picocliを利用したサンプルプログラム

FileTool.java

import picocli.CommandLine;
import picocli.CommandLine.Command;
import picocli.CommandLine.HelpCommand;
import picocli.CommandLine.Model.CommandSpec;
import picocli.CommandLine.Option;
import picocli.CommandLine.Parameters;
import picocli.CommandLine.ScopeType;
import picocli.CommandLine.Spec;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Arrays;
import java.util.List;
import java.util.function.Consumer;
import java.util.stream.Stream;

@Command(name = "file-tool", version = "file-tool 0.1", mixinStandardHelpOptions = true,
        description = "File tool", subcommands = HelpCommand.class, scope = ScopeType.INHERIT)
public class FileTool implements Runnable {

    @Spec
    CommandSpec commandSpec;

    @Option(names = {"--header"}, negatable = true,
            description = "Show header.",
            scope = ScopeType.INHERIT)
    boolean header;

    @Option(names = {"-d", "--delimiter"}, defaultValue = "\t",
            description = "Set delimiter (default: \\t).", paramLabel = "DELIMITER",
            scope = ScopeType.INHERIT)
    private String delimiter;

    public static void main(String... args) {
        int exitCode = new CommandLine(new FileTool()).execute(args);
        System.exit(exitCode);
    }

    @Override
    public void run() {
        commandSpec.commandLine().printVersionHelp(System.out);
    }

    @Command(name = "size", description = "Print file size.")
    void size(@Parameters(paramLabel = "PATH",
            description = {"File path(s).",
                    "The default is the current directory (${DEFAULT-VALUE})."},
            defaultValue = "${sys:user.dir}") List<Path> paths) {
        showHeader("size");
        paths.forEach(path -> walk(path.normalize().toAbsolutePath(), this::printSize));
    }

    void printSize(final Path path) {
        try {
            print(String.valueOf(path), Long.toString(Files.size(path)));
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    @Command(name = "type", description = "Print file content type.")
    void contentType(@Parameters(paramLabel = "PATH",
            description = {"File path(s).",
                    "The default is the current directory (${DEFAULT-VALUE})."},
            defaultValue = "${sys:user.dir}") List<Path> paths) {
        showHeader("type");
        paths.forEach(path -> walk(path.normalize().toAbsolutePath(), this::printContentType));
    }

    void printContentType(final Path path) {
        try {
            print(String.valueOf(path), Files.probeContentType(path));
            System.out.printf("%s%s%s%n", path, delimiter, Files.probeContentType(path));
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    private void showHeader(final String... headers) {
        if (header) {
            print(Stream.concat(Stream.of("path"), Arrays.stream(headers)).toArray(String[]::new));
        }
    }

    private void print(final String... values) {
        System.out.printf("%s%n", String.join(delimiter, values));
    }

    private void walk(final Path path, final Consumer<Path> consumer) {
        if (Files.isDirectory(path)) {
            try (Stream<Path> children = Files.list(path)) {
                children.forEachOrdered(p -> walk(p, consumer));
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        } else {
            consumer.accept(path);
        }
    }
}