com.day.cq.wcm.commons

Class AbstractImageServlet

java.lang.Object

GenericServlet

org.apache.sling.api.servlets.SlingSafeMethodsServlet

com.day.cq.wcm.commons.AbstractImageServlet

public abstract class AbstractImageServlet
extends SlingSafeMethodsServlet

Servers as base for image servlets

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	AbstractImageServlet.ImageContext Convenience class that holds useful stuff needed for image generation

Constructor Summary

Constructors

Constructor and Description
AbstractImageServlet()

Method Summary

Methods

Modifier and Type	Method and Description
protected boolean	applyDiff(Layer layer, AbstractImageServlet.ImageContext c) Default behavior that applies diff information to the layer
protected boolean	checkModifiedSince(SlingHttpServletRequest req, SlingHttpServletResponse resp) Checks if the request contains a if-last-modified-since header and if the node has a jcr:lastModified property.
protected ImageResource	createImageResource(Resource resource) Creates an image resource based on the resource in the image context.
protected abstract Layer	createLayer(AbstractImageServlet.ImageContext c) Creates the image layer.
protected void	doGet(SlingHttpServletRequest request, SlingHttpServletResponse response) Handles a GET request and created the desired image.
protected double	getImageQuality() Returns the image quality.
protected java.lang.String	getImageType() Returns the image type.
protected java.lang.String	getImageType(java.lang.String ext) Returns the image type for the given extension.
protected boolean	isModifiedDiff(AbstractImageServlet.ImageContext c) Calculates if the underlying image was modified in respect to the versioned diff.
protected void	writeLayer(SlingHttpServletRequest request, SlingHttpServletResponse response, AbstractImageServlet.ImageContext context, Layer layer) Writes the layer to the response.
protected void	writeLayer(SlingHttpServletRequest request, SlingHttpServletResponse response, AbstractImageServlet.ImageContext context, Layer layer, double quality) Writes the layer to the response at the specified quality.

Methods inherited from class org.apache.sling.api.servlets.SlingSafeMethodsServlet

doGeneric, doHead, doOptions, doTrace, getAllowedRequestMethods, getServletInfo, handleMethodNotImplemented, mayService, service, service

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractImageServlet

public AbstractImageServlet()

Method Detail

doGet

protected void doGet(SlingHttpServletRequest request,
         SlingHttpServletResponse response)
              throws ServletException,
                     java.io.IOException

Handles a GET request and created the desired image. calls the following methods:

• checkModifiedSince(SlingHttpServletRequest, SlingHttpServletResponse)
• createLayer(ImageContext)
• writeLayer(SlingHttpServletRequest, SlingHttpServletResponse, ImageContext, Layer)

If the requested extension does not map to a known image type via getImageType(String), a 404 is responded.

Overrides:

doGet in class SlingSafeMethodsServlet

Parameters:

request - The HTTP request

response - The HTTP response

Throws:

ServletException - Not thrown by this implementation.

java.io.IOException - If the error status cannot be reported back to the client.

writeLayer

protected void writeLayer(SlingHttpServletRequest request,
              SlingHttpServletResponse response,
              AbstractImageServlet.ImageContext context,
              Layer layer)
                   throws java.io.IOException,
                          RepositoryException

Writes the layer to the response.

Parameters:

request - servlet request

response - servlet response

context - the context

layer - layer

Throws:

java.io.IOException - if an I/O error occurs.

RepositoryException - if an repository error occurs.

writeLayer

protected void writeLayer(SlingHttpServletRequest request,
              SlingHttpServletResponse response,
              AbstractImageServlet.ImageContext context,
              Layer layer,
              double quality)
                   throws java.io.IOException,
                          RepositoryException

Writes the layer to the response at the specified quality.

Parameters:

request - servlet request

response - servlet response

context - the context

layer - layer

quality - image quality

Throws:

java.io.IOException - if an I/O error occurs.

RepositoryException - if an repository error occurs.

getImageType

protected java.lang.String getImageType()

Returns the image type. default "image/png"

Returns:

the image type.

getImageType

protected java.lang.String getImageType(java.lang.String ext)

Returns the image type for the given extension. currently there are only "png", "gif" and "jpg" supported, but an subclass can provide other mappings.

Parameters:

ext - the extension

Returns:

the image type or null.

getImageQuality

protected double getImageQuality()

Returns the image quality. default 1.0

Returns:

the image quality.

checkModifiedSince

protected boolean checkModifiedSince(SlingHttpServletRequest req,
                         SlingHttpServletResponse resp)

Checks if the request contains a if-last-modified-since header and if the node has a jcr:lastModified property. if the properties were modified before the header a 304 is sent otherwise the response last modified header is set. If the give doesn't have the property, the parent node is searched.

Parameters:

req - the request

resp - the response

Returns:

true if the response was sent

createLayer

protected abstract Layer createLayer(AbstractImageServlet.ImageContext c)
                              throws RepositoryException,
                                     java.io.IOException

Creates the image layer.

Parameters:

c - the convenience context

Returns:

the layer

Throws:

RepositoryException - if an error occurs.

java.io.IOException - if an I/O error occurs

applyDiff

protected boolean applyDiff(Layer layer,
                AbstractImageServlet.ImageContext c)

Default behavior that applies diff information to the layer

Parameters:

layer - the layer

c - the context

Returns:

true if the layer was modified.

createImageResource

protected ImageResource createImageResource(Resource resource)

Creates an image resource based on the resource in the image context. Subclasses can override this to create extended variants of image resources.

Parameters:

resource - the resource

Returns:

the image resource

isModifiedDiff

protected boolean isModifiedDiff(AbstractImageServlet.ImageContext c)

Calculates if the underlying image was modified in respect to the versioned diff.

Parameters:

c - the image context

Returns:

true if modified