Java CLI 解析器

Question

我知道这个问题已经被问过了，但我正在寻找具有特定功能的 Java cli 解析器。我希望它能够定义命令行树，从而使用子命令(以及不止一个级别的深度)。因此，在我进入选项之前，我可以有 3-4 级命令。而且这些子命令是互斥的。谢谢

Answer 1

可以用JCommander来完成.每个 JCommander 对象本质上都是一个具有任意数量参数和/或任意数量嵌套子命令的命令，其中顶级 JCommander 对象是 root 命令。命令参数始终特定于为其声明的命令，并且不干扰其他命令的参数。添加子命令的界面不是很直观，但是是可能的(参见 addCommand 方法())

这是一个概念验证测试类:

public class Test{

@Test
public void nestedSubCommandTest() {
    GeneralOptions generalOpts = new GeneralOptions();
    JCommander jc = new JCommander(generalOpts);

    Command command = new Command();
    JCommander jc_command = addCommand(jc, "command", command);

    SubCommand1 subcommand1 = new SubCommand1();
    JCommander jc_subcommand1 = addCommand(jc_command, "subcommand1",
            subcommand1);

    SubCommand2 subcommand2 = new SubCommand2();
    JCommander jc_subcommand2 = addCommand(jc_subcommand1, "subcommand2",
            subcommand2);

    SubCommand3 subcommand3 = new SubCommand3();
    addCommand(jc_subcommand2, "subcommand3", subcommand3);

    jc.parse("--general-opt", 
        "command", "--opt", 
        "subcommand1",
        "subcommand2", "--sub-opt2", 
        "subcommand3", "--sub-opt3");

    assertTrue(generalOpts.opt);// --general-opt was set
    assertTrue(command.opt);// command --opt was set
    assertFalse(subcommand1.opt);// subcommand1 --sub-opt1 was not set
    assertTrue(subcommand2.opt);// subcommand2 --sub-opt2 was set
    assertTrue(subcommand3.opt);// subcommand3 --sub-opt3 was set
}

private static JCommander addCommand(JCommander parentCommand,
        String commandName, Object commandObject) {
    parentCommand.addCommand(commandName, commandObject);
    return parentCommand.getCommands().get(commandName);
}

public static class GeneralOptions {
    @Parameter(names = "--general-opt")
    public boolean opt;
}

@Parameters
public static class Command {
    @Parameter(names = "--opt")
    public boolean opt;
}

@Parameters
public static class SubCommand1 {
    @Parameter(names = "--sub-opt1")
    public boolean opt;
}

@Parameters
public static class SubCommand2 {
    @Parameter(names = "--sub-opt2")
    public boolean opt;
}

@Parameters
public static class SubCommand3 {
    @Parameter(names = "--sub-opt3")
    public boolean opt;
}
}

编辑:如何重用命令。

方案一，使用继承:

  public class CommonArgs{
    @Parameter(names="--common-opt")
    public boolean isCommonOpt;
  }

  @Parameters(description = "my command 1")
  public class MyCommand1 extends CommonArgs{}

  @Parameters(description = "my command 2")
  public class MyCommand2 extends CommonArgs{}

我认为这个的用法和行为是显而易见的。一个缺点是您只能从一个类扩展，该类将来可能会限制可重用性。

解决方案 2，使用组合模式(参见 doc here):

  public class CommonArgs{
    @Parameter(names="--common-opt")
    public boolean isCommonOpt;
  }

  @Parameters(description = "my command 1")
  public class MyCommand1{
    @ParametersDelegate
    public CommonArgs commonArgs = new CommonArgs();
  }

  @Parameters(description = "my command 2")
  public class MyCommand2{
    @ParametersDelegate
    public CommonArgs commonArgs = new CommonArgs();
  }

在这里，嵌套的commonArgs 类的参数将被视为命令类的直接参数。您可以根据需要添加任意数量的委托(delegate)，甚至可以将委托(delegate)嵌套在其他委托(delegate)中等等。要在解析后获取委托(delegate)选项的值，只需执行 myCommand1.commonArgs.isCommonOpt 等