哈~AES裡面可以加自訂義字串~
版主要知道訂義字串編碼方式~
無法直接套用的~
如圖~

找到解法了 我自問自答
/*

• Click nbfs://nbhost/SystemFileSystem/Templates/Licenses/license-default.txt to change this license
• Click nbfs://nbhost/SystemFileSystem/Templates/Classes/Class.java to edit this template
  */
  import java.io.BufferedWriter;
  import java.io.FileWriter;
  import java.io.IOException;
  import java.net.URLEncoder;
  import java.nio.charset.StandardCharsets;
  import java.security.MessageDigest;
  import java.util.Arrays;
  import java.util.Base64;
  import java.util.HashMap;
  import java.util.LinkedHashMap;
  import java.util.Map;
  import javax.crypto.Cipher;
  import javax.crypto.spec.GCMParameterSpec;
  import javax.crypto.spec.SecretKeySpec;

/**
*

• @author boboboom
  */
  public class PayUni {
  public static void main(String[] args) {
  // 填入商店串接資訊
  String merID = "NPPA129180793";
  String hashKey = "12345678901234567890123456789012";// "uH9qCQ9rrv0aEgqxPBoqtcoWNLJb5Bpb";
  String hashIV = "1234567890123456";// "5lCWfCqsn81BJ3TL";

   // 建立請求參數
   Map<String, String> requestData = new HashMap<>();
   requestData.put("MerID"   , merID);
   requestData.put("Version" , "1.0");
  
   Map<String, String> data = new LinkedHashMap<>();
   data.put("MerID"      , "ABC");
   data.put("MerTradeNo" , "1658198662_93966");
   data.put("TradeAmt"   , "7017");
   data.put("Timestamp"  , "1658198662");
   data.put("ProdDesc"   , "商品說明");
   data.put("UsrMail"    , "a@presco.ws");
   data.put("ReturnURL"  , "http://lapi-epay.presco.com.tw/api/upp/return");
  
   StringBuilder sb = new StringBuilder();
   for (Map.Entry<String, String> entry : data.entrySet()) {
       sb.append(entry.getKey()).append("=").append(URLEncoder.encode(entry.getValue(), StandardCharsets.UTF_8))
               .append("&");
   }
   sb.deleteCharAt(sb.length() - 1);
  
   String encodedUrl = sb.toString();
   System.out.println("Origin:" + encodedUrl + "\r\n");
   // 產生加密字串
   String encryptInfo = encrypt(encodedUrl, hashKey, hashIV);
   System.out.println("EncryptInfo:" + encryptInfo + "\r\n");
   requestData.put("EncryptInfo", encryptInfo);
   // 產生 HashInfo
   String hashInfo = getTradeSha(encryptInfo, hashKey, hashIV);
   requestData.put("HashInfo", hashInfo);
   System.out.println("HashInfo:" + hashInfo + "\r\n");
   // 解密
   String decryptInfo = decrypt(encryptInfo, hashKey, hashIV);
   System.out.println("DecryptInfo:" + decryptInfo);
  
   getHtml(requestData);
  

  }

  public static String encrypt(String text, String key, String iv) {
  try {
  SecretKeySpec secretKeySpec = new SecretKeySpec(key.getBytes(StandardCharsets.UTF_8), "AES");
  GCMParameterSpec gcmParameterSpec = new GCMParameterSpec(128, iv.getBytes(StandardCharsets.UTF_8));

       Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
       cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, gcmParameterSpec);
       byte[] encryptedBytes = cipher.doFinal(text.getBytes(StandardCharsets.UTF_8));
  
       byte[] encryptedInfo  = Arrays.copyOfRange(encryptedBytes, 0, encryptedBytes.length-16);
       byte[] tagInfo        = Arrays.copyOfRange(encryptedBytes, encryptedBytes.length-16, encryptedBytes.length);
  
       String encodeText  = Base64.getEncoder().encodeToString(encryptedInfo);
       String encodeTag   = Base64.getEncoder().encodeToString(tagInfo);
       String finalString = encodeText + ":::" + encodeTag;
       byte[] finalBytes  = finalString.getBytes(StandardCharsets.UTF_8);
       return bytesToHex(finalBytes);
   } catch (Exception e) {
       e.printStackTrace();
   }
   return null;
  

  }

  public static String decrypt(String text, String key, String iv) {
  try {
  // Get Cipher Instance
  Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");

       // Create SecretKeySpec
       SecretKeySpec secretKeySpec = new SecretKeySpec(key.getBytes(StandardCharsets.UTF_8), "AES");
  
       // Create GCMParameterSpec
       GCMParameterSpec gcmParameterSpec = new GCMParameterSpec(128, iv.getBytes(StandardCharsets.UTF_8));
  
       // Initialize Cipher for DECRYPT_MODE
       cipher.init(Cipher.DECRYPT_MODE, secretKeySpec, gcmParameterSpec);
  
       byte[] hexToByte  = hexStringToByteArray(text);
       String encryptStr = new String(hexToByte, StandardCharsets.UTF_8);
  
       String encryptInfo = encryptStr.split(":::")[0];
       byte[] encryptInfoBytes = Base64.getDecoder().decode(encryptInfo);
  
       String tagString   = encryptStr.split(":::")[1];
       byte[] tagStringBytes = Base64.getDecoder().decode(tagString);
  
       byte[] encryptData = new byte[encryptInfoBytes.length + tagStringBytes.length];
       System.arraycopy(encryptInfoBytes, 0, encryptData, 0, encryptInfoBytes.length);
       System.arraycopy(tagStringBytes, 0, encryptData, encryptInfoBytes.length, tagStringBytes.length);
  
       byte[] decodeInfo = cipher.doFinal(encryptData);
       String decodeInfoString = new String(decodeInfo, StandardCharsets.UTF_8);
       return decodeInfoString;
   } catch (Exception e) {
       e.printStackTrace();
   }
   return null;
  

  }
  public static byte[] hexStringToByteArray(String hex) {
  int len = hex.length();
  byte[] data = new byte[len / 2];
  for (int i = 0; i < len; i += 2) {
  data[i / 2] = (byte) ((Character.digit(hex.charAt(i), 16) << 4)
  + Character.digit(hex.charAt(i + 1), 16));
  }
  return data;
  }
  private static String bytesToHex(byte[] bytes) {
  StringBuilder sb = new StringBuilder();
  for (byte b : bytes) {
  sb.append(String.format("%02x", b));
  }
  return sb.toString();
  }

  public static String getTradeSha(String data, String key, String iv) {
  String sha256 = encrySha256(key + data + iv);
  return sha256.trim();
  }

  public static String encrySha256(String value) {
  try {
  MessageDigest messageDigest = MessageDigest.getInstance("SHA-256");
  messageDigest.update(value.getBytes());
  byte byteBuffer[] = messageDigest.digest();
  StringBuffer strHexString = new StringBuffer();
  for (int i = 0; i < byteBuffer.length; i++) {
  String hex = Integer.toHexString(0xff & byteBuffer[i]);
  if (hex.length() == 1) {
  strHexString.append('0');
  }
  strHexString.append(hex);
  }
  return strHexString.toString().toUpperCase();
  } catch (Exception e) {

   }
   return null;
  

  }

  public static String getHtml(Map<String, String> data) {
  StringBuilder sb = new StringBuilder();
  sb.append("<form id="Unipay" action="https://api.payuni.com.tw/api/upp" method="post">");
  for (Map.Entry<String, String> entry : data.entrySet()) {
  String keyA = entry.getKey();
  String valueA = entry.getValue();
  sb.append("<input type="hidden"name="" + keyA + "" value="" + valueA + "">");
  }
  sb.append("<script language="JavaScript">Unipay.submit()");
  sb.append("");

   try {
       BufferedWriter writer = new BufferedWriter(new FileWriter("payment.html"));
       writer.write(sb.toString());
       writer.close();
       System.out.println("payment.html file generated successfully.");
   } catch (IOException e) {
       e.printStackTrace();
   }
  
   return sb.toString();
  

  }
  }

恩~問題解決就好唷~加油!