用java详细实现读取jwks文件然后转换成jks文件

以下是用Java实现读取JWKS文件并将其转换成JKS文件的示例代码：

import java.io.*;
import java.net.*;
import java.security.*;
import java.security.cert.*;
import java.util.*;
import javax.net.ssl.*;
import org.json.*;

public class JWKSConverter {

    public static void main(String[] args) throws Exception {
        // 读取JWKS文件
        String jwksFile = "path/to/jwks.json";
        String jwks = readJWKSFile(jwksFile);

        // 解析JWKS文件
        List<PublicKey> publicKeys = parseJWKS(jwks);

        // 将公钥保存到JKS文件
        String jksFile = "path/to/mykeystore.jks";
        String password = "mypassword";
        savePublicKeysToJKS(publicKeys, jksFile, password);
    }

    /**
     * 读取JWKS文件
     */
    private static String readJWKSFile(String jwksFile) throws Exception {
        BufferedReader reader = new BufferedReader(new FileReader(jwksFile));
        String line;
        StringBuilder sb = new StringBuilder();
        while ((line = reader.readLine()) != null) {
            sb.append(line);
        }
        reader.close();
        return sb.toString();
    }

    /**
     * 解析JWKS文件，返回公钥列表
     */
    private static List<PublicKey> parseJWKS(String jwks) throws Exception {
        List<PublicKey> publicKeys = new ArrayList<>();
        JSONObject jwksObject = new JSONObject(jwks);
        JSONArray keysArray = jwksObject.getJSONArray("keys");
        for (int i = 0; i < keysArray.length(); i++) {
            JSONObject keyObject = keysArray.getJSONObject(i);
            String algorithm = keyObject.getString("alg");
            String modulusBase64 = keyObject.getString("n");
            String exponentBase64 = keyObject.getString("e");
            byte[] modulusBytes = Base64.getUrlDecoder().decode(modulusBase64);
            byte[] exponentBytes = Base64.getUrlDecoder().decode(exponentBase64);
            BigInteger modulus = new BigInteger(1, modulusBytes);
            BigInteger exponent = new BigInteger(1, exponentBytes);
            RSAPublicKeySpec spec = new RSAPublicKeySpec(modulus, exponent);
            KeyFactory factory = KeyFactory.getInstance("RSA");
            PublicKey publicKey = factory.generatePublic(spec);
            publicKeys.add(publicKey);
        }
        return publicKeys;
    }

    /**
     * 将公钥保存到JKS文件中
     */
    private static void savePublicKeysToJKS(List<PublicKey> publicKeys, String jksFile, String password) throws Exception {
        KeyStore keystore = KeyStore.getInstance("JKS");
        keystore.load(null, null);
        for (int i = 0; i < publicKeys.size(); i++) {
            PublicKey publicKey = publicKeys.get(i);
            String alias = "key" + i;
            keystore.setCertificateEntry(alias, getCertificate(publicKey));
        }
        FileOutputStream fos = new FileOutputStream(jksFile);
        keystore.store(fos, password.toCharArray());
        fos.close();
    }

    /**
     * 根据公钥生成证书
     */
    private static Certificate getCertificate(PublicKey publicKey) throws Exception {
        X509Certificate cert = null;
        try {
            KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
            keyPairGenerator.initialize(1024);
            KeyPair keyPair = keyPairGenerator.generateKeyPair();
            Date startDate = new Date();
            Calendar calendar = Calendar.getInstance();
            calendar.setTime(startDate);
            calendar.add(Calendar.YEAR, 1);
            Date endDate = calendar.getTime();
            X509V3CertificateGenerator certGen = new X509V3CertificateGenerator();
            certGen.setSerialNumber(BigInteger.valueOf(System.currentTimeMillis()));
            certGen.setIssuerDN(new X500Principal("CN=Issuer"));
            certGen.setNotBefore(startDate);
            certGen.setNotAfter(endDate);
            certGen.setSubjectDN(new X500Principal("CN=Subject"));
            certGen.setPublicKey(keyPair.getPublic());
            certGen.setSignatureAlgorithm("SHA256WithRSAEncryption");
            cert = certGen.generate(keyPair.getPrivate());
        } catch (Exception e) {
            e.printStackTrace();
        }
        return cert;
    }

}

上述代码中，`readJWKSFile`方法用于读取JWKS文件，`parseJWKS`方法用于解析JWKS文件并返回公钥列表，`savePublicKeysToJKS`方法用于将公钥保存到JKS文件中。其中，`getCertificate`方法根据公钥生成证书。

请注意，以上代码仅供参考，具体实现可能需要根据实际需求进行调整。