org.xhtmlrenderer.extend
Interface UserAgentCallback

All Known Implementing Classes:

DelegatingUserAgent, NaiveUserAgent

public interface UserAgentCallback

To be implemented by any user agent using the panel. "User agent" is a term defined by the W3C in the documentation for XHTML and CSS; in most cases, you can think of this as the rendering component for a browser.

This interface defines a simple callback mechanism for Flying Saucer to interact with a user agent. The FS toolkit provides a default implementation for this interface which in most cases you can leave as is. You can provide your own UserAgentCallback when constructing an XHTMLPanel or BasicPanel.

The user agent in this case is responsible for retrieving external resources. For privacy reasons, if using the library in an application that can access URIs in an unrestricted fashion, you may decide to restrict access to XML, CSS or images retrieved from external sources; that's one of the purposes of the UAC.

To understand how to create your own UAC, it's best to look at some of the implemetations shipped with the library, like the NaiveUserAgent.

Author:

Torbjoern Gannholm

Method Summary

String	getBaseURL()
byte[]	getBinaryResource(String uri) Retrieves a binary resource located at a given URI and returns its contents as a byte array or null if the resource could not be loaded.
CSSResource	getCSSResource(String uri) Retrieves the CSS at the given URI.
ImageResource	getImageResource(String uri) Retrieves the Image at the given URI.
XMLResource	getXMLResource(String uri) Retrieves the XML at the given URI.
boolean	isVisited(String uri) Normally, returns true if the user agent has visited this URI.
String	resolveURI(String uri) Used to find a uri that may be relative to the BaseURL.
void	setBaseURL(String url) Does not need to be a correct URL, only an identifier that the implementation can resolve.

Method Detail

getCSSResource

CSSResource getCSSResource(String uri)

Retrieves the CSS at the given URI. This is a synchronous call.

Parameters:

uri - Location of the CSS

Returns:

A CSSResource for the content at the URI.

getImageResource

ImageResource getImageResource(String uri)

Retrieves the Image at the given URI. This is a synchronous call.

Parameters:

uri - Location of the image

Returns:

An ImageResource for the content at the URI.

getXMLResource

XMLResource getXMLResource(String uri)

Retrieves the XML at the given URI. This is a synchronous call.

Parameters:

uri - Location of the XML

Returns:

A XMLResource for the content at the URI.

getBinaryResource

byte[] getBinaryResource(String uri)

Retrieves a binary resource located at a given URI and returns its contents as a byte array or null if the resource could not be loaded.

isVisited

boolean isVisited(String uri)

Normally, returns true if the user agent has visited this URI. UserAgent should consider if it should answer truthfully or not for privacy reasons.

Parameters:

uri - A URI which may have been visited by this user agent.

Returns:

The visited value

setBaseURL

void setBaseURL(String url)

Does not need to be a correct URL, only an identifier that the implementation can resolve.

Parameters:

url - A URL against which relative references can be resolved.

getBaseURL

String getBaseURL()

Returns:

the base uri, possibly in the implementations private uri-space

resolveURI

String resolveURI(String uri)

Used to find a uri that may be relative to the BaseURL. The returned value will always only be used via methods in the same implementation of this interface, therefore may be a private uri-space.

Parameters:

uri - an absolute or relative (to baseURL) uri to be resolved.

Returns:

the full uri in uri-spaces known to the current implementation.