O'Reilly - Java Server Pages.pdf - JavaServer Pages Hans Bergsten First Edition December 2000 ISBN 1-56592-746-X 572 pages JavaServer Pages shows how to

O'Reilly - Java Server Pages.pdf - JavaServer Pages Hans...

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Unformatted text preview: JavaServer Pages Hans Bergsten First Edition, December 2000 ISBN: 1-56592-746-X, 572 pages JavaServer Pages shows how to develop Java-based web applications without having to be a hardcore programmer. The author provides an overview of JSP concepts and illuminates how JSP fits into the larger picture of web applications. There are chapters for web authors on generating dynamic content, handling session information, and accessing databases, as well as material for Java programmers on creating Java components and custom JSP tags for web authors to use in JSP pages.JavaServer Pages shows how to develop Java-based web applications without having to be a hardcore programmer. The author provides an overview of JSP concepts and illuminates how JSP fits into the larger picture of web applications. There are chapters for web authors on generating dynamic content, handling session information, and accessing databases, as well as material for Java programmers on creating Java components and custom JSP tags for web authors to use in JSP pages. Release Team[oR] 2001 Preface What's in This Book Audience Organization About the Examples Conventions Used in This Book How to Contact Us Acknowledgments 1 i JSP Application Basics 1 Introducing JavaServer Pages 2 HTTP and Servlet Basics 13 JSP Overview 25 4 Setting Up the JSP Environment 34 ii JSP Application Development 5 Generating Dynamic Content 42 6 Using Scripting Elements 55 Error Handling and Debugging 74 Sharing Data Between JSP Pages, Requests, and Users 87 3 7 8 This part of the book describes the fundamentals of HTTP (the protocol used by all web applications), how servlets and JSP are related, and how to set up a JSP development environment and install the book examples. 1.1 1.2 1.3 2.1 2.2 2.3 3.1 3.2 3.3 3.4 4.1 4.2 4.3 4.4 4.5 What Is JavaServer Pages? Why Use JSP? What You Need to Get Started The HTTP Request/Response Model Servlets Packaging Java Web Applications The Problem with Servlets The Anatomy of a JSP Page JSP Processing JSP Application Design with MVC Installing the Java Software Development Kit Installing the Tomcat Server Testing Tomcat Installing the Book Examples Example Web Application Overview 8 The focus of this part of the book is on developing JSP-based web applications using both standard JSP elements and custom components. Through the use of practical examples, you will learn how to handle common tasks such as validating user input, accessing databases, authenticating users and protecting web pages, localizing your web site, and more. 5.1 5.2 6.1 6.2 6.3 6.4 6.5 6.6 7.1 7.2 7.3 8.1 8.2 8.3 8.4 8.5 What Time Is It? Input and Output Java Primer Implicit JSP Objects Conditional Processing Displaying Values Using an Expression to Set an Attribute Declaring Variables and Methods Dealing with Syntax Errors Debugging a JSP-Based Application Dealing with Runtime Errors Passing Control and Data Between Pages Sharing Session and Application Data Using Custom Actions Online Shopping Memory Usage Considerations 9 Database Access 9.1 9.2 9.3 9.4 Accessing a Database from a JSP Page Input Validation Without a Bean Using Transactions Application-Specific Database Actions 109 10 Authentication and Personalization 130 11 Internationalization 148 12 Bits and Pieces 165 10.1 10.2 10.3 11.1 11.2 11.3 11.4 12.1 12.2 12.3 12.4 12.5 12.6 12.7 Container-Provided Authentication Application-Controlled Authentication Other Security Concerns How Java Supports Internationalization and Localization Generating Localized Output A Brief History of Bits Handling Localized Input Buffering Including Page Fragments XML and JSP Mixing Client-Side and Server-Side Code Precompiling JSP Pages Preventing Caching of JSP Pages How URLs Are Interpreted III: JSP in J2EE and JSP Component Development If you're a programmer, this is the part of the book where the real action is . Here you will learn how to develop your own custom actions and JavaBeans, and how to combine JSP with other Java server-side technologies, such as servlets and Enterprise JavaBeans (EJB). 13 Web Application Models 182 14 Combining Servlets and JSP 190 15 Developing JavaBeans for JSP 200 16 Developing JSP Custom Actions 213 17 Developing Database Access Components 235 13.1 13.2 13.3 14.1 14.2 14.3 14.4 15.1 15.2 15.3 16.1 16.2 16.3 16.4 16.5 16.6 16.7 16.8 16.9 16.10 17.1 17.2 17.3 17.4 The Java 2 Enterprise Edition Model The MVC Model Scalability Using a Servlet as the Controller A More Modular Design Using Action Objects Sharing Data Between Servlets and JSP Pages Using a JSP Error Page for All Runtime Errors JavaBeans as JSP Components JSP Bean Examples Unexpected <jsp:setProperty> Behavior Tag Extension Basics Developing a Simple Action Processing the Action Body Letting Actions Cooperate Creating New Variables Through Actions Developing an Iterating Action Creating the Tag Library Descriptor Validating Syntax How Tag Handlers May Be Reused Packaging and Installing a Tag Library Using Connections and Connection Pools Using a Generic Database Bean Developing Generic Database Custom Actions Developing Application-Specific Database Components iv Appendixes A JSP Elements Syntax Reference 260 B JSP API Reference 270 C Book Example Custom Actions and Classes Reference 312 D Web-Application Structure and Deployment Descriptor Reference 337 E JSP Resource Reference 346 Colophon 350 In this part of the book, you find reference material, such as descriptions of JSP elements and classes, all book example components, the web application deployment descriptor, and more. A.1 A.2 A.3 A.4 A.5 B.1 B.2 B.3 B.4 C.1 C.2 C.3 C.4 C.5 D.1 D.2 D.3 E.1 E.2 E.3 Directive Elements Scripting Elements Action Elements Comments Escape Characters Implicit Variables Servlet Classes Accessible Through Implicit Variables Tag Extension Classes Other JSP Classes Generic Custom Actions Internationalization Custom Actions Database Custom Actions Utility Classes Database Access Classes Web Application File Structure Web Application Deployment Descriptor Creating a WAR File JSP-Related Products Web Hosting Information and Specifications JavaServer Pages (JSP) technology provides an easy way to create dynamic web pages. JSP uses a componentbased approach that allows web developers to easily combine static HTML for look-and-feel with Java components for dynamic features. The simplicity of this component-based model, combined with the cross-platform power of Java, allows a web development environment with enormous potential. JavaServer Pages shows how to develop Java-based web applications without having to be a hardcore programmer. The author provides an overview of JSP concepts and discusses how JSP fits into the larger picture of web applications. Web page authors will benefit from the chapters on generating dynamic content, handling session information, accessing databases, authenticating users, and personalizing content. In the programmingoriented chapters, Java programmers learn how to create Java components and custom JSP tags for web authors to use in JSP pages. JavaSercer Pages Preface JavaServer Pages™ (JSP) is a new technology for web application development that has received a great deal of attention since it was first announced. Why is JSP so exciting? One reason is that JSP is Java-based, and Java is well-suited for enterprise computing. In fact, JSP is a key part of the Java™ 2 Enterprise Edition (J2EE) platform and can take advantage of the many Java Enterprise libraries, such as JDBC, JNDI, and Enterprise JavaBeans™. Another reason is that JSP supports a powerful model for developing web applications that separates presentation from processing. Understanding why this is so important requires a bit of a history lesson. In the early days of the Web, the only tool for developing dynamic web content was the Common Gateway Interface (CGI). CGI outlined how a web server made user input available to a program, as well as how the program provided the web server with dynamically generated content to send back. CGI scripts were typically written in Perl. (In fact, CGI Perl scripts still drive numerous dynamic web sites.) However, CGI is not an efficient solution. For every request, the web server has to create a new operating-system process, load a Perl interpreter and the Perl script, execute the script, and then dispose of the entire process when it's done. To provide a more efficient solution, various alternatives to CGI have been added to programmers' toolboxes over the last few years: FastCGI, for example, runs each CGI program in an external permanent process (or a pool of processes). In addition, mod_perl for Apache, NSAPI for Netscape, and ISAPI for Microsoft's IIS all run server-side programs in the same process as the web server itself. While these solutions offer better performance and scalability, each one is supported by only a subset of the popular web servers. The Java Servlet API, introduced in early 1997, provides a solution to the portability issue. However, all these technologies suffer from a common problem: HTML code embedded inside programs. If you've ever looked at the code for a servlet, you've probably seen endless calls to out.println( ) that contain scores of HTML tags. For the individual developer working on a simple web site this approach may work fine, but it makes it very difficult for people with different skills to work together to develop a web application. This is becoming a significant problem. As web sites become increasingly complex and are more and more critical to the success of an organization, the appearance and usability of the web interface becomes paramount. New client technologies, such as client-side scripts and DHTML, can develop more responsive and interactive user interfaces, stylesheets can make it easier to globally change fonts and colors, and images can make the interface more appealing. At the same time, server-side code is getting more complex, and demands for reliability, performance, and fault tolerance are increasing. The growing complexity of web applications requires a development model that allows people with different skills to cooperate efficiently. JavaServer Pages provides just such a development model, allowing web page authors with skills in graphics, layout, and usability to work in tandem with programmers who are experienced in server-side technologies such as multithreading, resource pooling, databases, and caching. While there are other technologies, such as ASP, PHP, and ColdFusion, that support similar development models, none of them offers all the advantages of JSP. What's in This Book This book covers Version 1.1 of the JavaServer Pages specification, which was released in late 1999. In this book, you will learn how to use all the standard JSP elements and features, including elements for accessing JavaBeans components, separating the processing over multiple pages to increase reusability and simplify maintenance, and sharing information between pages, requests, and users. You will also learn how to use and develop custom components. A rich set of custom components, for tasks such as integration of database data, internationalization, access control, and conditional processing, is described in detail. Many of these components are generic enough that you can reuse them directly in your own applications. The examples in this book guide you through solutions to common JSP design problems, from basic issues such as retrieving and validating user input, to more advanced areas such as developing a database-driven site, authenticating users, providing personalized content, and implementing internationalization. The last part of the book describes how you can combine JSP with other Java technologies; in particular, I describe the combination of JSP and servlets and provide an overview of how JSP fits into the larger scope of J2EE. page 1 JavaSercer Pages Audience This book is for anyone interested in using JSP technology to develop web applications. In particular, it is written to help the two types of people commonly involved in the development of a JSP-based application: Page authors Page authors primarily develop the web interface to an application. This group uses HTML, stylesheets, and client-side code to develop a rich user interface, and wants to learn how to use JSP elements in web pages to interact with the server components of the application, such as databases and Enterprise JavaBeans (EJB). Java programmers Java programmers are comfortable with the Java programming language and Java servlets. This group is interested in learning how to develop JSP components that page authors can use in web pages, such as JSP custom actions and JavaBeans, and how to combine JSP with other Java server-side technologies, such as servlets and EJB. This book is structured into three parts, which I describe shortly, to make it easier to find the material you are most interested in. What You Need to Know It's always hard to assume how much you, as the reader, already know. For this book, it was even harder, since the material is intended for two audiences: page authors and programmers. I have assumed that anyone reading this book has experience with HTML; consequently, I will not explain the HTML elements used in the examples. But even if you're an HTML wiz, this may be your first exposure to dynamic web content and web applications. A thorough introduction to the HTTP protocol that drives all web applications, as well as to the concepts and features specific to servlet and JSP-based web applications, is therefore included. If you want to learn more about HTML, I recommend HTML and XHTML: The Definitive Guide, by Chuck Musciano and Bill Kennedy (O'Reilly & Associates). If you're a page author, I have assumed that you don't know anything about programming, although it doesn't hurt if you have played around with client-side scripting languages like VBScript or JavaScript (ECMAScript). This book contains a brief Java primer with enough information to allow you to use a modest amount of Java code in JSP pages. As you will see, I recommend that you use Java components developed by a Java programmer instead of putting your own Java code in the pages, so you don't have to know all the intricate details of the Java language to use JSP. I have assumed that programmers reading this book are familiar with Java programming, object-oriented concepts, and Java servlets. If you plan to develop JSP components for page authors and are not familiar with Java programming, I recommend that you read an introductory Java book, such as Exploring Java by Patrick Niemeyer and Joshua Peck (O'Reilly). If you need to learn about servlets, I recommend Java Servlet Programming by Jason Hunter and William Crawford (O'Reilly) or another book that covers servlet technology. The chapters dealing with database access require some knowledge of SQL and databases in general. I will explain all that you need to know to run the examples, but if you're hoping to develop database-driven applications, you will need to know more about databases than what's in this book. page 2 JavaSercer Pages Organization This book is structured into three parts. The first part describes the fundamentals of HTTP (the protocol used by all web applications), how servlets and JSP are related, and how to set up a JSP development environment. The focus of the second part is on developing JSP-based web applications using both standard JSP elements and custom components. Through practical examples, you will learn how to handle common tasks such as validating user input, accessing databases, authenticating users and protecting web pages, localizing your web site, and more. This portion of the book is geared more towards web content designers. In the third part, you will learn how to develop your own custom actions and JavaBeans, and how to combine JSP with other Java server-side technologies, such as servlets and Enterprise JavaBeans (EJB). This portion of the book is targeted towards the programming community. All in all, the book consists of 17 chapters and five appendixes as follows. Part I, JSP Application Basics Chapter 1 Explains how JSP fits into the big picture of web applications and how it compares to alternative technologies. Chapter 2 Describes the fundamental HTTP and servlet concepts you need to know to use JSP to its full potential. Chapter 3 An overview of the JSP features, as well as the similarities and differences between JSP pages and servlets. Also introduces the Model-View-Controller design model and how it applies to JSP. Chapter 4 Describes where to get the JSP reference implementation, Apache Tomcat, and how to set it up on your system. Also explains how to install the book examples. Part II, JSP Application Development Chapter 5 Explains how to use JSP to generate dynamic content and how to receive and validate user input. Chapter 6 A brief introduction to Java programming, followed by descriptions of all the JSP elements that let you embed Java code directly in your JSP pages. Chapter 7 Describes the kinds of errors you may encounter during development of a JSP-based application, and strategies and JSP features that help you deal with them. Chapter 8 Explains the JSP features that let you separate different types of processing in different pages to simplify maintenance and further development. Also describes how sessions can be used to build up information over a sequence of requests from the same user, and how information that applies to all users can be shared using the application scope. page 3 JavaSercer Pages Chapter 9 A quick overview of relational databases, JDBC, and SQL basics. Introduces a set of generic custom actions for reading, updating, and deleting database data. Chapter 10 Describes how authentication and access control can be implemented using container-provided and application-controlled mechanisms, and how to use information about the current user to personalize the web pages. Chapter 11 Explains internationalization and localization, as well as the Java features available to implement an internationalized application. Describes a set of custom actions used to implement a web site with support for multiple languages. Chapter 12 Covers various areas not discussed in previous chapters, such as using XML and XSL with JSP, combining JSP with client-side code, reusing JSP fragments by including them in JSP pages, precompiling JSP pages, and more. Part III, JSP in J2EE and JSP Component Development Chapter 13 An overview of J2EE and web application architectures using JSP in combination with other Java technologies. Chapter 14 Describes in detail how JSP can be combined with servlets. Chapter 15 Provides details about JavaBeans as they relate to JSP, including threading and synchronization concerns for session and application-scope JavaBeans, as well as how using JavaBeans can make it easier to eventually migrate to an EJB architecture. The beans used in previous chapters are reused as examples. Chapter 16 Describes the JSP Tag Extension mechanism and how it is used to develop custom actions, reusing many of the custom actions from previous chapters as examples. Chapter 17 Describes the database-access custom actions used in the previous chapters and how to use them with both connection pools developed in-house and those provided by a third-party vendor. Also explains how you can reuse the database-access beans to develop your own application-specific database custom actions. page 4 JavaSercer Pages Part IV, Appendixes Appendix A Contains descriptions of all the standard JSP 1.1 elements. Appendix B Contains descriptions of all implicit objects available in a JSP page as defined by the servlet and JSP APIs, as well as the tag extension mechanism classes and interfaces. Appendix C Contains descriptions of the custom actions, beans, and utility classes used in the examples. Appendix D Contains descriptions of the standar...
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