Saturday, March 20, 2010

Progress: TreeProperties

I just realized that I didn't post anything for about two months. Well, I did do something, and I want to keep you up.

I have to say that code versioning systems like SVN are a great thing. Besides having a backup on the internet, I'm able to trace back my actions in the last two months. You can look here anytime to see what I was coding recently.

My task was to rework the TreeProperties system that i have come up with sometimes. The point behind it is that you can store properties in simple text files and, for example, implement localization this way. Well, java has something like that built in, but my Library allows much more, the biggest pro being that properties can be split over several files and keys are hierarchical. You can read more about - and download - it here.


Then was a long pause, I took a vacation and went skiing. After that, work went on, and I added many features, fixed bugs etc. In a nutshell, what the library is able to do is:
  • Store properties in a tree structure of multiple files
    A file can reference another file, which is then parsed in the same way. Thus, any structure of files may be used to realize the needed properties.
  • Use hierarchical property-keys, like "/lang/en/save"
    The namespace mechanism is independent of the file structure, i.e. not bound to a directory structure. When a file is referenced, it inherits its referrer's namespace. For example, if you reference a file with the key "/lang/en", its "save" property has the full key "/lang/en/save". However, if you prefer, you can reference the file with the empty key and literally use "/lang/en/save" in the included file for the same result.
  • Support for many data types
    Unlike the java Properties class, which only supports unparsed string values, TreeProperties supports many data types out of the box - no more casting and parsing when accessing properties! Data types include all of the java primitive types, String, BigInteger and BigDecimal, Date and Calendar, File, Path and URL. The mechanism of data types is easily extendable. It requires implementing one interface and registering the type - that's it!
    Special attention goes to the Path type - it adds an abstraction to regular java files that allows to use system properties to be substituted in the path. for example, the values "~/file.txt" or "${user.home}/file.txt", interpreted using the path type, both represent the file "file.txt" in the executing user's home directory. Including files (see above) uses the path type to parse the include, therefore the included file may be personalized for each user, allowing him to set preferences without annoying other users.
  • Simple access to the API
    Most needs don't go beyond reading and writing existing properties. Therefore there's a class for exactly that - it has convenience methods that return the standard types already cast, allows default values, and supports localization. The only reason to read into the API is if you need to store new properties.
  • Easy GUI
    TreeProperties is a background utility that makes a developer's life way easier. However, now and then there's a case when it steps into the foreground. If you want to show a GUI to the user to let him edit the values, don't build it yourself. It's already there! Setting up a GUI with labels and input components to allow the user to edit properties requires a single method call. what you get is a fully layouted swing panel, ready to add to your GUI. The input components are adjusted for the data type - (formatted) text fields, checkboxes and dropdown fields - and initialized to the current value. Changes to the inputs write to the properties object and are therefore available immediately.
I hope you enjoyed the insight and my work - TreeProperties is open source and can be downloaded as a single jar file. More infos about file formats and usage here.

Next time is about the new sibling of the LaternaMagica project, LaternaCommon, which adds even another level of convenience for the developer in the areas of logging, error handling and deployment.

1 comment:

Silly Freak said...

I have the feeling that comments regularly disappear from this page; I get the mail-notification, but never see any comments. anyway:

"Hi there,
I have a message for the webmaster/admin here at laterna--magica.blogspot.com.
Can I use some of the information from this post above if I give a backlink back to this website?
Thanks,
Jack"

feel free to use the contents of my posts, or my project at google code for noncommercial purposes; its licensed under the GPLv3. I'd be glad for you linking to me, but that's entirely your choice