Learning Java, 4th Edition

WAR Files and Deployment

As we described in the introduction to this chapter, a WAR file is an archive that contains all the parts of a web application: Java class files for servlets and web services, JSPs, HTML pages, images, and other resources. The WAR file is simply a JAR file (which is itself a fancy ZIP file) with specified directories for the Java code and one designated configuration file: the web.xml file, which tells the application server what to run and how to run it. WAR files always have the extension .war, but they can be created and read with the standard jar tool.

The contents of a typical WAR might look like this, as revealed by the jar tool:

    $ jar tvf shoppingcart.war

        index.html
        purchase.html
        receipt.html
        images/happybunny.gif
        WEB-INF/web.xml
        WEB-INF/classes/com/mycompany/PurchaseServlet.class
        WEB-INF/classes/com/mycompany/ReturnServlet.class
        WEB-INF/lib/thirdparty.jar

When deployed, the name of the WAR becomes, by default, the root path of the web application—in this case, shoppingcart. Thus, the base URL for this web app, if deployed on http://www.oreilly.com, is http://www.oreilly.com/shoppingcart/, and all references to its documents, images, and servlets start with that path. The top level of the WAR file becomes the document root (base directory) for serving files. Our index.html file appears at the base URL we just mentioned, and our happybunny.gif image is referenced as http://www.oreilly.com/shoppingcart/images/happybunny.gif.

The WEB-INF directory (all ...