Commons CLI 学习（1）

The Apache Commons CLI library provides an API for parsing command line options passed to programs. It's also able to print help messages detailing the options available for a command line tool.

Apache Commons CLI库提供了一批API，用来解析以命令行形式传递给程序的参数。同事，也可以用来打印 如何使用这些参数的help信息。

Apache Commons CLI支持的类型有：

• POSIX like options (ie. tar -zxvf foo.tar.gz)
• GNU like long options (ie. du --human-readable --max-depth=1)
• Java like properties (ie. java -Djava.awt.headless=true -Djava.net.useSystemProxies=true Foo)
• Short options with value attached (ie. gcc -O2 foo.c)
• long options with single hyphen (ie. ant -projecthelp)

一个典型的Apache Commons CLI使用方式如下：

usage: ls
 -A,--almost-all          do not list implied . and ..
 -a,--all                 do not hide entries starting with .
 -B,--ignore-backups      do not list implied entried ending with ~
 -b,--escape              print octal escapes for nongraphic characters
    --block-size <SIZE>   use SIZE-byte blocks
 -c                       with -lt: sort by, and show, ctime (time of last
                          modification of file status information) with
                          -l:show ctime and sort by name otherwise: sort
                          by ctime
 -C                       list entries by columns