Java 工具类之 AES 加解密

import lombok.Setter;
import lombok.extern.slf4j.Slf4j;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import java.nio.charset.StandardCharsets;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

/**
 * @author potoyang
 * Description: AES 加解密工具类
 */
@Slf4j
class AESUtil {

    private static final String DEFAULT_CIPHER_ALGORITHM = "AES";

    @Setter
    private String content;

    private String secret;

    AESUtil(String content) {
        this.content = content;
        this.secret = "324iu23094u598ndsofhsiufhaf_+0wq-42q421jiosadiusadiasd";
    }

    /**
     * AES 加密
     */
    String encrypt() {
        try {
            Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);
            Key key = getKey();
            cipher.init(Cipher.ENCRYPT_MODE, key);
            byte[] result = cipher.doFinal(content.getBytes(StandardCharsets.UTF_8));
            return byte2hex(result);
        } catch (Exception e) {
            log.error("AES 加密出错: [{}]", e.getMessage());
        }
        return null;
    }

    /**
     * AES 解密
     */
    String decrypt() {
        if (content.length() < 1) {
            return null;
        }

        try {
            Cipher cipher = Cipher.getInstance(DEFAULT_CIPHER_ALGORITHM);
            Key key = getKey();
            cipher.init(Cipher.DECRYPT_MODE, key);
            byte[] original = cipher.doFinal(hex2byte(content));
            return new String(original, StandardCharsets.UTF_8);
        } catch (Exception e) {
            log.error("AES 解密出错: [{}]", e.getMessage());
        }
        return null;
    }

    private Key getKey() {
        SecretKey key = null;
        try {
            KeyGenerator generator = KeyGenerator.getInstance("AES");
            SecureRandom random = SecureRandom.getInstance("SHA1PRNG");
            random.setSeed(secret.getBytes());
            generator.init(128, random);
            key = generator.generateKey();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
        return key;
    }
    
    private byte[] hex2byte(String strhex) {
        if (strhex == null) {
            return null;
        }
        int len = strhex.length();
        if (len % 2 == 1) {
            return null;
        }
        byte[] b = new byte[len / 2];
        for (int i = 0; i != len / 2; i++) {
            b[i] = (byte) Integer.parseInt(strhex.substring(i * 2, i * 2 + 2), 16);
        }
        return b;
    }

    private static String byte2hex(byte[] b) {
        StringBuilder hs = new StringBuilder();
        String stmp;
        for (byte value : b) {
            stmp = (Integer.toHexString(value & 0XFF));
            if (stmp.length() == 1) {
                hs.append("0").append(stmp);
            } else {
                hs.append(stmp);
            }
        }
        return hs.toString().toUpperCase();
    }
}

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