Apache-common包之common-cli笔记

  一. common-cli是命令行工具包:包括三个阶段:

1. 定义命令行选项

2. 解析命令行选项

3.解释命令行选项

二. 定义阶段:

Options类是Option类的集合

解析阶段:

CommandLineParser类为命令行解析类,解析返回CommandLine类

解释阶段:

查询CommandLine根据不同组合进行不同分支处理

三. 例子:

// create the command line parser
CommandLineParser parser = new PosixParser();

// create the Options
Options options = new Options();
options.addOption( "a", "all", false, "do not hide entries starting with ." );
options.addOption( "A", "almost-all", false, "do not list implied . and .." );
options.addOption( "b", "escape", false, "print octal escapes for nongraphic "
                                         + "characters" );
options.addOption( OptionBuilder.withLongOpt( "block-size" )
                                .withDescription( "use SIZE-byte blocks" )
                                .withValueSeparator( '=' )
                                .hasArg()
                                .create() );
options.addOption( "B", "ignore-backups", false, "do not list implied entried "
                                                 + "ending with ~");
options.addOption( "c", false, "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" );
options.addOption( "C", false, "list entries by columns" );

String[] args = new String[]{ "--block-size=10" };

try {
    // parse the command line arguments
    CommandLine line = parser.parse( options, args );

    // validate that block-size has been set
    if( line.hasOption( "block-size" ) ) {
        // print the value of block-size
        System.out.println( line.getOptionValue( "block-size" ) );
    }
}
catch( ParseException exp ) {
    System.out.println( "Unexpected exception:" + exp.getMessage() );
}

四. 自动生成帮助声明:

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

打印出来信息:

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