Java通过字符串加密/解密因填充而不起作用

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;
import java.util.Base64;

public class EncryptionExample {
    private static final String ALGORITHM = "AES";
    private static final String KEY = "mySecretKey12345";

    public static String encrypt(String plaintext) throws Exception {
        SecretKeySpec secretKey = new SecretKeySpec(KEY.getBytes(StandardCharsets.UTF_8), ALGORITHM);
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, secretKey);
        byte[] encryptedBytes = cipher.doFinal(plaintext.getBytes(StandardCharsets.UTF_8));
        return Base64.getEncoder().encodeToString(encryptedBytes);
    }

    public static String decrypt(String ciphertext) throws Exception {
        SecretKeySpec secretKey = new SecretKeySpec(KEY.getBytes(StandardCharsets.UTF_8), ALGORITHM);
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, secretKey);
        byte[] decryptedBytes = cipher.doFinal(Base64.getDecoder().decode(ciphertext));
        return new String(decryptedBytes, StandardCharsets.UTF_8);
    }

    public static void main(String[] args) throws Exception {
        String plaintext = "Hello, World!";
        String ciphertext = encrypt(plaintext);
        System.out.println("Encrypted: " + ciphertext);
        String decryptedText = decrypt(ciphertext);
        System.out.println("Decrypted: " + decryptedText);
    }
}