public class AESEncryptionDecryption {
    public static void main(String[] args) throws Exception {
        // 生成AES密鑰
        KeyGenerator keyGen = KeyGenerator.getInstance("AES");
        keyGen.init(128); // 可以是128, 192或256位
        SecretKey secretKey = keyGen.generateKey();
        byte[] keyBytes = secretKey.getEncoded();

        // 創(chuàng)建AES密鑰規(guī)范
        SecretKeySpec keySpec = new SecretKeySpec(keyBytes, "AES");

        // 獲取AES Cipher實(shí)例
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");

        // 生成隨機(jī)的IV
        byte[] ivBytes = new byte[cipher.getBlockSize()];
        IvParameterSpec ivSpec = new IvParameterSpec(ivBytes);

        // 初始化Cipher為加密模式
        cipher.init(Cipher.ENCRYPT_MODE, keySpec, ivSpec);

        // 加密數(shù)據(jù)
        String data = "這是一個(gè)需要加密的長(zhǎng)字符串...";
        byte[] encryptedBytes = cipher.doFinal(data.getBytes());

        // 將加密后的數(shù)據(jù)編碼為Base64，以便安全傳輸
        String encryptedData = Base64.getEncoder().encodeToString(encryptedBytes);

        System.out.println("加密后的字符串： " + encryptedData);

        // 初始化Cipher為解密模式
        cipher.init(Cipher.DECRYPT_MODE, keySpec, ivSpec);

        // 解密數(shù)據(jù)
        byte[] decryptedBytes = cipher.doFinal(Base64.getDecoder().decode(encryptedData));

        // 將解密后的數(shù)據(jù)轉(zhuǎn)換為字符串
        String decryptedData = new String(decryptedBytes);

        System.out.println("解密后的字符串： " + decryptedData);
    }
}

import java.security.MessageDigest;

public class HashExample {
    public static String toHexString(byte[] hash) {
        StringBuilder hexString = new StringBuilder(2 * hash.length);
        for (byte b : hash) {
            String hex = Integer.toHexString(0xff & b);
            if (hex.length() == 1) {
                hexString.append('0');
            }
            hexString.append(hex);
        }
        return hexString.toString();
    }

    public static void main(String[] args) throws Exception {
        String data = "這是一個(gè)需要加密的長(zhǎng)字符串...";

        // 獲取SHA-256 MessageDigest
        MessageDigest digest = MessageDigest.getInstance("SHA-256");
        byte[] hashBytes = digest.digest(data.getBytes());

        // 將哈希值轉(zhuǎn)換為十六進(jìn)制字符串
        String hashString = toHexString(hashBytes);

        System.out.println("哈希后的字符串: " + hashString);
    }
}