public static String genCSR(String subject, String alg,String provider)            throws InvalidKeyException, NoSuchAlgorithmException,            NoSuchProviderException, SignatureException, OperatorCreationException {        String signalg="";        int alglength=0;        String keyAlg="";        if(alg.toUpperCase().equals("RSA1024")){            signalg="SHA1WithRSA";            alglength=1024;            keyAlg="RSA";        }else if(alg.toUpperCase().equals("RSA2048")){            signalg="SHA1WithRSA";            alglength=2048;            keyAlg="RSA";        }else if(alg.toUpperCase().equals("SM2")){            signalg="SM3withSM2";            alglength=256;            keyAlg="SM2";        }        KeyPairGenerator keyGen = KeyPairGenerator.getInstance(keyAlg);        keyGen.initialize(alglength);        KeyPair kp = keyGen.generateKeyPair();        PKCS10CertificationRequestBuilder builder = new PKCS10CertificationRequestBuilder(new X500Name(subject),SubjectPublicKeyInfo.getInstance(kp.getPublic().getEncoded()));        JcaContentSignerBuilder jcaContentSignerBuilder = new JcaContentSignerBuilder(signalg);        jcaContentSignerBuilder.setProvider(provider);        ContentSigner contentSigner = jcaContentSignerBuilder.build(kp.getPrivate());        builder.build(contentSigner);        return builder.toString();    }