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.