实现DES加密解密代码（自己输入密钥）

由于本人是AI语言模型，无法实际输入密钥，但可以提供DES加密解密的代码实现，供您参考：

import java.security.InvalidKeyException;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.KeyGenerator;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;

public class DES {

    public static void main(String[] args) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
        // 生成密钥
        KeyGenerator keyGenerator = KeyGenerator.getInstance("DES");
        keyGenerator.init(56);
        SecretKey secretKey = keyGenerator.generateKey();

        // 显示密钥
        byte[] key = secretKey.getEncoded();
        System.out.println("密钥：" + bytesToHexString(key));

        // 加密
        String plainText = "Hello, world!";
        byte[] cipherText = encrypt(plainText.getBytes(), secretKey);
        System.out.println("密文：" + bytesToHexString(cipherText));

        // 解密
        byte[] decryptedText = decrypt(cipherText, secretKey);
        System.out.println("明文：" + new String(decryptedText));
    }

    public static byte[] encrypt(byte[] plainText, Key key) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
        Cipher cipher = Cipher.getInstance("DES");
        cipher.init(Cipher.ENCRYPT_MODE, key);
        return cipher.doFinal(plainText);
    }

    public static byte[] decrypt(byte[] cipherText, Key key) throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException, IllegalBlockSizeException, BadPaddingException {
        Cipher cipher = Cipher.getInstance("DES");
        cipher.init(Cipher.DECRYPT_MODE, key);
        return cipher.doFinal(cipherText);
    }

    public static String bytesToHexString(byte[] bytes) {
        StringBuilder sb = new StringBuilder();
        for (byte b : bytes) {
            String hex = Integer.toHexString(b & 0xFF);
            if (hex.length() == 1) {
                sb.append("0");
            }
            sb.append(hex);
        }
        return sb.toString();
    }
}

在这个代码中，我们使用了Java内置的加密库javax.crypto来实现DES加密解密。在主函数中，我们使用KeyGenerator类来生成56位的DES密钥，然后使用encrypt()函数来加密字符串，使用decrypt()函数来解密密文。最后我们还提供了一个bytesToHexString()函数来将二进制字节数组转换成十六进制字符串以便于显示。