Java™ Application Development on Linux - Dator

5.11 Bundling a Java Program: Put It in a JAR161JAR file and run java against it. With this simple setup, users need not evenknow they are using a Java application—it runs like any other application.5.11.1.1 The Manifest FileThe only way in which jar really differs from any other ZIP archive utility isin the automatic creation and use of a manifest file, by default namedMETA-INF/MANIFEST in the archive. Even if you do not specify a manifest fileof your own, the jar utility creates one for you. Let’s take a moment to look atwhat goes into the manifest.A manifest is basically a list of key/value pairs. The key comes at the startof a line and the value comes at the end of the line with a colon separating thetwo. Example 5.21 shows a sample manifest.Example 5.21 Manifest from the Payback sample applicationManifest-Version: 1.0Ant-Version: Apache Ant 1.5.3Created-By: 1.4.1_02-b06 (Sun Microsystems Inc.)Version: 1.0Main-Class: net.multitool.Payback.PaybackAll of these entries were produced automatically by ant or the jar utilityitself, except for Main-Class, which we specified (albeit with ant, as you willsee in Chapter 9). The manifest has certain values that are always filled in byjar, but two that you might commonly specify are• Main-Class, which allows users to run a Java application by merely typingjava someJarFile.jar, without having to know the fully packagequalified name of the class that contains the application’s main().• Class-Path, which allows you to specify what the classpath should bewhen the application is run.There are keys specific to applets, to signed applications, to beans, and soforth. We will address these as it becomes necessary. Full details can, of course,be found in the Sun’s documentation for jar. 2727. http://java.sun.com/j2se/1.4.2/docs/tooldocs/solaris/jar.html