Java Server Pages

Example Web Application Overview

The examples for this book are packaged as a standard Java web application, as described in Chapter 2. This file structure is supported by all Servlet 2.2-compliant servers, so you can use the example application as a guide when you create your own web applications. How a web application is installed is not defined by the specification, however, so it varies between servers. With Tomcat, you simply copy the file structure to the special webapps directory and restart the server. To modify the configuration information for an application, you need to edit the application’s WEB-INF/web.xml file using a text editor. Other servers may offer special deployment tools that copy the files to where they belong and let you configure the application using a special tool, such as web-based forms.

If you look in the ora web application directory, you’ll see that it contains an index.htm l file and a number of directories corresponding to chapters in this book. These directories contain all the example JSP and HTML pages.

There’s also a WEB-INF directory with a web.xml file, a lib directory, a classes directory, and a tlds directory:

• The web.xml file contains configuration information for the example application in the format defined by the Servlet 2.2 specification. It’s too early to look at the contents of this file now; we will return to parts of it when needed.

• The lib and classes directories are standard directories, also defined by the Servlet 2.2 specification. A common question asked by people new to servlets and JSP (prior to the standard web application format) was, “Where do I store my class files so that the server can find them?” The answer, unfortunately, differed depending on which implementation was used. With the standard web application format, however, it’s easy to answer this question: if the classes are packaged in a JAR file, store the JAR file in the lib directory; otherwise, use the classes directory (with subdirectories mirroring the classes’ package structure). The server will always look for Java class files in these two directories.

• The lib directory for the example application contains five JAR files. The orataglib_1_0.jar file contains all the Java class files for the custom actions and beans used in this book. The jdbc20_stdext_classes.jar file contains classes that are part of the JDBC 2.0 Standard Extension and are used in the database examples. The xalan.jar, xerces.jar, and xsl.jar contain XML parser classes used for an example in Chapter 12.

• The classes directory contains the class for a servlet used to display the raw source code for the example JSP pages, so you can see what they look like before they are processed by the server. It also contains .properties files containing localized text for the example in Chapter 11.

• The tlds directory is not defined by the Servlet 2.2 specification, but is the name used by convention for Tag Library Descriptor (TLD) files. Don’t worry about what this means now. As you read through this book, it will become clear.

If you want to try out some of your own JSP pages, beans, and custom actions while reading this book, simply add the files to the example application structure: JSP pages in any directory except under WEB-INF, and Java class files in either the classes or the lib directory, depending on if the classes are packaged in a JAR file or not. If you want to use the book’s custom actions and beans in another application, copy the files in both the lib and tlds directories to the web application structure for the other application.