Apache Commons CLI官方文档翻译 —— 快速构建命令行启动模式

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昨天已经联系过几个基本的命令行参数使用场景，可以参考这里
通过使用Apache Commons CLI可以帮助开发者快速构建命令行启动模式，并可以快速生成帮助指令，基于用户启动参数提供不同的服务。
下面就举个例子，比如我想输入命令:
xxx -t
从而打印出当前的时间。
定义阶段——创建选项
首先要创建Options对象，然后添加Option对象.
// create Options object
Options options = new Options();
// add t option
options.addOption("t", false, "display current time");
其中addOption方法有三个参数：
第一个参数是字符串类型，代表命令的参数。
第二个参数是Bool型，代表该选项是否需要额外的参数。
第三个参数是该选项的描述信息。
上面的例子就代表，t选项不需要参数，它的意思是显示当前时间。
解析阶段——解析命令行参数
CLI通过CommandLineParser的parse方法解析命令行参数。有好几种CommandLineParser的实现类，推荐使用的是DefaultParser。看源码除了这个DefaultParser，其他的都被打上了@Deprecated标记。

除去这个DefaultParser以外，还有一个抽象类实现了CommandLineParser接口——Parser,这个Parser有三个子类：
BasicParser
GnuParser
PosixParser
CommandLineParser parser = new DefaultParser();
CommandLine cmd = parser.parse( options, args);
询问阶段—— 判断命令行中出现了哪个选项
现在就可以检查是否存在这个t选项了，首先需要在CommandLine对象中进行查询。hasOption方法可以通过选项的名字，判断命令行是否出现该命令。出现则返回true,否则返回false。
if(cmd.hasOption("t")) {
    // print the date and time
else {
    // print the date
public class DateApp {
	public static void main(String[] args) {
		String[] arg = {"-t"};
//		String[] arg = {};
		try {
			testOption(arg);
		} catch (ParseException e) {
			e.printStackTrace();
	static void testOption(String[] args) throws ParseException{
		Options options = new Options();
		options.addOption("t", false, "display current time");
		CommandLineParser parser = new DefaultParser();
		CommandLine cmd = parser.parse( options, args);
		if(cmd.hasOption("t")) {
			System.out.println((new SimpleDateFormat("yyyy-MM-dd HH:mm:ss")).format(new Date()));
		}else {
			System.out.println((new SimpleDateFormat("yyyy-MM-dd")).format(new Date()));
下面这个例子继承自DateApp，并且提供了根据城市显示时间和日期的功能。为了实现这个命令，会增加一个c选项，来添加城市信息。
// add c option
options.addOption("c", true, "country code");
第二个参数这时设置为true，就代表它需要额外的参数。
获得参数值
CommandLine对象的getOptionValue方法可以获取到参数的值。
// get c option value
String countryCode = cmd.getOptionValue("c");
if(countryCode == null) {
    // print default date
}else {
    // print date for country specified by countryCode
此时如果只有c选项，没有参数，就会报错
org.apache.commons.cli.MissingArgumentException: Missing argument for option: c
	at org.apache.commons.cli.DefaultParser.checkRequiredArgs(DefaultParser.java:211)
	at org.apache.commons.cli.DefaultParser.parse(DefaultParser.java:125)
	at org.apache.commons.cli.DefaultParser.parse(DefaultParser.java:76)
	at org.apache.commons.cli.DefaultParser.parse(DefaultParser.java:60)
	at hangout.study.InternationalDateApp.testOption(InternationalDateApp.java:29)
	at hangout.study.InternationalDateApp.main(InternationalDateApp.java:18)
public class InternationalDateApp {
	public static void main(String[] args) {
		String[] arg = {"-t","-c","hello"};
//		String[] arg = {"-t","-c"};
//		String[] arg = {};
		try {
			testOption(arg);
		} catch (ParseException e) {
			e.printStackTrace();
	static void testOption(String[] args) throws ParseException{
		Options options = new Options();
		options.addOption("t", false, "display current time");
		options.addOption("c", true, "country code");
		CommandLineParser parser = new DefaultParser();
		CommandLine cmd = parser.parse( options, args);
		if(cmd.hasOption("t")) {
			System.out.println((new SimpleDateFormat("yyyy-MM-dd HH:mm:ss")).format(new Date())+" in "+cmd.getOptionValue("c"));
		}else {
			System.out.println((new SimpleDateFormat("yyyy-MM-dd")).format(new Date()));
此时运行代码，则会正确输出信息:
2016-06-23 21:18:50 in hello
Ant样例
下面举一个Ant的样例，下面是Ant输出的帮助信息
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
使用Bool选项创建
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" );
也可以使用OptionBuilder构建选项：
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" );
最后一个OptionBuilder创建带有参数名称的选项：
Option property  = OptionBuilder.withArgName( "property=value" )
                                .hasArgs(2)
                                .withValueSeparator()
                                .withDescription( "use value for given property" )
                                .create( "D" );
通过上面的方式定义的属性，可以通过CommandLine对象的getOptionProperties("D")方法获得。
定义阶段——创建选项
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 );
解析阶段——创建解析器
跟前面类似，创建CommandLineParser解析器，返回CommandLine对象，用于查询选项参数。
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() );
询问阶段——查询命令行参数
通过hasOption选项判断是否包含某个选项参数:
// has the buildfile argument been passed?
if( line.hasOption( "buildfile" ) ) {
    // initialise the member variable
    this.buildfile = line.getOptionValue( "buildfile" );
创建帮助信息
一般命令行工具都有help帮助提示，即输入-h命令，就会输出所有的命令参数。CLI提供给我们快捷输出帮助信息的工具——HelpFormatter。
// automatically generate the help statement
HelpFormatter formatter = new HelpFormatter();
formatter.printHelp( "ant", options );
当执行到此处时，就会输出相应的帮助信息
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
public class AntExample {
	public static void main(String[] args) {
		String[] arg = {"-help"};
		testOption(arg);
	@SuppressWarnings({ "deprecation", "static-access" })
	static void testOption(String[] args){
		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" );
		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" );
		Option property  = OptionBuilder.withArgName( "property=value" )
                .hasArgs(2)
                .withValueSeparator()
                .withDescription( "use value for given property" )
                .create( "D" );
		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 );
	    CommandLineParser parser = new DefaultParser();
	    try {
	        CommandLine line = parser.parse( options, args );
		    if( line.hasOption( "buildfile" ) ) {
		       System.out.println(line.getOptionValue( "buildfile" ));
		    if( line.hasOption("help")){
			    HelpFormatter formatter = new HelpFormatter();
			    formatter.printHelp( "ant", options );
	    }catch( ParseException exp ) {
	        System.err.println( "Parsing failed.  Reason: " + exp.getMessage() );
运行后得到下面的输出信息：
usage: ant
 -buildfile <file>       use given buildfile
 -D <property=value>     use value for given property
 -debug                  print debugging information
 -emacs                  produce logging information without adornments
 -find <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
 -logfile <file>         use given file for log
 -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
如果想在输出信息中加入参数列表，也可以在printHelp加入第三个参数true， formatter.printHelp( "ant", options, true);
usage: ant [-buildfile <file>] [-D <property=value>] [-debug] [-emacs]
       [-find <file>] [-help] [-listener <classname>] [-logfile <file>]
       [-logger <classname>] [-projecthelp] [-quiet] [-verbose] [-version]
 -buildfile <file>       use given buildfile
 -D <property=value>     use value for given property
 -debug                  print debugging information
 -emacs                  produce logging information without adornments
 -find <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
 -logfile <file>         use given file for log
 -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
这个例子模拟了Linux下的命令行使用帮助：
全部代码：
public class LSExample {
	public static void main(String[] args) {
		String[] arg = new String[]{ "--block-size=10" };
		testOption(arg);
	static void testOption(String[] args){
		CommandLineParser parser = new DefaultParser();
		// 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" )
		                                .hasArg()
		                                .withArgName("SIZE")
		                                .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" );
		try {
		    CommandLine line = parser.parse( options, args );
		    if( line.hasOption( "block-size" ) ) {
		        System.out.println( line.getOptionValue( "block-size" ) );
		catch( ParseException exp ) {
		    System.out.println( "Unexpected exception:" + exp.getMessage() );
输出可以得到下面的信息:
usage: ls
 -a,--all                 do not hide entries starting with .
 -A,--almost-all          do not list implied . and ..
 -b,--escape              print octal escapes for nongraphic characters
 -B,--ignore-backups      do not list implied entried ending with ~
    --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
我的前一天总结

Apache Common CLI官方文档