Running Java Class from Terminal

How to run Java class in Terminal

This is to create and run one or more java files on terminal that is depends on third-party jars.

This helps to quickly test some features on real environment without running E2E flow of your application.

• Write java file that you want to run

FileCleanupUtil.java

package codergists;

import org.apache.commons.io.filefilter.AgeFileFilter;

import java.io.File;
import java.io.IOException;
import java.util.Collection;
import java.util.Date;
import java.util.stream.Stream;

import static java.time.LocalDate.now;
import static java.time.ZoneId.systemDefault;
import static java.util.Date.from;
import static org.apache.commons.io.FileUtils.deleteDirectory;
import static org.apache.commons.io.FileUtils.listFilesAndDirs;

/**
 * Utility class cleanup archived session files which are older than 2 weeks
 *
 * @author tvajjala
 */
public class FileCleanupUtil {

  /**
   * Threshold time
   */
  private static final int THRESHOLD = 2;//weeks
  /**
   * cutOff date
   */
  private static final Date cutoffDate = from(now().minusWeeks(THRESHOLD).atStartOfDay(systemDefault()).toInstant());

  /**
   * ThreadShould date filter
   */
  private static AgeFileFilter ageFileFilter = new AgeFileFilter(cutoffDate);

  /**
   * Directories to search for older files
   */
  private static String[] DEFAULT_DIRS = new String[]{"/dir1/", "/dir2/dir3/"};

  /**
   * Scan Directory
   *
   * @param parentDir
   */
  static void scanDirectory(File parentDir) {

    System.out.println("Searching old files under" + parentDir + "with cutoff date" + cutoffDate);

    Collection<File> list = listFilesAndDirs(parentDir, ageFileFilter, ageFileFilter);

    list.stream().filter(f -> !f.isDirectory())
        .forEach(f -> System.out.println(f + " deleted ?" + f.delete()));

    list.stream().filter(dir -> dir.isDirectory() && !dir.equals(parentDir))
        .forEach(dir -> {
          System.out.println("Deleting dir " + dir);
          scanDirectory(dir);
          try {
            if (dir.list().length != 0) {
              System.out.println(dir + " directory not empty");
              return;
            }
            deleteDirectory(dir);
          } catch (IOException ioException) {
            System.out.println("Failed to delete directory" + dir);
          }
        });
  }

  static void cleanupOldFiles(String... parentDirs) {
    Stream.of(parentDirs)
          .map(dir -> new File(dir))
          .forEach(parentDir -> scanDirectory(parentDir));
  }

  /**
   * Public API Specify default parent directories
   */
  public static void deleteOldFiles() {
    cleanupOldFiles(DEFAULT_DIRS);
  }

  /**
   * Specify command line arguments (standalone mode)
   *
   * @param args list of directories
   */
  public static void main(String[] args) {
    cleanupOldFiles(args);
  }

}

• Compile java file

Compile java file and place it under right directory NOTE: -d . option directory we specified using package

compile.sh

javac -cp lib/a.jar:lib/b.jar:lib/c.jar -d . FileCleanupUtil.java

javac -cp lib/commons-io-2.8.0.jar:lib/slf4j-api-1.7.25.jar -d . FileCleanupUtil.java

• Create temporary jar with your classes

jar.sh

jar -cvf file-filter.jar codergists/*

# To verify content inside jar
jar -tf file-filter.jar

• Run program

run.sh

java -cp file-filter.jar:lib/* codergists.FileCleanupUtil /path/to/parent/dir /path/2nd/dir

• To supply log configuration

logConfig.sh

java -Dlog4j.configurationFile=log4j2.xml -cp file-filter.jar:lib/* codergists.FileCleanupUtil /path/to/parent/dir /path/2nd/dir