apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/spi/configuration/LdapProperties.java/LdapProperties/determinePort
class LdapProperties:  private int determinePort(Environment environment) {
    Assert.notNull(environment, "Environment must not be null");
    String localPort = environment.getProperty("local.ldap.port");
    if (localPort != null) {
      return Integer.parseInt(localPort);
    }
    return DEFAULT_PORT;
  }