NaiveUserAgent (Flying Saucer Core Renderer 9.0.8 API)

java.lang.Object
- org.xhtmlrenderer.swing.NaiveUserAgent

All Implemented Interfaces:

DocumentListener, UserAgentCallback
```
public class NaiveUserAgent
extends 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.

Author:

Torbjoern Gannholm

Field Summary

Fields
Modifier and Type Field and Description

protected LinkedHashMap _imageCache
a (simple) LRU cache

Fields
Modifier and Type	Field and Description
`protected LinkedHashMap`	`_imageCache` a (simple) LRU cache

Constructor Summary

Constructors
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.

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`clearImageCache()` Empties the image cache entirely.
`protected ImageResource`	`createImageResource(String uri, Image img)` Factory method to generate ImageResources from a given Image.
`void`	`documentLoaded()` Indicates document layout has complete, e.g.
`void`	`documentStarted()` Indicates document has been requested (e.g.
`String`	`getBaseURL()` Returns the current baseUrl for this class.
`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 located at the given URI.
`ImageResource`	`getImageResource(String uri)` Retrieves the image located at the given URI.
`XMLResource`	`getXMLResource(String uri)` Retrieves the XML located at the given URI.
`boolean`	`isVisited(String uri)` Returns true if the given URI was visited, meaning it was requested at some point since initialization.
`void`	`onLayoutException(Throwable t)` Called when document layout failed with an exception.
`void`	`onRenderException(Throwable t)` Called when document render failed with an exception.
`protected InputStream`	`resolveAndOpenStream(String uri)` Gets a Reader for the resource identified
`String`	`resolveURI(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(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.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - _imageCache
```
protected LinkedHashMap _imageCache
```
    a (simple) LRU cache
- Constructor Detail
  - NaiveUserAgent
```
public NaiveUserAgent()
```
    Creates a new instance of NaiveUserAgent with a max image cache of 16 images.
  - NaiveUserAgent
```
public NaiveUserAgent(int imgCacheSize)
```
    Creates a new NaiveUserAgent with a cache of a specific size.
    
    Parameters:
    imgCacheSize - Number of images to hold in cache before LRU images are released.
- Method Detail
  - shrinkImageCache
```
public 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.
  - clearImageCache
```
public void clearImageCache()
```
    Empties the image cache entirely.
  - resolveAndOpenStream
```
protected InputStream resolveAndOpenStream(String uri)
```
    Gets a Reader for the resource identified
    
    Parameters:
    uri - PARAM
    
    Returns:
    The stylesheet value
  - getCSSResource
```
public CSSResource getCSSResource(String uri)
```
    Retrieves the CSS located at the given URI. It's assumed the URI does point to a CSS file--the URI will be accessed (using java.io or java.net), opened, read and then passed into the CSS parser. The result is packed up into an CSSResource for later consumption.
    
    Specified by:
    
    getCSSResource in interface UserAgentCallback
    
    Parameters:
    uri - Location of the CSS source.
    
    Returns:
    A CSSResource containing the parsed CSS.
  - getImageResource
```
public ImageResource getImageResource(String uri)
```
    Retrieves the image located at the given URI. It's assumed the URI does point to an image--the URI will be accessed (using java.io or java.net), opened, read and then passed into the JDK image-parsing routines. The result is packed up into an ImageResource for later consumption.
    
    Specified by:
    
    getImageResource in interface UserAgentCallback
    
    Parameters:
    uri - Location of the image source.
    
    Returns:
    An ImageResource containing the image.
  - createImageResource
```
protected ImageResource createImageResource(String uri,
                                Image img)
```
    Factory method to generate ImageResources from a given Image. May be overridden in subclass.
    
    Parameters:
    uri - The URI for the image, resolved to an absolute URI.
    img - The image to package; may be null (for example, if image could not be loaded).
    
    Returns:
    An ImageResource containing the image.
  - getXMLResource
```
public XMLResource getXMLResource(String uri)
```
    Retrieves the XML located at the given URI. It's assumed the URI does point to a XML--the URI will be accessed (using java.io or java.net), opened, read and then passed into the XML parser (XMLReader) configured for Flying Saucer. The result is packed up into an XMLResource for later consumption.
    
    Specified by:
    
    getXMLResource in interface UserAgentCallback
    
    Parameters:
    uri - Location of the XML source.
    
    Returns:
    An XMLResource containing the image.
  - getBinaryResource
```
public byte[] getBinaryResource(String uri)
```
    Description copied from interface: UserAgentCallback
    
    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.
    
    Specified by:
    
    getBinaryResource in interface UserAgentCallback
  - isVisited
```
public boolean isVisited(String uri)
```
    Returns true if the given URI was visited, meaning it was requested at some point since initialization.
    
    Specified by:
    
    isVisited in interface UserAgentCallback
    
    Parameters:
    uri - A URI which might have been visited.
    
    Returns:
    Always false; visits are not tracked in the NaiveUserAgent.
  - setBaseURL
```
public void setBaseURL(String url)
```
    URL relative to which URIs are resolved.
    
    Specified by:
    
    setBaseURL in interface UserAgentCallback
    
    Parameters:
    url - A URI which anchors other, possibly relative URIs.
  - resolveURI
```
public String resolveURI(String uri)
```
    Resolves the URI; if absolute, leaves as is, if relative, returns an absolute URI based on the baseUrl for the agent.
    
    Specified by:
    
    resolveURI in interface UserAgentCallback
    
    Parameters:
    uri - A URI, possibly relative.
    
    Returns:
    A URI as String, resolved, or null if there was an exception (for example if the URI is malformed).
  - getBaseURL
```
public String getBaseURL()
```
    Returns the current baseUrl for this class.
    
    Specified by:
    
    getBaseURL in interface UserAgentCallback
    
    Returns:
    the base uri, possibly in the implementations private uri-space
  - documentStarted
```
public void documentStarted()
```
    Description copied from interface: DocumentListener
    
    Indicates document has been requested (e.g. a new document is going to be loaded). This will be called before any activity takes place for the document.
    
    Specified by:
    
    documentStarted in interface DocumentListener
  - documentLoaded
```
public void documentLoaded()
```
    Description copied from interface: DocumentListener
    
    Indicates document layout has complete, e.g. document is fully "loaded" for display; this is not a callback for the document source (e.g. XML) being loaded. This method will be called on every layout run (including, for example, after panel resizes).
    
    Specified by:
    
    documentLoaded in interface DocumentListener
  - onLayoutException
```
public void onLayoutException(Throwable t)
```
    Description copied from interface: DocumentListener
    
    Called when document layout failed with an exception. All 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.
    
    Specified by:
    
    onLayoutException in interface DocumentListener
  - onRenderException
```
public void onRenderException(Throwable t)
```
    Description copied from interface: DocumentListener
    
    Called when document render failed with an exception. All 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.
    
    Specified by:
    
    onRenderException in interface DocumentListener

Class NaiveUserAgent

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

_imageCache

Constructor Detail

NaiveUserAgent

NaiveUserAgent

Method Detail

shrinkImageCache

clearImageCache

resolveAndOpenStream

getCSSResource

getImageResource

createImageResource

getXMLResource

getBinaryResource

isVisited

setBaseURL

resolveURI

getBaseURL

documentStarted

documentLoaded

onLayoutException

onRenderException