Java命令行解析：apache commons-cli

http://commons.apache.org/proper/commons-cli/usage.html

Apache Commons CLI用于解析命令行选项，也可以输出详细的选项说明信息。

Commons CLI 支持多种选项类型：

• 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)

Commons CLI处理过程可以分成三个阶段

• 定义阶段，Options类。
• 解析阶段，使用CommandLineParser类讲String[] args解析为CommandLine
• 查询阶段，调用CommandLine对象的方法，查询和提取特定选项。

命令行选型定义

Options options = new Options();
options.addOption("h", "help", false, "Print this usage information");  
options.addOption("v", "verbose", false, "Print out VERBOSE information" );  
options.addOption("p", false, "no error if existing, make parent directories as needed.");

options.addOption(OptionBuilder.withArgName("file")
                .hasArg()
                .withDescription("search for buildfile towards the root of the filesystem and use it")
                .create("O"));
options.addOption(OptionBuilder.withLongOpt("block-size")
                .withDescription("use SIZE-byte blocks")
                .withValueSeparator('=')
                .hasArg()
                .create() );

解析

CommandLineParser parser = new BasicParser( );  
CommandLineParser parser = new PosixParser(); 
CommandLine commandLine = parser.parse( options, args );  

选型查询和提取

  if( commandLine.hasOption('f') ) {  
    file = commandLine.getOptionValue('f');  
  }  

  String[] str = commandLine.getArgs();

显示帮助信息

HelpFormatter formatter = new HelpFormatter();
formatter.printHelp("xxcmd [-lkjs] PATH", "", options , "");
formatter.printHelp( "ant", options );
formatter.printHelp( "ant", options, true ); //generate a usage statment as well as the help information