Apache Commons CLI库提供API，用于解析传递给程序的命令行选项。

Commons CLI可以支持不同类型的选项：

• POSIX类型选项，如tar -zxvf foo.tar.gz

• GNU类型的长选项，如du --human-readable --max-depth=1

• Java类型的属性，如java -Djava.awt.headless=true -Djava.net.useSystemProxies=true Foo

• 短选项值，如gcc -O2 foo.c

• 长选项单横线，如ant -projecthelp

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