java TrueLicense实现 实现License授权许可和验证

import com.google.common.collect.ImmutableMap;
import com.google.common.io.Files;
import com.google.common.primitives.Bytes;
import com.google.common.primitives.Ints;
import com.google.common.primitives.Longs;
import com.google.common.primitives.Shorts;
import org.truelicense.Base62;
import org.truelicense.LicenseManager;
import org.truelicense.LicenseParam;
import org.truelicense.common.Entropy;
 
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
 
public class LicenseGeneratorAndVerifier {
 
    public static void main(String[] args) throws Exception {
        // 生成公钥和私钥对
        KeyPair keyPair = generateKeyPair();
        PublicKey publicKey = keyPair.getPublic();
        PrivateKey privateKey = keyPair.getPrivate();
 
        // 生成许可证
        File licenseFile = new File("license.lic");
        generateLicense(licenseFile, publicKey, privateKey, "user", "product", new Date());
 
        // 加载许可证
        LicenseManager licenseManager = new LicenseManager(publicKey);
        licenseManager.load(licenseFile, new MyLicenseParam());
 
        // 验证许可证
        if (licenseManager.isValid()) {
            System.out.println("许可证有效");
        } else {
            System.out.println("许可证无效");
        }
    }
 
    private static KeyPair generateKeyPair() throws NoSuchAlgorithmException {
        KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
        keyGen.initialize(1024);
        return keyGen.generateKeyPair();
    }
 
    private static void generateLicense(File licenseFile, PublicKey publicKey, PrivateKey privateKey,
                                        String subject, String product, Date firstAvaliableDate) throws Exception {
        Properties props = new Properties();
        props.setProperty("subject", subject);
        props.setProperty("issuer", "MyLicensingAuthority");
        props.setPr