apach-commons 工具包学习

Commons是apach下属的开源子项目，专门提供一些通用的工具类。 这些方法用起来后，程序看起来更加简单，专业。 Commons的主要类结构： Attributes Runtime API to metadata attributes such as doclet tags. BeanUtils Easy-to-use wrappers around the Java reflection and introspection APIs. Betwixt Services for mapping JavaBeans to XML documents, and vice versa. Chain Chain of Responsibility pattern implemention. CLI Command Line arguments parser. Codec General encoding/decoding algorithms (for example phonetic, base64, URL). Collections Extends or augments the Java Collections Framework. Compress Defines an API for working with tar, zip and bzip2 files. Configuration Reading of configuration/preferences files in various formats. Daemon Alternative invocation mechanism for unix-daemon-like java code. DBCP Database connection pooling services. DbUtils JDBC helper library. Digester XML-to-Java-object mapping utility. 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 Library for sending e-mail from Java. Exec API for dealing with external process execution and environment management in Java. FileUpload File upload capability for your servlets and web applications. IO Collection of I/O utilities. JCI Java Compiler Interface Jelly XML based scripting and processing engine. Jexl Expression language which extends the Expression Language of the JSTL. JXPath Utilities for manipulating Java Beans using the XPath syntax. 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.

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