Token generation example-java

An example of generating the token code based on java is as follows:

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.util.Base64;


public class Token {

    public static String assembleToken(String version, String resourceName, String expirationTime, String signatureMethod, String accessKey)
            throws UnsupportedEncodingException, NoSuchAlgorithmException, InvalidKeyException {
        StringBuilder sb = new StringBuilder();
        String res = URLEncoder.encode(resourceName, "UTF-8");
        String sig = URLEncoder.encode(generatorSignature(version, resourceName, expirationTime
                , accessKey, signatureMethod), "UTF-8");
        sb.append("version=")
                .append(version)
                .append("&res=")
                .append(res)
                .append("&et=")
                .append(expirationTime)
                .append("&method=")
                .append(signatureMethod)
                .append("&sign=")
                .append(sig);
        return sb.toString();
    }

    public static String generatorSignature(String version, String resourceName, String expirationTime, String accessKey, String signatureMethod) 
            throws NoSuchAlgorithmException, InvalidKeyException {
        String encryptText = expirationTime + "\n" + signatureMethod + "\n" + resourceName + "\n" + version;
        String signature;
        byte[] bytes = HmacEncrypt(encryptText, accessKey, signatureMethod);
        signature = Base64.getEncoder().encodeToString(bytes);
        return signature;
    }

    public static byte[] HmacEncrypt(String data, String key, String signatureMethod)
            throws NoSuchAlgorithmException, InvalidKeyException {
        //construct a secret key from the given byte array, and the second parameter specifies a key algorithm
        SecretKeySpec signinKey = null;
        signinKey = new SecretKeySpec(Base64.getDecoder().decode(key),
                "Hmac" + signatureMethod.toUpperCase());

        //generate a Mac object for the specified Mac algorithm
        Mac mac = null;
        mac = Mac.getInstance("Hmac" + signatureMethod.toUpperCase());

        //initialize the Mac object with the given key
        mac.init(signinKey);

        //Mac operation is finished
        return mac.doFinal(data.getBytes());
    }

    public enum SignatureMethod {
        SHA1, MD5, SHA256;
    }

    public static void main(String[] args) throws UnsupportedEncodingException, NoSuchAlgorithmException, InvalidKeyException {
        String version = "2018-10-31";
        String resourceName = "products/123123";
        String expirationTime = System.currentTimeMillis() / 1000 + 100 * 24 * 60 * 60 + "";
        String signatureMethod = SignatureMethod.SHA1.name().toLowerCase();
        String accessKey = "KuF3NT/jUBJ62LNBB/A8XZA9CqS3Cu79B/ABmfA1UCw=";
        String token = assembleToken(version, resourceName, expirationTime, signatureMethod, accessKey);
        System.out.println("Authorization:" + token);
    }
}