Sample code for command line argument parsing using the Apache ES1en ES2en package

The ES2en-ES3en package of Apache is dedicated to parsing the command-line argument format.

Rely on:

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

Using this package requires:

1. Define which parameters need to be resolved, which parameters have additional options, description of each parameter, and so on, corresponding to the Options class
For example, if a command line parameter is -hfbv, we define Options to indicate which parameters really need to be parsed: if we define Option: h, f, b, then the parser will know how to match the defined Option to the command line to get each parameter when parsed. You can also define which parameters require options, such as ES20en-ES21en, and the f parameter requires the filename option. You can define a parser to parse the contents of f into the filename specified by f.

2. Parse the command line parameters according to the defined parameters that need to be resolved, corresponding to the CommandLineParser class
The String[] argus parameter passed in is parsed against the defined Options object to match each parameter, and then we can get each parameter separately.

3. Return CommandLine object, which can retrieve the information of the command line parameter.
From this object you can know which parameters are entered, which parameters are not entered, which parameters have additional options, and so on. Then we can write our own code to execute different logic according to different parameters.

Sample code:

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();
  }
  //  Define command line parameters 
  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);
  }
  //  Parse and process command line arguments 
  private void parseOptions(){
    CommandLineParser parser = new DefaultParser();
    CommandLine line = null;
    //  Resolves command-line arguments 
    try {
      line = parser.parse(opts, args);
    } catch (ParseException e) {
      System.err.println(e.getMessage());
      System.exit(1);
    }
​
    //  If the specified h Show help 
    if (args == null || args.length == 0 || line.hasOption("h")) {
      HelpFormatter help = new HelpFormatter();
      help.printHelp("encrypt", opts);
    }
​
    //  Select encrypt or decrypt operation, the default is to encrypt the file 
    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]);
  }
}

conclusion