public static void main(String[] args) {

        String subjectDN = "CN=duwenlei";

        String algorithm = "";

        try {

            KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");

            keyPairGenerator.initialize(2048);

            KeyPair keyPair = keyPairGenerator.generateKeyPair();

            algorithm = keyPair.getPrivate().getAlgorithm();

            PKCS10CertificationRequestBuilder builder = new PKCS10CertificationRequestBuilder(new X500Name(subjectDN)

                    ,SubjectPublicKeyInfo.getInstance(keyPair.getPublic().getEncoded()));

            JcaContentSignerBuilder jcaBuilder = new JcaContentSignerBuilder("sha1withrsa");

//            jcaBuilder.setProvider(provider); 这里可以添加提供者

            ContentSigner contentSigner = jcaBuilder.build(keyPair.getPrivate());

            builder.build(contentSigner);

            System.out.println(builder.toString());

        } catch (NoSuchAlgorithmException e) {

            e.printStackTrace();

        } catch (OperatorCreationException e) {

            e.printStackTrace();

        }

    }