'str = new String（bytes，“ UTF8”）'和'bytes = str.getBytes（“ UTF8”）'中的字节数不相同

Question

我可以看到它们与我创建字符串所用的字节不同！我已经使用“ AES / CBC / PKCS5Padding”来获取字符串。

public static void main(String[] args) {

    try {
        int randomNumber = CNStationQueueUtil.randInt(0, 99999);
        String key = "AES_KEY_TAKENUMB";
        byte[] bytes = EncryptHelper.encrypt(key, String.format("%%%d%%%d", 1001, randomNumber));
        String str = new String(bytes, "UTF8");
        System.out.println("str = " + str);
        System.out.println();
        byte[] utf8Bytes = str.getBytes("UTF8");
        printBytes(utf8Bytes, "utf8Bytes");

    } catch (Exception e) {
        e.printStackTrace();
    }

}



public class EncryptHelper {

    public static byte[] encrypt(String key, String value)
            throws GeneralSecurityException {

        byte[] raw = key.getBytes(Charset.forName("UTF-8"));
        if (raw.length != 16) {
            throw new IllegalArgumentException("Invalid key size.");
        }

        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        cipher.init(Cipher.ENCRYPT_MODE, skeySpec,
                new IvParameterSpec(new byte[16]));
        return cipher.doFinal(value.getBytes(Charset.forName("UTF-8")));
    }

    public static String decrypt(String key, byte[] encrypted)
            throws GeneralSecurityException {

        byte[] raw = key.getBytes(Charset.forName("UTF-8"));
        if (raw.length != 16) {
            throw new IllegalArgumentException("Invalid key size.");
        }
        SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");

        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        cipher.init(Cipher.DECRYPT_MODE, skeySpec,
                new IvParameterSpec(new byte[16]));
        byte[] original = cipher.doFinal(encrypted);

        return new String(original, Charset.forName("UTF-8"));
    }
}

Answer 1

当您按原样对字符串进行解码时UTF-8，是因为您将字节编码为UTF-8或兼容格式。您不能只取一个byte[]随机字节并将其转换为字符串，因为它是二进制数据而不是文本。

您可以做的是对二进制文件使用Base64编码器，并使用Base64解码器将其转换回原始字节。

这样做的一种怪癖方法是使用ISO-8859-1，但这通常是个坏主意，因为您会混淆二进制数据和文本数据。