Package com.exedio.cope.pattern

Class MediaServlet

java.lang.Object

javax.servlet.GenericServlet

javax.servlet.http.HttpServlet

com.exedio.cope.pattern.MediaServlet

All Implemented Interfaces:

Serializable, Servlet, ServletConfig

public class MediaServlet
extends HttpServlet

A servlet providing access to the contents of MediaPath and its subclasses. In order to use it, you have to deploy the servlet in your web.xml, providing the name of the cope model via an init-parameter. Typically, your web.xml would contain a snippet like this:

 <servlet>
    <servlet-name>media</servlet-name>
    <servlet-class>com.exedio.cope.pattern.MediaServlet</servlet-class>
    <init-param>
       <param-name>model</param-name>
       <param-value>com.exedio.shop.Main#model</param-value>
    </init-param>
 </servlet>
 <servlet-mapping>
    <servlet-name>media</servlet-name>
    <url-pattern>/media/*</url-pattern>
 </servlet-mapping>
 

Author:

Ralf Wiebicke

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor	Description
MediaServlet()

Method Summary

Modifier and Type	Method	Description
void	destroy()
protected boolean	doFlushBufferOnNotModified(MediaPath path, Item item)	Tomcat automatically adds Content-Length: 0 to the response if the response body is smaller than the buffer size.
protected void	doGet(HttpServletRequest request, HttpServletResponse response)
protected Duration	getMaximumAge(MediaPath path, Item item)	Let this method return the maximum age, that will be put into header Cache-Control: max-age=<seconds> of the response.
void	init()
void	initConnected(Model model)
protected boolean	isAccessControlAllowOriginWildcard(MediaPath path, Item item)	Let this method return true, if you want to add a header Access-Control-Allow-Origin: * to the response.
protected boolean	isCacheControlPrivate(MediaPath path, Item item)	Let this method return true, if you want to add a header Cache-Control: private to the response.
protected void	onException(HttpServletRequest request, Exception exception)

Methods inherited from class javax.servlet.http.HttpServlet

doDelete, doHead, doOptions, doPost, doPut, doTrace, getLastModified, service, service

Methods inherited from class javax.servlet.GenericServlet

getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, log, log

Methods inherited from class java.lang.Object

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

Constructor Detail

MediaServlet

public MediaServlet()

Method Detail

init

public final void init()
                throws ServletException

Overrides:

init in class GenericServlet

Throws:

ServletException

initConnected

public void initConnected(Model model)

destroy

public final void destroy()

Specified by:

destroy in interface Servlet

Overrides:

destroy in class GenericServlet

doGet

protected final void doGet(HttpServletRequest request,
                           HttpServletResponse response)
                    throws IOException

Overrides:

doGet in class HttpServlet

Throws:

IOException

getMaximumAge

protected Duration getMaximumAge(MediaPath path,
                                 Item item)

Let this method return the maximum age, that will be put into header Cache-Control: max-age=<seconds> of the response. If method returns null, no maximum age is sent. Negative values are treated like zero. Fractional seconds are ignored. This method is not called for @UrlFingerPrinting pathes - such pathes do send a maximum age of 363 days.

The default implementation returns ConnectProperties.getMediaServletMaximumAge().

See RFC 2616 Section 14.9.3 Modifications of the Basic Expiration Mechanism, https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/Expiration.html#ExpirationDownloadDist .

Parameters:

path - the media path of the current request

item - the item of the current request

isCacheControlPrivate

protected boolean isCacheControlPrivate(MediaPath path,
                                        Item item)

Let this method return true, if you want to add a header Cache-Control: private to the response. This forbids shared caches, such as company proxies to cache such urls.

The default implementation returns true iff url guessing is prevented.

See RFC 2616 Section 14.9.1 What is Cacheable, https://httpd.apache.org/docs/2.2/mod/mod_cache.html#cachestoreprivate , and https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/Expiration.html#ExpirationDownloadDist .

Parameters:

path - the media path of the current request

item - the item of the current request

isAccessControlAllowOriginWildcard

protected boolean isAccessControlAllowOriginWildcard(MediaPath path,
                                                     Item item)

Let this method return true, if you want to add a header Access-Control-Allow-Origin: * to the response. This is typically needed for fonts served from a different domain. The default implementation returns false.

Parameters:

path - the media path of the current request

item - the item of the current request

doFlushBufferOnNotModified

protected boolean doFlushBufferOnNotModified(MediaPath path,
                                             Item item)

Tomcat automatically adds Content-Length: 0 to the response if the response body is smaller than the buffer size. Unfortunately it does so for 304 responses as well. Apache 2.4 does not accept 304 responses with a Content-Length unequal to the original 200 response. The call to flushBuffer prevents Tomcat from adding a Content-Length header to the response. Of course, this is a hot fix. Remove it, if you find a better solution to avoid the Content-Length header.

Parameters:

path - the media path of the current request

item - the item of the current request

onException

protected void onException(HttpServletRequest request,
                           Exception exception)