AESPKCS7加解密

以下方法输入格式：HEX，输出格式：HEX（注释的代码输入格式：UTF8，输出格式：UTF8）；密钥使用的是固定的string格式，并且密钥长度要满足16

import javax.crypto.Cipher;
import javax.crypto.SecretKey;

public static String encryptToHex(String data, SecretKey key) throws Exception {
		Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding"); // 使用PKCS5Padding，等同于PKCS#7Padding
		cipher.init(Cipher.ENCRYPT_MODE, key);
//		 byte[] encryptedBytes = cipher.doFinal(data.getBytes(StandardCharsets.UTF_8)); 
		byte[] encryptedBytes = cipher.doFinal(hexStringToByteArray(data));

		// 将加密后的字节转换为十六进制字符串
		StringBuilder hexString = new StringBuilder(2 * encryptedBytes.length);
		for (byte b : encryptedBytes) {
			String hex = Integer.toHexString(0xff & b);
			if (hex.length() == 1)
				hexString.append('0');
			hexString.append(hex);
		}
		return hexString.toString().toUpperCase();
	}

	public static String decryptFromHex(String hex, SecretKey key) throws Exception {
		// 将十六进制字符串转换回字节
		byte[] data = new byte[hex.length() / 2];
		for (int i = 0; i < data.length; i++) {
			int index = i * 2;
			int value = Integer.parseInt(hex.substring(index, index + 2), 16);
			data[i] = (byte) value;
		}

		Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding");
		cipher.init(Cipher.DECRYPT_MODE, key);
		byte[] decryptedBytes = cipher.doFinal(data);

//        return new String(decryptedBytes, StandardCharsets.UTF_8);  
		return ByteUtils.byteArrayToHexString(decryptedBytes);
	}

	public static byte[] hexStringToByteArray(String s) {
		int len = s.length();
		byte[] data = new byte[len / 2];
		for (int i = 0; i < len; i += 2) {
			data[i / 2] = (byte) ((Character.digit(s.charAt(i), 16) << 4) + Character.digit(s.charAt(i + 1), 16));
		}
		return data;

String keyString = "xxxxx"; 
byte[] keyBytes = keyString.substring(0, 16).getBytes(StandardCharsets.UTF_8);
SecretKey key = new SecretKeySpec(keyBytes, "AES");

}