Codec ： 编码、解码

编码：将字符以某种格式转化为二进制数据
解码：将二进制数据以某种格式解析为其对应的字符

Apache Codec


Packages
Package    Description
1. org.apache.commons.codec    
Interfaces and classes used by the various implementations in the sub-packages.
子包中的实现类所使用的接口和类

2.org.apache.commons.codec.binary    
Base64, Base32, Binary, and Hexadecimal String encoding and decoding.
Base64，Base32，二进制，和十六进制字符串的编码的编码和解码

3.org.apache.commons.codec.cli    
Command line utility.
命令行工具

4.org.apache.commons.codec.digest    
Simplifies common MessageDigest tasks and includes a libc crypt(3) compatible crypt method that supports DES, MD5, SHA-256 and SHA-512 based algorithms as well as the Apache specific "$apr1$" variant.
简化了信息摘要的工作，MD5（ Message-Digest Algorithm），SHA（Secure Hash Algorithm） 都是单向加密算法，适合做信息摘要， DES （Data Encryption Standard）是对称加密算法，加密和解密所用的密钥相同
//此外，还有一种非对称加密算法 RSA，codec并未提供，jdk带的有一个


org.apache.commons.codec.language    
Language and phonetic encoders.
org.apache.commons.codec.language.bm    
Implementation details of the Beider-Morse codec.
org.apache.commons.codec.net    
Network related encoding and decoding.