public class NaiveUserAgent extends java.lang.Object implements UserAgentCallback, DocumentListener
NaiveUserAgent is a simple implementation of UserAgentCallback
which places no restrictions on what
XML, CSS or images are loaded, and reports visited links without any filtering. The most straightforward process
available in the JDK is used to load the resources in question--either using java.io or java.net classes.
The NaiveUserAgent has a small cache for images,
the size of which (number of images) can be passed as a constructor argument. There is no automatic cleaning of
the cache; call shrinkImageCache()
to remove the least-accessed elements--for example, you might do this
when a new document is about to be loaded. The NaiveUserAgent is also a DocumentListener; if registered with a
source of document events (like the panel hierarchy), it will respond to the
DocumentListener.documentStarted()
call and attempt to shrink its cache.
This class is meant as a starting point--it will work out of the box, but you should really implement your own, tuned to your application's needs.
Constructor and Description |
---|
NaiveUserAgent()
Creates a new instance of NaiveUserAgent with a max image cache of 16 images.
|
NaiveUserAgent(int imgCacheSize)
Creates a new NaiveUserAgent with a cache of a specific size.
|
Modifier and Type | Method and Description |
---|---|
void |
clearImageCache()
Empties the image cache entirely.
|
void |
documentLoaded()
Indicates document layout has complete, e.g.
|
void |
documentStarted()
Indicates document has been requested (e.g.
|
java.lang.String |
getBaseURL()
Returns the current baseUrl for this class.
|
byte[] |
getBinaryResource(java.lang.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(java.lang.String uri)
Retrieves the CSS located at the given URI.
|
ImageResource |
getImageResource(java.lang.String uri)
Retrieves the image located at the given URI.
|
XMLResource |
getXMLResource(java.lang.String uri)
Retrieves the XML located at the given URI.
|
boolean |
isVisited(java.lang.String uri)
Returns true if the given URI was visited, meaning it was requested at some point since initialization.
|
void |
onLayoutException(java.lang.Throwable t)
Called when document layout failed with an exception.
|
void |
onRenderException(java.lang.Throwable t)
Called when document render failed with an exception.
|
java.lang.String |
resolveURI(java.lang.String uri)
Resolves the URI; if absolute, leaves as is, if relative, returns an absolute URI based on the baseUrl for
the agent.
|
void |
setBaseURL(java.lang.String url)
URL relative to which URIs are resolved.
|
void |
shrinkImageCache()
If the image cache has more items than the limit specified for this class, the least-recently used will
be dropped from cache until it reaches the desired size.
|
public NaiveUserAgent()
public NaiveUserAgent(int imgCacheSize)
imgCacheSize
- Number of images to hold in cache before LRU images are released.public void shrinkImageCache()
public void clearImageCache()
public CSSResource getCSSResource(java.lang.String uri)
getCSSResource
in interface UserAgentCallback
uri
- Location of the CSS source.public ImageResource getImageResource(java.lang.String uri)
getImageResource
in interface UserAgentCallback
uri
- Location of the image source.public XMLResource getXMLResource(java.lang.String uri)
getXMLResource
in interface UserAgentCallback
uri
- Location of the XML source.public byte[] getBinaryResource(java.lang.String uri)
UserAgentCallback
null
if the resource could not be loaded.getBinaryResource
in interface UserAgentCallback
public boolean isVisited(java.lang.String uri)
isVisited
in interface UserAgentCallback
uri
- A URI which might have been visited.public void setBaseURL(java.lang.String url)
setBaseURL
in interface UserAgentCallback
url
- A URI which anchors other, possibly relative URIs.public java.lang.String resolveURI(java.lang.String uri)
resolveURI
in interface UserAgentCallback
uri
- A URI, possibly relative.public java.lang.String getBaseURL()
getBaseURL
in interface UserAgentCallback
public void documentStarted()
DocumentListener
documentStarted
in interface DocumentListener
public void documentLoaded()
DocumentListener
documentLoaded
in interface DocumentListener
public void onLayoutException(java.lang.Throwable t)
DocumentListener
Throwable
objects thrown (except for
ThreadDeath
) during layout and not otherwise handled will
be provided to this method. If a DocumentListener
has been
defined an XHTML panel, the listener is entirely responsible for
handling the exception. No other action will be taken.onLayoutException
in interface DocumentListener
public void onRenderException(java.lang.Throwable t)
DocumentListener
Throwable
objects thrown (except for
ThreadDeath
) during render and not otherwise handled will
be provided to this method. If a DocumentListener
has been
defined an XHTML panel, the listener is entirely responsible for
handling the exception. No other action will be taken.onRenderException
in interface DocumentListener