十一周作业

public class Sha256Utils {
    private static Mac sha256_HMAC;
    static {
        try {
            sha256_HMAC = Mac.getInstance("HmacSHA256");
        } catch (NoSuchAlgorithmException e) {
            System.err.println("Init Error");
        }
    }
    public static String hmacSha256(String key, String message) {
        try {
            SecretKeySpec secret_key = new SecretKeySpec(key.getBytes(), "HmacSHA256");
            sha256_HMAC.init(secret_key);
            String hash = Base64.getEncoder().encodeToString(sha256_HMAC.doFinal(message.getBytes()));
            return hash;
        } catch (Exception e){
            System.err.println("Encrypt Password Error");
        }
        return "";
    }
}
public class User {
    private Map<String, String> userMap = new ConcurrentHashMap<>();
    public boolean checkPW(String userName, String password) {
        String encryptPassword = Sha256Utils.hmacSha256(userName, password);
        String userPassword = userMap.get(userName);
        if (encryptPassword.equals(userPassword)) {
            return true;
        } else {
            return false;
        }
    }
    public void register(String userName, String password) {
        String encryptPassword = Sha256Utils.hmacSha256(userName, password);
        if ("".equals(encryptPassword)) {
            throw new RuntimeException("User Register Fail");
        }
        userMap.put(userName, encryptPassword);
    }
    public static void main(String[] args) {
        User user = new User();
        user.register("chenwei", "chenwei123");
        System.out.println(user.checkPW("chenwei", "chenwei"));
        System.out.println(user.checkPW("chenwei", "chenwei123"));
    }
}