Class GenericFilter

java/jakarta/servlet/GenericFilter.java:32–100

Provides a base class that implements the Filter and FilterConfig interfaces to reduce boilerplate when writing new filters. @see jakarta.servlet.Filter @see jakarta.servlet.FilterConfig @since Servlet 4.0

 * @since Servlet 4.0
 */
public abstract class GenericFilter implements Filter, FilterConfig, Serializable {

    @Serial
    private static final long serialVersionUID = 1L;

   /**
      * The filter configuration.
      */
    private volatile FilterConfig filterConfig;

    /**
      * Constructs a new GenericFilter.
      */
    public GenericFilter() {
        // NO-OP
    }


    @Override
    public String getInitParameter(String name) {
        return getFilterConfig().getInitParameter(name);
    }


    @Override
    public Enumeration<String> getInitParameterNames() {
        return getFilterConfig().getInitParameterNames();
    }


    /**
     * Obtain the FilterConfig used to initialise this Filter instance.
     *
     * @return The config previously passed to the {@link #init(FilterConfig)} method
     */
    public FilterConfig getFilterConfig() {
        return filterConfig;
    }


    @Override
    public ServletContext getServletContext() {
        return getFilterConfig().getServletContext();
    }


    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        this.filterConfig = filterConfig;
        init();
    }


    /**
     * Convenience method for subclasses to save them having to call <code>super.init(config)</code>. This is a NO-OP by
     * default.
     *
     * @throws ServletException If an exception occurs that interrupts the Filter's normal operation