Package org.omnifaces.filter

Class HttpFilter

java.lang.Object

org.omnifaces.filter.HttpFilter

All Implemented Interfaces:

Filter

Direct Known Subclasses:

CacheControlFilter, CharacterEncodingFilter, FacesExceptionFilter, FacesViewsForwardingFilter, GzipResponseFilter, MutableRequestFilter, OnDemandResponseBufferFilter

public abstract class HttpFilter
extends Object
implements Filter

The HttpFilter is abstract filter specifically for HTTP requests. It provides a convenient abstract doFilter(HttpServletRequest, HttpServletResponse, HttpSession, FilterChain) method directly providing the HTTP servlet request, response and session, so that there's no need to cast them everytime in the doFilter(ServletRequest, ServletResponse, FilterChain) implementation. Also, default implementations of init(FilterConfig) and destroy() are provided, so that there's no need to implement them every time even when not really needed.

It's a bit the idea of using the convenient HttpServlet abstract servlet class instead of the barebones Servlet interface.

Usage

To use it, just let your custom filter extend from HttpFilter instead of implement Filter. For example:

 @WebFilter("/app/*")
 public class LoginFilter extends HttpFilter {

     @Override
     public void doFilter(HttpServletRequest request, HttpServletResponse response, HttpSession session, FilterChain chain)
         throws ServletException, IOException
     {
         if (session != null && session.getAttribute("user") != null) {
             chain.doFilter(request, response);
         }
         else {
             Servlets.facesRedirect(request, response, "login.xhtml");
         }
     }
 }
 

Author:

Arjan Tijms, Bauke Scholtz

Constructor Summary

Constructors

Constructor	Description
HttpFilter()

Method Summary

Modifier and Type	Method	Description
void	destroy()
abstract void	doFilter(HttpServletRequest request, HttpServletResponse response, HttpSession session, FilterChain chain)	Filter the HTTP request.
void	doFilter(ServletRequest request, ServletResponse response, FilterChain chain)
protected FilterConfig	getFilterConfig()	Returns the filter config.
protected String	getInitParameter(String name)	Returns the value of the filter init parameter associated with the given name.
protected ServletContext	getServletContext()	Returns the servlet context.
void	init()	Convenience init() method without FilterConfig parameter which will be called by init(FilterConfig).
void	init(FilterConfig filterConfig)	Called by the servlet container when the filter is about to be placed into service.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

HttpFilter

public HttpFilter()

Method Detail

init

public void init(FilterConfig filterConfig)
          throws ServletException

Called by the servlet container when the filter is about to be placed into service. This implementation stores the FilterConfig object for later use by the getter methods. It's recommended to not override this method. Instead, just use init() method. When overriding this method anyway, don't forget to call super.init(config), otherwise the getter methods will throw an illegal state exception.

Specified by:

init in interface Filter

Throws:

ServletException

init

public void init()
          throws ServletException

Convenience init() method without FilterConfig parameter which will be called by init(FilterConfig).

Throws:

ServletException - When filter's initialization failed.

doFilter

public void doFilter(ServletRequest request,
                     ServletResponse response,
                     FilterChain chain)
              throws ServletException,
                     IOException

Specified by:

doFilter in interface Filter

Throws:

ServletException

IOException

doFilter

public abstract void doFilter(HttpServletRequest request,
                              HttpServletResponse response,
                              HttpSession session,
                              FilterChain chain)
                       throws ServletException,
                              IOException

Filter the HTTP request. The session argument is null if there is no session.

Parameters:

request - The HTTP request.

response - The HTTP response.

session - The HTTP session, if any, else null.

chain - The filter chain to continue.

Throws:

ServletException - As wrapper exception when something fails in the request processing.

IOException - Whenever something fails at I/O level.

See Also:

Filter.doFilter(ServletRequest, ServletResponse, FilterChain)

destroy

public void destroy()

Specified by:

destroy in interface Filter

getFilterConfig

protected FilterConfig getFilterConfig()

Returns the filter config.

Returns:

The filter config.

getInitParameter

protected String getInitParameter(String name)

Returns the value of the filter init parameter associated with the given name.

Parameters:

name - The filter init parameter name to return the associated value for.

Returns:

The value of the filter init parameter associated with the given name.

getServletContext

protected ServletContext getServletContext()

Returns the servlet context.

Returns:

The servlet context.