Writing a Java Class to Manage RPM Package Content

Now our basic class structure, which is able to manipulate headers of RPM packages, is in place, and it would be a good idea to add a minimal GUI interface to it. We will build this very simple interface using the Java Swing package, available with either JDK 1.1 or JDK 1.2.

This very simple GUI interface is managed by the RpmFilePanel.Java class. This class inherits the basic JPanel graphical component and divides the screen into three parts using a Java BorderLayout:

The RpmFilePanel.java file contains a static main method to launch the Swing frame inside a Java application. You can use the JDK Java utility from the shell to start it:

java rpm.RpmFilePanel

Warning: you should have compiled the Java package and installed it in a location accessible from your CLASSPATH.

You should provide a valid RPM package file in URL form and type it into the URL field as shown below. Finally, pushing on the Load button will:

Figure 4 shows the screen layout after querying an RPM package.

Figure 4. RPM Screenshot

When you need to build the provided source package, you may use either a JDK 1.1 version or a JDK 1.2.2 version. If you use JDK1.1, the prerequisite is to download the Swing package from Sun's site.

Using Java to analyse RPM file formats may be useful, and it gives you cross-platform portability, which may help you display RPM file contents on heterogeneous platforms. This basic tool may easily be enhanced, for instance to convert RPM contents into other formats or extract other parts of an RPM package.

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