用Java从PEM格式的文件中提取多个X.509证书

import org.bouncycastle.openssl.PEMParser;
import org.bouncycastle.openssl.PEMException;
import org.bouncycastle.openssl.PEMKeyPair;
import org.bouncycastle.openssl.PEMParser;
import org.bouncycastle.openssl.jcajce.JcaPEMKeyConverter;
import org.bouncycastle.util.io.pem.PemObject;
import org.bouncycastle.util.io.pem.PemReader;

import java.io.FileReader;
import java.io.IOException;
import java.security.KeyPair;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.List;

public class PEMCertificateExtractor {
    public static List<X509Certificate> extractCertificates(String pemFilePath) throws IOException, CertificateException {
        List<X509Certificate> certificates = new ArrayList<>();

        try (PemReader pemReader = new PemReader(new FileReader(pemFilePath))) {
            PEMParser pemParser = new PEMParser(pemReader);

            Object pemObject;
            while ((pemObject = pemParser.readObject()) != null) {
                if (pemObject instanceof X509Certificate) {
                    certificates.add((X509Certificate) pemObject);
                }
            }
        }

        return certificates;
    }

    public static void main(String[] args) {
        String pemFilePath = "path/to/pem/file.pem";

        try {
            List<X509Certificate> certificates = extractCertificates(pemFilePath);

            for (X509Certificate certificate : certificates) {
                // 处理每个证书
                System.out.println("证书主题：" + certificate.getSubjectDN());
                System.out.println("证书颁发者：" + certificate.getIssuerDN());
                // 其他操作...
            }
        } catch (IOException | CertificateException e) {
            e.printStackTrace();
        }
    }
}