code: public static X509Certificate genCertificateByStr(String x509CertString) {
  		X509Certificate x509Cert = null;
  		try {
  			CertificateFactory cf = CertificateFactory.getInstance("X.509", "BC"); 
  			InputStream tIn = new ByteArrayInputStream(
  					x509CertString.getBytes("ISO-8859-1"));
  			x509Cert = (X509Certificate) cf.generateCertificate(tIn);
  		} catch (Exception e) {
  			LogUtil.writeErrorLog("gen certificate error", e);			
  		}
  		return x509Cert;
  	}
docs: 将字符串转换为X509Certificate对象.
  
  @param x509CertString
  @return