java DES算法加密 输入：明文和密钥 输出：密文 解密 输入：密文和密钥 输出：明文

以下是Java代码实现DES算法加密和解密：

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;

public class DESUtil {
    private static final String ALGORITHM = "DES";

    /**
     * DES加密
     * @param plainText 明文
     * @param secretKey 密钥
     * @return 密文
     */
    public static String encrypt(String plainText, String secretKey) throws Exception {
        DESKeySpec desKeySpec = new DESKeySpec(secretKey.getBytes());
        SecretKeyFactory secretKeyFactory = SecretKeyFactory.getInstance(ALGORITHM);
        SecretKey key = secretKeyFactory.generateSecret(desKeySpec);

        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, key);

        byte[] result = cipher.doFinal(plainText.getBytes());
        return new String(result);
    }

    /**
     * DES解密
     * @param cipherText 密文
     * @param secretKey 密钥
     * @return 明文
     */
    public static String decrypt(String cipherText, String secretKey) throws Exception {
        DESKeySpec desKeySpec = new DESKeySpec(secretKey.getBytes());
        SecretKeyFactory secretKeyFactory = SecretKeyFactory.getInstance(ALGORITHM);
        SecretKey key = secretKeyFactory.generateSecret(desKeySpec);

        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, key);

        byte[] result = cipher.doFinal(cipherText.getBytes());
        return new String(result);
    }
}

使用示例：

public static void main(String[] args) {
    String plainText = "hello world";
    String secretKey = "12345678";

    try {
        String cipherText = DESUtil.encrypt(plainText, secretKey);
        System.out.println("Cipher text: " + cipherText);

        String decryptedText = DESUtil.decrypt(cipherText, secretKey);
        System.out.println("Decrypted text: " + decryptedText);
    } catch (Exception e) {
        e.printStackTrace();
    }
}