如何用Groovy实现类似kubectl的两级CLI命令菜单？

方案1：嵌套使用CliBuilder #

虽然CliBuilder本身不直接支持多级命令，但可以通过嵌套实例化CliBuilder模拟子命令结构。核心逻辑是先解析顶级命令，再根据结果加载对应子命令的解析器。

示例代码 #

def cli = new CliBuilder(usage: 'myCli [command] [command options]')
cli.with {
    h longOpt: 'help', '显示帮助信息'
    v longOpt: 'version', '显示版本信息'
}

def options = cli.parse(args)
if (!options) return

// 处理全局选项
if (options.h) {
    cli.usage()
    println "\ncommands:"
    println "command1  Command 1 description"
    println "command2  Command 2 description"
    println "help      Help on a command"
    println "version   Show version info"
    return
}
if (options.v) {
    println "myCli v1.0.0"
    return
}

// 提取子命令与子参数
def subCommand = options.arguments()[0]
def subArgs = options.arguments()[1..-1]

// 分发处理子命令
switch(subCommand) {
    case 'command1':
        def cmd1Cli = new CliBuilder(usage: 'myCli command1 [options]')
        cmd1Cli.a '选项A的描述'
        cmd1Cli.b longOpt: 'bar', '选项B的描述'
        def cmd1Opts = cmd1Cli.parse(subArgs)
        if (!cmd1Opts) return
        println "执行command1，选项A: ${cmd1Opts.a}, 选项B: ${cmd1Opts.b}"
        break
    case 'command2':
        def cmd2Cli = new CliBuilder(usage: 'myCli command2 [options]')
        cmd2Cli.c longOpt: 'config', args:1, '配置文件路径'
        def cmd2Opts = cmd2Cli.parse(subArgs)
        if (!cmd2Opts) return
        println "执行command2，配置文件: ${cmd2Opts.c}"
        break
    case 'help':
        if (subArgs) {
            switch(subArgs[0]) {
                case 'command1':
                    new CliBuilder(usage: 'myCli command1 [options]').usage()
                    break
                case 'command2':
                    new CliBuilder(usage: 'myCli command2 [options]').usage()
                    break
                default:
                    println "未知命令: ${subArgs[0]}"
            }
        } else {
            cli.usage()
            println "\ncommands:"
            println "command1  Command 1 description"
            println "command2  Command 2 description"
            println "help      Help on a command"
            println "version   Show version info"
        }
        break
    case 'version':
        println "myCli v1.0.0"
        break
    default:
        println "未知命令: ${subCommand}"
        cli.usage()
        return
}

方案2：使用Picocli（推荐） #

如果觉得嵌套CliBuilder不够优雅，可选用Picocli——这是专门支持多级命令的Java/Groovy CLI库，语法简洁、功能完善。

示例代码 #

首先引入依赖（以Gradle为例）：

implementation 'info.picocli:picocli:4.6.3'

然后编写命令类：

import picocli.CommandLine
import picocli.CommandLine.Command
import picocli.CommandLine.Option

@Command(name = "myCli", description = "自定义Groovy CLI工具",
        subcommands = [Command1.class, Command2.class, CommandLine.HelpCommand.class, VersionCommand.class])
class MyCli {
    @Option(names = ["-h", "--help"], usageHelp = true, description = "显示帮助信息")
    boolean helpRequested

    @Option(names = ["-v", "--version"], versionHelp = true, description = "显示版本信息")
    boolean versionRequested

    static void main(String[] args) {
        int exitCode = new CommandLine(new MyCli()).execute(args)
        System.exit(exitCode)
    }
}

@Command(name = "command1", description = "Command 1 description")
class Command1 implements Runnable {
    @Option(names = ["-a"], description = "选项A的描述")
    boolean a

    @Option(names = ["-b", "--bar"], description = "选项B的描述")
    String b

    @Override
    void run() {
        println "执行command1，选项A: ${a}, 选项B: ${b}"
    }
}

@Command(name = "command2", description = "Command 2 description")
class Command2 implements Runnable {
    @Option(names = ["-c", "--config"], description = "配置文件路径", required = true)
    String configPath

    @Override
    void run() {
        println "执行command2，配置文件: ${configPath}"
    }
}

@Command(name = "version", description = "Show version info")
class VersionCommand implements Runnable {
    @Override
    void run() {
        println "myCli v1.0.0"
    }
}

Picocli的优势 #

• 原生支持多级子命令，无需手动处理参数分发
• 自动生成符合kubectl风格的规范usage信息
• 内置选项验证、类型转换、彩色输出等高级功能
• 适配Groovy简洁语法，代码可读性高

内容的提问来源于stack exchange，提问作者Lawrence Zeng