给我一个 des加密的java的类

好的，以下是一个基于DES加密的Java类的示例代码：

import javax.crypto.*;
import javax.crypto.spec.*;
import java.security.*;

public class DES {
   private static final String UNICODE_FORMAT = "UTF8";
   public static final String DES_ENCRYPTION_SCHEME = "DES";
   private KeySpec myKeySpec;
   private SecretKeyFactory mySecretKeyFactory;
   private Cipher cipher;
   byte[] keyAsBytes;
   private String myEncryptionKey;
   private String myEncryptionScheme;
   SecretKey key;

   public DES() throws Exception
   {
      myEncryptionKey = "ThisIsSecretEncryptionKey";
      myEncryptionScheme = DES_ENCRYPTION_SCHEME;
      keyAsBytes = myEncryptionKey.getBytes(UNICODE_FORMAT);
      myKeySpec = new DESKeySpec(keyAsBytes);
      mySecretKeyFactory = SecretKeyFactory.getInstance(myEncryptionScheme);
      cipher = Cipher.getInstance(myEncryptionScheme);
      key = mySecretKeyFactory.generateSecret(myKeySpec);
   }

   /**
    * Method to encrypt a plain text string using DES algorithm
    * 
    * @param unencryptedString
    * @return encryptedString
    */
   public String encrypt(String unencryptedString) {
      String encryptedString = null;
      try {
         cipher.init(Cipher.ENCRYPT_MODE, key);
         byte[] plainText = unencryptedString.getBytes(UNICODE_FORMAT);
         byte[] encryptedText = cipher.doFinal(plainText);
         encryptedString = new String(Base64.getEncoder().encode(encryptedText));
      } catch (Exception e) {
         e.printStackTrace();
      }
      return encryptedString;
   }

   /**
    * Method to decrypt an encrypted string using DES algorithm
    * 
    * @param encryptedString
    * @return decryptedString
    */
   public String decrypt(String encryptedString) {
      String decryptedText = null;
      try {
         cipher.init(Cipher.DECRYPT_MODE, key);
         byte[] encryptedText = Base64.getDecoder().decode(encryptedString.getBytes());
         byte[] plainText = cipher.doFinal(encryptedText);
         decryptedText = new String(plainText);
      } catch (Exception e) {
         e.printStackTrace();
      }
      return decryptedText;
   }

   public static void main(String args[]) {
      try {
         DES des = new DES();
         System.out.println("Encryption Key: " + des.myEncryptionKey);
         String sampleString = "This is example plain text and we will encrypt this using DES algorithm.";
         String encryptedString = des.encrypt(sampleString);
         System.out.println("Encrypted String: " + encryptedString);
         String decryptedString = des.decrypt(encryptedString);
         System.out.println("Decrypted String: " + decryptedString);
      } catch (Exception e) {
         e.printStackTrace();
      }
   }
}

注意：该示例代码中的密钥是固定的，并不是安全的方式。在实际使用时，应该使用更加安全的方式来生成和管理密钥。