>

<BODY><%String idParam = request.getParameter("id");int id = 0;if (idParam != null){id = Integer.parseInt(idParam);}PhoneEntry phoneEntry = new PhoneEntry();phoneEntry.load(id);%>

Handling the request

Creating the JavaBean

Importing libraries


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display_phone.jsp – cont’ddisplay_phone.jsp – cont’d

<table border=0><tr>

<td>Name:</td><td><b><%= phoneEntry.getName() %></b></td>

</tr><tr>

<td>Phone:</td><td><%= phoneEntry.getPhone() %></td>

</tr><tr>

<td>Email:</td><td><%= phoneEntry.getEmail() %></td>

</tr></table> </BODY></HTML>


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display_phone.jsp – the HTML Outputdisplay_phone.jsp – the HTML Output


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JSP IncludeJSP Include

• Inserting elements into the JSP page in complication time

<table border="0" width="100%" cellpadding="4"><tr bgcolor="99CCFF"><td><a href="select_entry.jsp">home</a></td></tr></table>

Included JSP file


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JSP Include – cont’dJSP Include – cont’d

…<BODY><%@include file="header.jsp"%><%…

We add the include declarative into display_phone.jsp

And we get:


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Session and Application ObjectsSession and Application Objects• A session is an object associated with a visitor. • Data can be put in the session and retrieved from it

• Sessions are timed-out – the default is ~25 minutes• The application object is accessed similarly, but is unique and global for the web application

//Setting an object within the sessionsession.setAttribute("last_searched_id", new Integer(id));

//Getting an object from the sessionInteger lastID = (Integer)session.getAttribute("last_searched_id");out.println(lastID);


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Advanced IssuesAdvanced Issues

• Servlets – have many advantages over JSP– Inheritance– Class structure

• Tag libraries• Enterprise Java Beans• J2EE Frameworks (WebLogic, Web Sphere,

JBoss)


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Model 2 ArchitectureModel 2 Architecture

• recommended approach for designing medium- and large-sized Web applications

• An implementation of the Model-View-Controller (MVC) pattern

• Applications have 3 layers– Model: containing all data and operations

» JSP classes or beans – View: creating various presentations

» JSP – focus on static data– Controller: receiving requests, updating the model,

and delegating to views » servlet


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Model 2 Architecture – cont’dModel 2 Architecture – cont’d

.jsp

.jsp Form re

quest

forward

Databaseclassesservlet

VIEW CONTROLLER MODEL


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StrutsStruts

• Struts is an open source framework created within the Jakarta project by the Apache Software Foundation

• Supports Model-View-Controller (MVC) design pattern

• http://struts.apache.org/

http://struts.apache.org/


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ReferencesReferences

• Core Servlets and JavaServer Pages, Vol. 1: Core Technologies, Second Edition, by Marty Hall, Larry Brown

• Sun’s JSP Tutorial:http://java.sun.com/j2ee/tutorial/1_3-fcs/doc/JSPIntro.html

• JavaBeans Tutorial:http://java.sun.com/j2ee/tutorial/1_3-fcs/doc/JSPBeans.html

• A set of advanced (and untidy) tutorials:http://www.coreservlets.com/

http://java.sun.com/j2ee/tutorial/1_3-fcs/doc/JSPIntro.html

http://java.sun.com/j2ee/tutorial/1_3-fcs/doc/JSPIntro.html

http://java.sun.com/j2ee/tutorial/1_3-fcs/doc/JSPBeans.html

http://java.sun.com/j2ee/tutorial/1_3-fcs/doc/JSPBeans.html

http://www.coreservlets.com/

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