You may have some recurring development tasks while your daily work with java in different projects. For example you again and again write some small code that capitalizes a given String. Or you write an application with a command line interface and write code that defines and parses your command line options. Or you need some little helpers for your database handling. Or …
These are only some examples and if you don’t have already written and built your own little libraries for those tasks, you may want to have a look at Apache Commons, formerly known as Jakarta Commons. There are libraries for everyday use in different packages.
I will provide you a short overview over Apache Commons here and write some more articles about some of their libraries in the next weeks.
So, Apache Commons assign their libraries to three repositories depending on their development stage and usage (list taken from their site):
- The Commons Proper – A repository of reusable Java components.
- The Commons Sandbox – A workspace for Java component development.
- The Commons Dormant – A repository of Sandbox components that are currently inactive.
I will focus on Commons Proper in this and my following articles since the contained components are ready to use and stable.
Currently, Commons Proper contains 39 components. You can categorize them into web, xml, utilities, converters and Java API extension.
The following table is taken and translated from german Wikipedia:
| Category | Components |
|---|---|
| Web | FileUpload, Net, EL, Email, Jexl |
| XML | Betwixt, Digester, Jelly, JXPath |
| Utilities | BeanUtils, Pool, Validator, Daemon, Discovery, Exec, Launcher, JCI, Jelly, Modeler, SCXML, Chain |
| Converters | Codec, Compress |
| Java API Extensions | Lang, Collections, IO, Logging, Configuration, DBCP, DbUtils, Math, Primitives, Proxy, Validator, VFS, Attributes, CLI, Discovery, Transaction |