<dependency>
  <groupId>commons-cli</groupId>
  <artifactId>commons-cli</artifactId>
  <version>1.3.1</version>
</dependency>

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;​
import org.apache.commons.cli.CommandLine;
import org.apache.commons.cli.CommandLineParser;
import org.apache.commons.cli.DefaultParser;
import org.apache.commons.cli.HelpFormatter;
import org.apache.commons.cli.Option;
import org.apache.commons.cli.Options;
import org.apache.commons.cli.ParseException;​
import com.lwt.util.DirUtil;​
public class CommandLineUtil {
  private String[] args;
  private Options opts = new Options();
  private File keyFile;
  private boolean encrypt;
  private boolean create;
  private boolean enName;
  private File[] files;
  private File[] dirs;
  public File getKeyFile() {
    return keyFile;
  }
  public boolean isEncrypt() {
    return encrypt;
  }
  public boolean isEnName() {
    return enName;
  }
  public boolean isCreate() {
    return create;
  }
  public File[] getFiles() {
    return files;
  }
  public File[] getDirs() {
    return dirs;
  }
​
  public CommandLineUtil(String[] args) {
    this.args = args;
    definedOptions();
    parseOptions();
    duplicate_removal();
  }
  // 定義命令行參數
  private void definedOptions(){
    Option opt_h = new Option("h", "Show this page.");
    Option opt_e = new Option("e", "encrypt", false, "Encrypt file.");
    Option opt_d = new Option("d", "decrypt", false, "Decrypt file.");
    Option opt_c = new Option("c", "create", false, "Create new key file.");
    Option opt_n = new Option("n", "name", false, "Encrypt file name.");
    Option opt_k = Option.builder("k").hasArg().argName("keyFile")
        .desc("Specify the key file").build();
    Option opt_f = Option.builder("f").hasArgs().argName("file1,file2...")
        .valueSeparator(',')
        .desc("A files list with ',' separate to handle").build();
    Option opt_r = Option
        .builder("r")
        .hasArgs()
        .argName("dir1,dir1...")
        .valueSeparator(',')
        .desc("A directories list with ',' separate to handle its child files")
        .build();
    Option opt_R = Option
        .builder("R")
        .hasArgs()
        .argName("dir1,dir1...")
        .valueSeparator(',')
        .desc("A directories list with ',' separate to recurse handle child files")
        .build();
    opts.addOption(opt_n);
    opts.addOption(opt_c);
    opts.addOption(opt_k);
    opts.addOption(opt_h);
    opts.addOption(opt_e);
    opts.addOption(opt_d);
    opts.addOption(opt_f);
    opts.addOption(opt_r);
    opts.addOption(opt_R);
  }
  // 解析處理命令行參數
  private void parseOptions(){
    CommandLineParser parser = new DefaultParser();
    CommandLine line = null;
    // 解析命令行參數
    try {
      line = parser.parse(opts, args);
    } catch (ParseException e) {
      System.err.println(e.getMessage());
      System.exit(1);
    }
​
    // 若指定h則顯示幫助
    if (args == null || args.length == 0 || line.hasOption("h")) {
      HelpFormatter help = new HelpFormatter();
      help.printHelp("encrypt", opts);
    }
​
    // 選擇加密或解密操作，默認是加密文件
    if (line.hasOption("d")) {
      if (line.hasOption("e")) {
        System.err
            .println("The -e and -d option can't specify at the same time.");
        System.exit(1);
      }
      encrypt = false;
    } else {
      encrypt = true;
      if(line.hasOption("n")){
        enName = true;
      }
    }
    if (line.hasOption("k")) {
      String k = line.getOptionValue("k");
      File file = new File(k);
      if (line.hasOption("c")) {
        keyFile = file;
        create = true;
      }else {
        if(file.isFile()){
          keyFile = file;
        } else{
          System.err.println(file + " is not a available key file");
          System.exit(1);
        }
      }
    }
​
    ArrayList<File> files = new ArrayList<File>();
    ArrayList<File> dirs = new ArrayList<File>();
    if (line.hasOption("f")) {
      String[] fs = line.getOptionValues("f");
      for(String f : fs){
        File file = new File(f);
        if(file.isFile()){
          files.add(file);
        }else{
          System.err.println(file + " is not a file");
          System.exit(1);
        }
      }
    }
​
    if (line.hasOption("r")) {
      String[] rs = line.getOptionValues("r");
      for(String r : rs){
        File dir = new File(r);
        if(dir.isDirectory()){
          dirs.add(dir);
          DirUtil dirUtil = new DirUtil(dir);
          files.addAll(Arrays.asList(dirUtil.getFiles()));
          dirs.addAll(Arrays.asList(dirUtil.getDirs()));
        }else{
          System.err.println(dir + " is not a directory");
          System.exit(1);
        }
      }
    }
​
    if (line.hasOption("R")) {
      String[] Rs = line.getOptionValues("R");
      for(String R : Rs){
        File dir = new File(R);
        if(dir.isDirectory()){
          dirs.add(dir);
          DirUtil dirUtil = new DirUtil(dir);
          files.addAll(Arrays.asList(dirUtil.getAllFiles()));
          dirs.addAll(Arrays.asList(dirUtil.getAllDirs()));
        }else{
          System.err.println(dir + " is not a directory");
          System.exit(1);
        }
      }
    }
    this.files = files.toArray(new File[0]);
    this.dirs = dirs.toArray(new File[0]);
  }
  public void duplicate_removal (){
    HashSet<File> fileSet = new HashSet<File>();
    for(File file : files){
      try {
        fileSet.add(file.getCanonicalFile());
      } catch (IOException e) {
        System.err.println(e.getMessage());
        System.exit(1);
      }
    }
    files = fileSet.toArray(new File[0]);
    fileSet = new HashSet<File>();
    for(File dir : dirs){
      try {
        fileSet.add(dir.getCanonicalFile());
      } catch (IOException e) {
        System.err.println(e.getMessage());
        System.exit(1);
      }
    }
    dirs = fileSet.toArray(new File[0]);
  }
}