以Ant为例，首先Ant的命令格式如下所示

ant [options] [target [target2 [target3] ...]]
  Options: 
  -help                  print this message
  -projecthelp           print project help information
  -version               print the version information and exit
  -quiet                 be extra quiet
  -verbose               be extra verbose
  -debug                 print debugging information
  -emacs                 produce logging information without adornments
  -logfile <file>        use given file for log
  -logger <classname>    the class which is to perform logging
  -listener <classname>  add an instance of class as a project listener
  -buildfile <file>      use given buildfile
  -D<property>=<value>   use value for given property
  -find <file>           search for buildfile towards the root of the
                         filesystem and use it

Boolean选项

创建使用的boolean选项

Option help = new Option( "help", "print this message" );
Option projecthelp = new Option( "projecthelp", "print project help information" );
Option version = new Option( "version", "print the version information and exit" );
Option quiet = new Option( "quiet", "be extra quiet" );
Option verbose = new Option( "verbose", "be extra verbose" );
Option debug = new Option( "debug", "print debugging information" );
Option emacs = new Option( "emacs",
                           "produce logging information without adornments" );

参数选项

参数选项通过OptionBuilder创建

Option logfile   = OptionBuilder.withArgName( "file" )
                                .hasArg()
                                .withDescription(  "use given file for log" )
                                .create( "logfile" );

Option logger    = OptionBuilder.withArgName( "classname" )
                                .hasArg()
                                .withDescription( "the class which it to perform "
                                                  + "logging" )
                                .create( "logger" );

Option listener  = OptionBuilder.withArgName( "classname" )
                                .hasArg()
                                .withDescription( "add an instance of class as "
                                                  + "a project listener" )
                                .create( "listener"); 

Option buildfile = OptionBuilder.withArgName( "file" )
                                .hasArg()
                                .withDescription(  "use given buildfile" )
                                .create( "buildfile");

Option find      = OptionBuilder.withArgName( "file" )
                                .hasArg()
                                .withDescription( "search for buildfile towards the "
                                                  + "root of the filesystem and use it" )
                                .create( "find" );

Java属性选项

Java属性选项也可以使用OptionBuilder创建

Option property  = OptionBuilder.withArgName( "property=value" )
                                .hasArgs(2)
                                .withValueSeparator()
                                .withDescription( "use value for given property" )
                                .create( "D" );

创建Options

Options options = new Options();

options.addOption( help );
options.addOption( projecthelp );
options.addOption( version );
options.addOption( quiet );
options.addOption( verbose );
options.addOption( debug );
options.addOption( emacs );
options.addOption( logfile );
options.addOption( logger );
options.addOption( listener );
options.addOption( buildfile );
options.addOption( find );
options.addOption( property );

创建Parser

创建CommandLineParser

public static void main( String[] args ) {
    // create the parser
    CommandLineParser parser = new DefaultParser();
    try {
        // parse the command line arguments
        CommandLine line = parser.parse( options, args );
    }
    catch( ParseException exp ) {
        // oops, something went wrong
        System.err.println( "Parsing failed.  Reason: " + exp.getMessage() );
    }
}

查询commandline

// has the buildfile argument been passed?
if( line.hasOption( "buildfile" ) ) {
    // initialise the member variable
    this.buildfile = line.getOptionValue( "buildfile" );
}

用法/帮助

HelpFormatter类可以自动生成用法和帮助信息

// automatically generate the help statement
HelpFormatter formatter = new HelpFormatter();
formatter.printHelp( "ant", options );

执行结果如下所示

usage: ant
-D <property=value>     use value for given property
-buildfile <file>       use given buildfile
-debug                  print debugging information
-emacs                  produce logging information without adornments
-file <file>            search for buildfile towards the root of the
                        filesystem and use it
-help                   print this message
-listener <classname>   add an instance of class as a project listener
-logger <classname>     the class which it to perform logging
-projecthelp            print project help information
-quiet                  be extra quiet
-verbose                be extra verbose
-version                print the version information and exit