解析多个 picocli（子）命令和一个 shell

Question

如何构建 Spring Boot 2.3 多命令 CLI 应用程序，它可以运行使用单个命令、@script 和交互式在 picocli？它应该像这样：

manager -u <user> -p <pass> [list|create|delete] # run and exit
manager -u <user> -p <pass> @script              # run and exit
manager -u <user> -p <pass>                      # run shell

需要用户名-u和密码-p，三个命令（list、create、delete）各有不同的选项和参数。

Answer 1

Spring 引导应用程序很简单：

@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        System.exit(SpringApplication.exit(
            SpringApplication.run(Application.class, args))
        );
    }

}

并且 Spring 使用 return 值启动 CommandLineRunner 也很简单，调用 picocli 的 CommandLine解析和执行命令：

@Component
public class ApplicationRunner implements CommandLineRunner, ExitCodeGenerator {
    private int exitCode;

    @Override
    public void run(String... args) throws Exception {
        exitCode = new CommandLine(new ConnectCommand()).execute(args);
    }

    @Override
    public int getExitCode() {
        return exitCode;
    }

}

ConnectCommand 有 showAtFileInUsageHelp = true 启用 picocli 的 @-file 支持和 mixinStandardHelpOptions 启用帮助和版本信息 "standard" 选项（-h、--help 等）：

@Command(
    name = "manager",
    description = "The manager description",
    showAtFileInUsageHelp = true,
    mixinStandardHelpOptions = true,
    subcommands = {
        ListCommand.class,
        CreateCommand.class,
        DeleteCommand.class
    })
@Component 
public class ConnectCommand implements Runnable, ExitCodeGenerator {
    @Option(
        names        = {"-u", "--username"},
        description  = "The username")
    private String username;

    @Option(
        names        = {"-p", "--password"},
        description  = "The password")
    private String password;

    private int exitCode;

    @Override
    public void run() {
        // WIP: kick-off shell
    }

    @Override
    public int getExitCode() {
        return exitCode;
    }

}

并且（子）命令都采用这种形式（根据需要散布在 picocli 的 @Option 和 @Parameters 中）：

@Command(
    name = "list",
    mixinStandardHelpOptions = true,
    header = "list stuff")
@Component
class ListCommand implements Runnable{
    @Override
    public void run() {
        System.out.println("listing...");
    }

}

有了这个，帮助现在看起来像：

Usage: manager [-hV] [-u=username] [-p=password] [@<filename>...] [COMMAND]
The manager description
      [@<filename>...]    One or more argument files containing options.
  -u, --username=name     The username
  -p, --password=pass     The password
  -h, --help              Show this help message and exit.
  -V, --version           Print version information and exit.
Commands:
  list    list stuff
  create  create stuff
  delete  delete stuff

并且运行一个命令有效：

java -jar manager.jar -u=myname -p=mypass list
listing...

并且运行包含 'list' 的@文件也可以工作：

java -jar manager.jar -u=myname -p=mypass @listing
listing...

这是 sample repository。现在我们需要折叠 shell...

解析多个 picocli（子）命令和一个 shell

Parsing multiple picocli (sub-)commands and a shell

java

picocli