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Lesson 7

Java archive files - Module Conclusion

This module introduced you to Java archive files, which are used to package Beans for distribution.
You learned how to use the JAR utility to examine JAR files and package Beans in them.

JAR file format provides many benefits:

  1. Security: You can digitally sign the contents of a JAR file. Users who recognize your signature can then optionally grant your software security privileges it would not otherwise have.
  2. Decreased download time: If your applet is bundled in a JAR file, the class files of the applet and associated resources can be downloaded to a browser in a single HTTP transaction without the need for opening a new connection for each file.
  3. Compression: The JAR format allows you to compress your files for efficient storage.
  4. Packaging for extensions: The extensions framework provides a means by which you can add functionality to the Java core platform, and the JAR file format defines the packaging for extensions. By using the JAR file format, you can turn your software into extensions as well.
  5. Package Sealing: Packages stored in JAR files can be optionally sealed so that the package can enforce version consistency. Sealing a package within a JAR file means that all classes defined in that package must be found in the same JAR file.
  6. Package Versioning: A JAR file can hold data about the files it contains, such as vendor and version information.
  7. Portability: The mechanism for handling JAR files is a standard part of the Java platform's core API.




Bean Box
Bean Box

In the BeanBox toolbox, each available Bean is listed by name. The Beans that expose an icon have it shown just to the left of the name. Note that Beans are not required to expose an icon, in which case this space is left empty.
To select a Bean to be dropped onto the main form window, just click on it. The cursor will change to a crosshair, indicating that you can drop the Bean on the form by clicking on the spot where you want it placed. There is no visual indication of which Bean you have selected to drop, and there is no way to cancel out of placement mode if you decide not to drop the Bean on the form. You can, of course, remove the Bean from the form if you really did not want to put it there.

Java Archives - Quiz

Before you move on to the next module, make sure you understand the importance of how Java Archive Files are used to package JavaBeans for distribution.
Click the Quiz link below to take a multiple-choice quiz that has questions addressing the lessons worked through in this module.
Java Archives - Quiz
In the next module, the structure of Beans will be discussed.
You find out what the different parts of a Bean are, and how they come together to give JavaBeans its flexibility.