spring如何优雅的读取证书文件

        //idea可以，jar不可以
        InputStream inputStream=this.getClass().getResourceAsStream("ca.cer.txt");
        System.out.println(">>>>cer>>>>>>>>"+inputStream);
        
         //idea可以，jar可以，注意路径不要出现resource
        ClassPathResource res = new ClassPathResource("ca.cer");
        System.out.println(">>>>res>>>>>>>>"+res.getInputStream());

        CertificateFactory cf = CertificateFactory.getInstance("X.509");
        X509Certificate cert = (X509Certificate)cf.generateCertificate(res.getInputStream());
        System.out.println(">>>>509>>>>>>>>"+cert.toString());
        System.out.println(">>>>509>>>>>>>>"+cert.getSubjectDN());