如何读取Pem证书和私钥文件并创建Bouncy Castle X509Certificate和Bouncy Castle AsymmetricKeyParameter点网核心？

import org.bouncycastle.asn1.pkcs.PrivateKeyInfo;
import org.bouncycastle.cert.X509CertificateHolder;
import org.bouncycastle.openssl.PEMParser;
import org.bouncycastle.openssl.jcajce.JcaPEMKeyConverter;
import org.bouncycastle.openssl.jcajce.JcaPEMWriter;
import org.bouncycastle.util.io.pem.PemObject;
import org.bouncycastle.util.io.pem.PemReader;

public X509Certificate readCertificate(String pemFilePath) throws IOException {
    try (PemReader pemReader = new PemReader(new FileReader(pemFilePath))) {
        PemObject pemObject = pemReader.readPemObject();
        X509CertificateHolder certificateHolder = new X509CertificateHolder(pemObject.getContent());
        return new JcaX509CertificateConverter().getCertificate(certificateHolder);
    }
}

public AsymmetricKeyParameter readPrivateKey(String pemFilePath) throws IOException {
    try (PEMParser pemParser = new PEMParser(new FileReader(pemFilePath))) {
        Object pemObject = pemParser.readObject();
        if (pemObject instanceof PrivateKeyInfo) {
            return new JcaPEMKeyConverter().getPrivateKey((PrivateKeyInfo) pemObject);
        } else {
            throw new IllegalArgumentException("Invalid private key file format");
        }
    }
}

String certificateFilePath = "path/to/certificate.pem";
String privateKeyFilePath = "path/to/privatekey.pem";

X509Certificate certificate = readCertificate(certificateFilePath);
AsymmetricKeyParameter privateKey = readPrivateKey(privateKeyFilePath);