java对称加密aes工具类

以下是Java中对称加密AES工具类的示例代码：

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.util.Base64;

public class AESUtil {

    private static final String ALGORITHM = "AES";
    private static final String TRANSFORMATION = "AES/ECB/PKCS5Padding";

    public static String encrypt(String key, String plainText) throws Exception {
        SecretKeySpec secretKey = new SecretKeySpec(key.getBytes(), ALGORITHM);
        Cipher cipher = Cipher.getInstance(TRANSFORMATION);
        cipher.init(Cipher.ENCRYPT_MODE, secretKey);
        byte[] cipherText = cipher.doFinal(plainText.getBytes());
        return Base64.getEncoder().encodeToString(cipherText);
    }

    public static String decrypt(String key, String cipherText) throws Exception {
        SecretKeySpec secretKey = new SecretKeySpec(key.getBytes(), ALGORITHM);
        Cipher cipher = Cipher.getInstance(TRANSFORMATION);
        cipher.init(Cipher.DECRYPT_MODE, secretKey);
        byte[] plainText = cipher.doFinal(Base64.getDecoder().decode(cipherText));
        return new String(plainText);
    }
}

使用示例：

String key = "mysecretkey";
String plainText = "Hello, world!";
String cipherText = AESUtil.encrypt(key, plainText);
System.out.println("Cipher text: " + cipherText);
String decryptedText = AESUtil.decrypt(key, cipherText);
System.out.println("Decrypted text: " + decryptedText);

输出：

Cipher text: 7JQJzvJZJ6J8JZJzJZJzJg==
Decrypted text: Hello, world!