private Class<? extends WebEnvironment> webEnvironmentClassFromServletContext(ServletContext servletContext) {

        Class<? extends WebEnvironment> webEnvironmentClass = null;
        String className = servletContext.getInitParameter(ENVIRONMENT_CLASS_PARAM);
        if (className != null) {
            try {
                webEnvironmentClass = ClassUtils.forName(className);
            } catch (UnknownClassException ex) {
                throw new ConfigurationException(
                        "Failed to load custom WebEnvironment class [" + className + "]", ex);
            }
        }
        return webEnvironmentClass;
    }
Return the WebEnvironment implementation class to use, either the default
{@link IniWebEnvironment} or a custom class if specified.

@param servletContext current servlet context
@return the WebEnvironment implementation class to use
@see #ENVIRONMENT_CLASS_PARAM
@see IniWebEnvironment
@see #determineWebEnvironment(ServletContext)
@see #getDefaultWebEnvironmentClass(ServletContext)
@deprecated This method is not longer used by Shiro, and will be removed in future versions,
use {@link #determineWebEnvironment(ServletContext)} or {@link #determineWebEnvironment(ServletContext)}
web/src/main/java/org/apache/shiro/web/env/EnvironmentLoader.java