code: public static void extractDirFromJar(String jarpath, String dir, String destdir) {
          ZipFile zipFile = null;
          try {
              zipFile = new ZipFile(jarpath);
              Enumeration<? extends ZipEntry> entries = zipFile.entries();
              while (entries != null && entries.hasMoreElements()) {
                  ZipEntry ze = entries.nextElement();
                  if (!ze.isDirectory() && ze.getName().startsWith(dir)) {
                      InputStream in = zipFile.getInputStream(ze);
                      try {
                          File file = new File(destdir, ze.getName());
                          if (!file.getParentFile().mkdirs()) {
                              if (!file.getParentFile().isDirectory()) {
                                  throw new IOException("Mkdirs failed to create " +
                                          file.getParentFile().toString());
                              }
                          }
                          OutputStream out = new FileOutputStream(file);
                          try {
                              byte[] buffer = new byte[8192];
                              int i;
                              while ((i = in.read(buffer)) != -1) {
                                  out.write(buffer, 0, i);
                              }
                          } finally {
                              out.close();
                          }
                      } finally {
                          if (in != null)
                              in.close();
                      }
                  }
              }
          } catch (Exception e) {
              LOG.warn("No " + dir + " from " + jarpath + "!\n" + e.getMessage());
          } finally {
              if (zipFile != null)
                  try {
                      zipFile.close();
                  } catch (Exception e) {
                      LOG.warn(e.getMessage());
                  }
  
          }
      }
docs: Extra dir from the jar to destdir
  
  @param jarpath
  @param dir
  @param destdir