Apache commons——Apache旗下的通用工具包项目

Apache Commons是Apache旗下的一个开源项目，包含了很多开源的工具，用于解决平时编程经常会遇到的问题，减少重复劳动

这里是Apache commons的官方网站

下面是工具的简单介绍：

Components
Attributes	Runtime API to metadata attributes such as doclet tags.
BCEL	Byte Code Engineering Library - analyze, create, and manipulate Java class files
BeanUtils	针对java bean的工具集，对bean进行了很多包装，可以方便地对bean进行操作，有关java bean的情况参看这里
Betwixt	用来将javabean映射为xml文件以及将xml文件映射回javabean
Chain	Chain of Responsibility pattern implemention.
CLI	用于解析命令行参数的工具
Codec	用来编码和解码，包括Base64，URL，Soundx等等
Collections	Java Collections类的拓展， collections是java.util包下的一个类，包括有关集合的操作
mpress	Defines an API for working with tar, zip and bzip2 files.
Configuration	用来帮助处理配置文件，支持多种存储方式（propertities,xml,plist,JDBC等等）
Daemon	Alternative invocation mechanism for unix-daemon-like java code.
DBCP	Database connection pooling services.
DbUtils	简化JDBC的数据库操作
Digester	xml和java对象间的映射
Discovery	Tools for locating resources by mapping service/reference names to resource names.
EL	Interpreter for the Expression Language defined by the JSP 2.0 specification.
Email	发送email的方法
Exec	API for dealing with external process execution and environment management in Java.
FileUpload	File upload capability for your servlets and web applications.
IO	IO方法的集合，可以看为java.io包的扩展
JCI	Java Compiler Interface
JCS	Java Caching System
Jelly	XML based scripting and processing engine.
Jexl	Expression language which extends the Expression Language of the JSTL.
JXPath	用XPath的方法查看javabean，有关XPath的情况看这里
Lang	Provides extra functionality for classes in java.lang.
Launcher	Cross platform Java application launcher.
Logging	Wrapper around a variety of logging API implementations.
Math	Lightweight, self-contained mathematics and statistics components.
Modeler	Mechanisms to create Model MBeans compatible with JMX specification.
Net	Collection of network utilities and protocol implementations.
Pool	Generic object pooling component.
Primitives	Smaller, faster and easier to work with types supporting Java primitive types.
Proxy	Library for creating dynamic proxies.
Sanselan	A pure-Java image library.
SCXML	An implementation of the State Chart XML specification aimed at creating and maintaining a Java SCXML engine. It is capable of executing a state machine defined using a SCXML document, and abstracts out the environment interfaces.
Transaction	Implementations for multi level locks, transactional collections and transactional file access.
Validator	Framework to define validators and validation rules in an xml file.
VFS	Virtual File System component for treating files, FTP, SMB, ZIP and such like as a single logical file system.

ps:原来在commons项目中的httpclient组件现在变为 Apache HttpComponents的一部分

参考：

http://commons.apache.org/index.html

http://www.cnblogs.com/jackyrong/archive/2006/10/15/529599.html

http://www.360doc.com/content/09/1209/16/203871_10726760.shtml