net.sourceforge.stripes.controller

Class DynamicMappingFilter

java.lang.Object

net.sourceforge.stripes.controller.DynamicMappingFilter

All Implemented Interfaces:

javax.servlet.Filter

public class DynamicMappingFilter
extends java.lang.Object
implements javax.servlet.Filter

A servlet filter that dynamically maps URLs to ActionBeans. This filter can be used to allow Stripes to dispatch requests to ActionBeans based on their URL binding, even if the URL to which they are bound is not explicitly mapped in web.xml.

There are a few caveats that must be observed when using this filter:

• StripesFilter MUST be defined in web.xml so that it will be loaded and initialized.
• This filter MUST be mapped to /* to work correctly.
• This filter MUST be the last filter in the filter chain. When it dynamically maps an ActionBean to a URL, the filter chain is interrupted.

StripesFilter and DispatcherServlet need not be mapped to any URL patterns in web.xml since this filter will determine at runtime whether or not they need to be invoked. In fact, you don't even need to define DispatcherServlet in web.xml at all because this filter uses an instance it creates and manages internally. However, some resources, such as JSPs, may require access to the Stripes Configuration. Thus, StripesFilter should be mapped to *.jsp if you intend to access JSPs directly.

This filter takes the following approach to determining when to dispatch an ActionBean:

1. Allow the request to process normally, trapping any HTTP errors that are returned.
2. If no error was returned then do nothing, allowing the request to complete successfully. If any error other than 404 was returned then send the error through. Otherwise ...
3. Check the ActionResolver to see if an ActionBean is mapped to the URL. If not, then send the 404 error through. Otherwise...
4. Invoke StripesFilter and DispatcherServlet

One benefit of this approach is that static resources can be delivered from the same namespace to which an ActionBean is mapped using clean URLs. (Form more information on clean URLs, see UrlBinding.) For example, if your UserActionBean is mapped to @UrlBinding("/user/{id}/{$event}") and you have a static file at /user/icon.gif, then your icon will be delivered correctly because the initial request will not have returned a 404 error.

This filter accepts one init-param. IncludeBufferSize (optional, default 1024) sets the number of characters to be buffered by DynamicMappingFilter.TempBufferWriter for include requests. See DynamicMappingFilter.TempBufferWriter for more information.

This is the suggested mapping for this filter in web.xml.

  <filter>
      <description>Dynamically maps URLs to ActionBeans.</description>
      <display-name>Stripes Dynamic Mapping Filter</display-name>
      <filter-name>DynamicMappingFilter</filter-name>
      <filter-class>
          net.sourceforge.stripes.controller.DynamicMappingFilter
      </filter-class>
  </filter>
  
  <filter-mapping>
      <filter-name>DynamicMappingFilter</filter-name>
      <url-pattern>/*</url-pattern>
      <dispatcher>REQUEST</dispatcher>
      <dispatcher>FORWARD</dispatcher>
      <dispatcher>INCLUDE</dispatcher>
  </filter-mapping>
 

Since:

Stripes 1.5

Author:

Ben Gunter

See Also:

UrlBinding

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	DynamicMappingFilter.ErrorTrappingResponseWrapper An HttpServletResponseWrapper that traps HTTP errors by overriding sendError(int, ..).
static class	DynamicMappingFilter.TempBufferWriter A Writer that passes characters to a PrintWriter.

Constructor Summary

Constructors

Constructor and Description
DynamicMappingFilter()

Method Summary

Methods

Modifier and Type	Method and Description
void	destroy()
void	doFilter(javax.servlet.ServletRequest request, javax.servlet.ServletResponse response, javax.servlet.FilterChain chain)
protected void	doOneTimeConfiguration() Perform initialization that can't be done in init(..).
protected java.lang.String	getRequestURI(javax.servlet.http.HttpServletRequest request) Deprecated. Use HttpUtil.getRequestedPath(HttpServletRequest) instead.
void	init(javax.servlet.FilterConfig config)

Methods inherited from class java.lang.Object

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

Constructor Detail

DynamicMappingFilter

public DynamicMappingFilter()

Method Detail

init

public void init(javax.servlet.FilterConfig config)
          throws javax.servlet.ServletException

Specified by:

init in interface javax.servlet.Filter

Throws:

javax.servlet.ServletException

destroy

public void destroy()

Specified by:

destroy in interface javax.servlet.Filter

doFilter

public void doFilter(javax.servlet.ServletRequest request,
            javax.servlet.ServletResponse response,
            javax.servlet.FilterChain chain)
              throws java.io.IOException,
                     javax.servlet.ServletException

Specified by:

doFilter in interface javax.servlet.Filter

Throws:

java.io.IOException

javax.servlet.ServletException

doOneTimeConfiguration

protected void doOneTimeConfiguration()
                               throws javax.servlet.ServletException

Perform initialization that can't be done in init(..). This is normally called only once, on the first invocation of doFilter(..).

Throws:

javax.servlet.ServletException

getRequestURI

@Deprecated
protected java.lang.String getRequestURI(javax.servlet.http.HttpServletRequest request)

Deprecated. Use HttpUtil.getRequestedPath(HttpServletRequest) instead.

Get the context-relative URI of the current include, forward or request.