Database. Request Class. jdbc. Servlet. Result Bean. Response JSP. JSP and Servlets. A Comprehensive Study. Mahesh P. Matha

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1 Database Request Class Servlet jdbc Result Bean Response py Ki ta b JSP Ko JSP and Servlets A Comprehensive Study Mahesh P. Matha

2 JSP and Servlets A Comprehensive Study Mahesh P. Matha Assistant Professor Department of Computer Science (Post-Graduate section) Parvatibai Chowgule College of Arts and Science Margao, Goa Delhi

3 JSP and Servlets: A Comprehensive Study Mahesh P. Matha 2013 by PHI Learning Private Limited, Delhi. All rights reserved. No part of this book may be reproduced in any form, by mimeograph or any other means, without permission in writing from the publisher. ISBN The export rights of this book are vested solely with the publisher. Published by Asoke K. Ghosh, PHI Learning Private Limited, Rimjhim House, 111, Patparganj Industrial Estate, Delhi and Printed by Mohan Makhijani at Rekha Printers Private Limited, New Delhi

4 To My nephews and nieces

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6 Contents Preface xiii Acknowledgements xvii 1. HTTP and JSP-Servlet Technology 1 8 Chapter at a Glance Introduction to HTTP HTTP Request Structure Request Line or More Headers The Empty Line The Message Body HTTP Response Structure Status-Line or More Headers The Empty Line Message Body HTML, Client-side and Server-side Scripting HTML Client-side Scripting Server-side Scripting JSP-Servlet Technology Installing, Configuring and Testing the Java Development Kit (JDK) Installing, Configuring and Testing the Apache Tomcat Server 6 Summary 7 Review Questions 8 v

7 vi Contents 2. JSP and Servlets: an overview 9 18 Chapter at a Glance Introduction An Overview of JSP JSP Hello World Program Development Introduction to Java Servlets Servlet Hello World Program Development 15 Summary 17 Review Questions Components of a JSP Chapter at a Glance Introduction Expressions Scriptlets and Comments Declarations Directives The page Directive The include Directive The taglib Directive JSP Standard Actions The <jsp:usebean> Action The <jsp:forward> Action The <jsp:include> Action The <jsp:param> Action The <jsp:plugin>, <jsp:params> and <jsp:fallback> Actions tags Escaping Characters Internal Handling of JSP Components 68 Summary 72 Review Questions Implicit ObjecTS of JSP Chapter at a Glance Introduction Implicit Objects The request object The response object The session object The application object The out object The exception object The config object 106

8 Contents vii 4.10 The page object The pagecontext object 109 Summary 112 Review Questions Servlets and Session Tracking mechanisms Chapter at a Glance Introduction javax.servlet Package Servlet Interface The ServletConfig Interface The GenericServlet Class javax.servlet.http Package HttpServlet Class Session Tracking Cookies URL Rewriting Hidden Fields Session Tracking with Cookies Session Tracking with URL Encoding 138 Summary 143 Review Questions Application event Listeners Chapter at a Glance Introduction ServletContextListener Interface ServletContextAttributeListener Interface HttpSessionListener Interface HttpSessionAttributeListener Interface HttpSessionBindingListener Interface HttpSessionActivationListener Interface ServletRequestListener Interface ServletRequestAttributeListener Interface 165 Summary 170 Review Questions Filters Chapter at a Glance Introduction to Filters What is a Filter? Life Cycle of a Filter Uses of a Filter Benefits of Using a Filter 174

9 viii Contents 7.2 Filter, FilterChain and FilterConfig Interfaces Configuring Filters Chaining Filters Wrapping Requests and Responses 186 Summary 193 Review Questions The expression language Chapter at a Glance Introduction to the Expression Language (EL) EL Expressions and Literals Extracting Property Values EL Implicit Objects and Variables EL Operators Arithmetic Operators Relational Operators Logical Operators Conditional Operator Empty Operator Precedence of Operators Reserved Words in EL Functions in EL 209 Summary 212 Review Questions The JSTL Core Tags and functions Chapter at a Glance Introduction to JSTL <c:out> Tag <c:set> Tag <c:remove> Tag <c:catch> Tag <c:if> Tag <c:choose>, <c:when> and <c:otherwise> Tags <c:foreach> Tag <c:fortokens> Tag <c:param> Tag <c:import> Tag <c:url> Tag <c:redirect> Tag JSTL Functions 242 Summary 245 Review Questions 245

10 Contents ix 10. JSP, xml and THe JSTL XML Tags Chapter at a Glance Introduction to XML Document Object Model (DOM) Parsing XML Using DOM Parser Simple API for XML (SAX) Parsing XML Using SAX Parser XSL Transformation with XSLT Fundamentals of XSL and XSLT Classes and Interfaces for Transformation JSTL XML Tags The <x:parse> and <x:out> Tags The <x:foreach> and <x:set> Tags The <x:if> Tag The <x:choose>, <x:when> and <x:otherwise> Tags The <x:transform> and <x:param> Tags 276 Summary 278 Review Questions JSP, databases and The JSTL SQL Tags Chapter at a Glance Installing and Configuring the MySQL DBMS A Review of SQL Statements in MySQL DDL Statements DML Statements Linking MySQL with JSP Inserting a Record Updating an Existing Record Deleting a Record The JSTL SQL Tags The <sql:setdatasource> Tag The <sql:update> Tag The <sql:param> Tag The <sql:query> Tag The <sql:transaction> Tag The <sql:dateparam> Tag 323 Summary 326 Review Questions The JSTL FormaTTing Tags Chapter at a Glance Introduction Locales, ResourceBundles and TimeZones 329

11 x Contents 12.3 Internationalization and Localization Why is Internationalization and Localization Needed? How to Achieve Internationalization? <fmt:setlocale> Tag <fmt:bundle> Tag <fmt:message> Tag <fmt:setbundle> Tag <fmt:param> Tag <fmt:requestencoding> Tag <fmt:timezone> Tag <fmt:settimezone> Tag <fmt:formatnumber> Tag <fmt:parsenumber> Tag <fmt:formatdate> Tag <fmt:parsedate> Tag 376 Summary 381 Review Questions An introduction To custom Tags Chapter at a Glance Custom Tags Developing a Custom Tag without any Body Developing a Custom Tag with Attributes Developing a Custom Tag with Body Developing a Custom Tag that Evaluates its Body Repeatedly Developing a Custom Tag that Modifies its Body Co-operating Custom Tags Developing a Custom Tag with Scripting Variables 409 Summary 412 Review Questions Simple Tag extensions, JSP fragments and Tag files Chapter at a Glance Introduction JspFragment Class The SimpleTag Interface and the SimpleTagSupport Class The SimpleTag Interface The SimpleTagSupport Class Developing Custom Tags using SimpleTagSupport Class Tag without any Body Tag with Attributes Tag with a Body 421

12 Contents xi Tag that Evaluates its Body Repeatedly Tag that Modifies its Body Tag Files Tag File Directives Tag File Standard Actions <jsp:invoke> Action <jsp:dobody> Action Tag File Usage Invoking JSP Fragments 431 Summary 433 Review Questions 434 Glossary Index

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14 Preface JavaServer Pages (JSP) and Servlets technology is being widely used in the field of Information Technology to develop Web Applications. The aim of writing this book is to assist the reader to make a comprehensive and detailed study of this technology. Organisation of the Book The book provides 14 chapters which can be summarized as follows. Chapter 1 is an introduction to HyperText Transfer Protocol (HTTP), describing the HTTP request and HTTP response structures. It elaborates on HyperText Markup Language (HTML) and explains the meaning of client-side and server-side scripting. It introduces the reader to JSP and Servlet technology and explains the process of installation, configuration and testing of Java Development Kit (JDK) and the Apache Tomcat Server. Chapter 2 discusses the fundamentals of JavaServer Pages and Servlets. In this chapter the steps of coding a JSP, placing it in a specific directory and requesting it via a browser are discussed. A detailed explanation about the translation of a JSP into a servlet, the presence of the servlet in a specific folder, its compilation to byte code and loading and creation of a single servlet instance is provided. The explanation is done with the help of the Hello World program that is written using a JSP. Next, the discussion focuses on the coding of a generic servlet with the help of the Hello World program that is written using a servlet. The steps of writing the servlet, placing it in an appropriate directory, mapping it and finally requesting it, are discussed. Chapter 3 introduces the reader to the various components of a JSP. The components include expressions, scriptlets, comments, declarations, directives and standard actions. It also discusses the escaping of characters and the internal handling of various JSP components. Chapter 4 elucidates on the various implicit objects of JSP. The implicit objects include the request, response, session, application, out, exception, config, page and pagecontext. Chapter 5 deals with two topics namely Servlets and Session Tracking. As part of the discussion of the first topic, the Servlet and ServletConfig interfaces and the GenericServlet class of the javax.servlet package are discussed. This is followed by a discussion of the HttpServlet xiii

15 xiv Preface class that is present in the javax.servlet.http package and demonstration of a HTTP servlet. As part of the discussion of the second topic, the concepts of cookies, URL rewriting and hidden fields are elaborated upon. Lastly the tracking of sessions by using cookies as well as by using URL encoding is explained. Chapter 6 discusses the different types of Application Event Listeners. Chapter 7 discusses the concept of a filter, its life cycle, uses and benefits. This is followed by a discussion on the Filter, FilterChain and FilterConfig interfaces. Next, the configuration and chaining of filters is discussed. Lastly, the wrapping of requests and responses is explained. Chapter 8 begins by introducing the reader to the Expression Language (EL). This is followed by a discussion on EL expressions and literals, extraction of property values, EL s implicit objects, variables, operators, reserved words and EL functions. Chapter 9 introduces the reader to the JSP Standard Tag Library (JSTL), discussing the JSTL core tags and the JSTL functions. Chapter 10 begins with an introduction of XML, followed by a discussion on the Document Object Model and the parsing of XML using the DOM parser. Similarly, the Simple API for XML (SAX) API; the SAX parser; the XSL transformation with XSLT are discussed followed by the JSTL XML tags. Chapter 11 discusses the steps required to install MySQL DBMS, reviews the SQL statements in MySQL and discusses the linking of JSP and MySQL. Then the insert, delete and update operations are demonstrated by using Java code within a JSP. Lastly, the JSTL SQL tags are discussed. Chapter 12 introduces the reader to locales, resource bundles and time zones and discusses internationalization and localization and their necessity. It also discusses each of the JSTL formatting tags. Chapter 13 discusses the classic custom tags; the Tag; IterationTag; BodyTag interfaces as well as the TagSupport and BodyTagSupport classes are discussed. It explains the development of classic tags without a body, with attributes, with a body, with repeated body evaluation, with body modification, co-operating tags and the development of custom tags with scripting variables. Chapter 14 deals with two topics, namely development of tags using the SimpleTagSupport class and the Tag files. It discusses the JspFragment class, the SimpleTag interface and the SimpleTagSupport class. It explains the development of simple tags without a body, with attributes, with body, with repeated body evaluation and with body modification. Lastly this chapter elaborates on tag files. The Tag File Directives, Standard Actions, Tag file usage and Fragment invocation are discussed. Features of this Book I have written this book in a simple and straightforward language. This will make it easier for the reader to comprehend the topics that are covered in this book. I have covered and illustrated the topics exhaustively and in minute detail. Certain books just describe a particular topic and do not illustrate it with examples. The reader is compelled to refer to other books or websites to search for the explanation. In my book, when a topic is discussed, it is illustrated with the help of

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