For #18 - Further work on the pluggable URI resolver and cache. Also,…

… explanation in readme.

README.md

@@ -182,6 +182,37 @@ as simple as adding the following code:
 ````
 Then use ````builder.useHttpStreamImplementation(new OkHttpStreamFactory())````.
 
+CACHE BETWEEN RUNS - INTRODUCED IN RC3
+=======
+By default, Open HTML to PDF should not cache anything between runs. However, it allows the user to plugin an external cache. It should
+be noted that the URI received by the cache is already resolved (see below). Here is a simple external cache:
+````java
+	public static class SimpleCache implements FSCache {
+		private final Map<FSCacheKey, Object> cache = new HashMap<>();
+
+		@Override
+		public Object get(FSCacheKey cacheKey) {
+			Object obj = cache.get(cacheKey);
+			System.out.println("Requesting: " + cacheKey.getUri() + " of type: " + cacheKey.getClazz().getName() + ", got it: " + (obj != null));
+			return obj;
+		}
+
+		@Override
+		public void put(FSCacheKey cacheKey, Object obj)  {
+			System.out.println("Putting: " + cacheKey.getUri() + " of type: " + cacheKey.getClazz().getName());
+			cache.put(cacheKey, obj);
+		}
+	}
+````
+Of course, you may want to customize your cache by inspecting the URI or class name contained by cache key. Once you have a cache, you can set it
+on the builder with ````builder.useCache(cache)````.
+
+URI RESOLVER - INTRODUCED IN RC3
+=======
+By default, the code attempts to resolve relative URIs by using the document URI as a base URI. Absolute URIs are returned unchanged. If you wish to plugin your
+own resolver, you can. This can not only resolve relative URIs but also resolve URIs in a private address space or even reject a URI. To use an external resolver 
+implement ````FSUriResolver```` and use it with ````builder.useUriResolver(new MyResolver())````.
+
 LOGGING
 =======
 Three options are provided by Open HTML to PDF. The default is to use java.util.logging. If you prefer to output using log4j or slf4j, adapters are provided:
@@ -224,6 +255,8 @@ CHANGELOG
 
 head - 0.0.1-RC3-SNAPSHOT
 ========
++ [Added support for plugging in an external URI resolver](https://github.com/danfickle/openhtmltopdf/issues/18)
++ [Added support for plugging in an external cache](https://github.com/danfickle/openhtmltopdf/issues/18)
 + [Added support for font fallback for Java2D](https://github.com/danfickle/openhtmltopdf/issues/10) Thanks @willamette
 + [Fixed crash issue when document contained CDATA sections](https://github.com/danfickle/openhtmltopdf/issues/16) Thanks @hiddendog
 

openhtmltopdf-core/src/main/java/com/openhtmltopdf/extend/FSUriResolver.java

@@ -1,14 +1,27 @@
 package com.openhtmltopdf.extend;
 
-
-/**
- * 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.
- *
- * @param uri an absolute or relative (to baseURL) uri to be resolved.
- * @return the full uri in uri-spaces known to the current implementation.
- */
 public interface FSUriResolver {
+
+	/**
+	 * 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.
+	 *
+	 * @param uri an absolute or relative (to baseURL) uri to be resolved.
+	 * @return the full uri in uri-spaces known to the current implementation.
+	 */
 	public String resolveURI(String uri);
+
+    /**
+     * Does not need to be a correct URL, only an identifier that the
+     * implementation can resolve.
+     *
+     * @param url A URL against which relative references can be resolved.
+     */
+	public void setBaseURL(String uri);
+
+    /**
+     * @return the base uri, possibly in the implementations private uri-space
+     */
+	public String getBaseURL();
 }

openhtmltopdf-core/src/main/java/com/openhtmltopdf/swing/NaiveUserAgent.java

@@ -76,7 +76,6 @@ public class NaiveUserAgent implements UserAgentCallback, DocumentListener {
     protected final LinkedHashMap<String, ImageResource> _imageCache = new LinkedHashMap<String, ImageResource>();
     private final FSUriResolver DEFAULT_URI_RESOLVER = new DefaultUriResolver(this); 
 
-    private String _baseURL;
     protected HttpStreamFactory _streamFactory = new DefaultHttpStreamFactory();
     protected FSCache _externalCache = new NullFSCache(false);
     protected FSUriResolver _resolver = DEFAULT_URI_RESOLVER;
@@ -420,12 +419,13 @@ public boolean isVisited(String uri) {
      */
     @Override
     public void setBaseURL(String url) {
-        _baseURL = url;
+        _resolver.setBaseURL(url);
     }
 
     public static class DefaultUriResolver implements FSUriResolver {
 
     	private final NaiveUserAgent _agent;
+    	private String _baseURI;
 
     	private DefaultUriResolver(NaiveUserAgent agent) {
     		this._agent = agent;
@@ -477,25 +477,35 @@ public String resolveURI(String uri) {
 				if (!result.isAbsolute()) {
 					XRLog.load(uri
 							+ " is not a URL; may be relative. Testing using parent URL "
-							+ _agent._baseURL);
+							+ _agent.getBaseURL());
 					result = new URI(_agent.getBaseURL()).resolve(result);
 				}
 				ret = result.toString();
 			} catch (URISyntaxException e) {
 				XRLog.exception("The default NaiveUserAgent cannot resolve the URL "
-						+ uri + " with base URL " + _agent._baseURL);
+						+ uri + " with base URL " + _agent.getBaseURL());
 			}
 
 			return ret;
 		}
+
+		@Override
+		public void setBaseURL(String uri) {
+			this._baseURI = uri;
+		}
+
+		@Override
+		public String getBaseURL() {
+			return this._baseURI;
+		}
 	}
 
     /**
      * Returns the current baseUrl for this class.
      */
     @Override
     public String getBaseURL() {
-        return _baseURL;
+        return _resolver.getBaseURL();
     }
 
     @Override

openhtmltopdf-pdfbox/src/main/java/com/openhtmltopdf/pdfboxout/PdfBoxRenderer.java

@@ -58,6 +58,8 @@
 import com.openhtmltopdf.bidi.SimpleBidiReorderer;
 import com.openhtmltopdf.context.StyleReference;
 import com.openhtmltopdf.css.style.CalculatedStyle;
+import com.openhtmltopdf.extend.FSCache;
+import com.openhtmltopdf.extend.FSUriResolver;
 import com.openhtmltopdf.extend.HttpStreamFactory;
 import com.openhtmltopdf.extend.NamespaceHandler;
 import com.openhtmltopdf.extend.UserInterface;
@@ -101,10 +103,10 @@ public class PdfBoxRenderer {
     private OutputStream _os;
 
     public PdfBoxRenderer(boolean testMode) {
-        this(DEFAULT_DOTS_PER_POINT, DEFAULT_DOTS_PER_PIXEL, true, testMode, null);
+        this(DEFAULT_DOTS_PER_POINT, DEFAULT_DOTS_PER_PIXEL, true, testMode, null, null, null);
     }
 
-    public PdfBoxRenderer(float dotsPerPoint, int dotsPerPixel, boolean useSubsets, boolean testMode, HttpStreamFactory factory) {
+    public PdfBoxRenderer(float dotsPerPoint, int dotsPerPixel, boolean useSubsets, boolean testMode, HttpStreamFactory factory, FSUriResolver _resolver, FSCache _cache) {
         _pdfDoc = new PDDocument();
 
         _dotsPerPoint = dotsPerPoint;
@@ -113,10 +115,18 @@ public PdfBoxRenderer(float dotsPerPoint, int dotsPerPixel, boolean useSubsets,
         _outputDevice.setWriter(_pdfDoc);
 
         PdfBoxUserAgent userAgent = new PdfBoxUserAgent(_outputDevice);
+
         if (factory != null) {
             userAgent.setHttpStreamFactory(factory);
         }
 
+        if (_resolver != null) {
+            userAgent.setUriResolver(_resolver);
+        }
+
+        if (_cache != null) {
+            userAgent.setExternalCache(_cache);
+        }
 
         _sharedContext = new SharedContext();
         _sharedContext.setUserAgentCallback(userAgent);
@@ -141,8 +151,8 @@ public PdfBoxRenderer(boolean textDirection, boolean testMode,
             boolean useSubsets, HttpStreamFactory httpStreamFactory,
             BidiSplitterFactory splitterFactory, BidiReorderer reorderer, String html,
             Document document, String baseUri, String uri, File file,
-            OutputStream os) {
-        this(DEFAULT_DOTS_PER_POINT, DEFAULT_DOTS_PER_PIXEL, useSubsets, testMode, httpStreamFactory);
+            OutputStream os, FSUriResolver _resolver, FSCache _cache) {
+        this(DEFAULT_DOTS_PER_POINT, DEFAULT_DOTS_PER_PIXEL, useSubsets, testMode, httpStreamFactory, _resolver, _cache);
 
         if (splitterFactory != null) {
             this.setBidiSplitter(splitterFactory);

openhtmltopdf-pdfbox/src/main/java/com/openhtmltopdf/pdfboxout/PdfBoxUserAgent.java

@@ -26,7 +26,6 @@
 import java.net.URI;
 import java.util.Locale;
 
-import com.openhtmltopdf.extend.FSImage;
 import com.openhtmltopdf.layout.SharedContext;
 import com.openhtmltopdf.resource.ImageResource;
 import com.openhtmltopdf.swing.FSCacheKey;
@@ -35,8 +34,6 @@
 import com.openhtmltopdf.util.XRLog;
 
 public class PdfBoxUserAgent extends NaiveUserAgent {
-    private static final int IMAGE_CACHE_CAPACITY = 32;
-
     private SharedContext _sharedContext;
 
     private final PdfBoxOutputDevice _outputDevice;

openhtmltopdf-pdfbox/src/main/java/com/openhtmltopdf/pdfboxout/PdfRendererBuilder.java

@@ -7,6 +7,8 @@
 
 import com.openhtmltopdf.bidi.BidiReorderer;
 import com.openhtmltopdf.bidi.BidiSplitterFactory;
+import com.openhtmltopdf.extend.FSCache;
+import com.openhtmltopdf.extend.FSUriResolver;
 import com.openhtmltopdf.extend.HttpStreamFactory;
 import com.openhtmltopdf.swing.NaiveUserAgent;
 
@@ -26,6 +28,8 @@ public static enum TextDirection { RTL, LTR; }
     private String _uri;
     private File _file;
     private OutputStream _os;
+    private FSUriResolver _resolver;
+    private FSCache _cache;
 
     /**
      * Run the XHTML/XML to PDF conversion and output to an output stream set by toStream.
@@ -42,7 +46,7 @@ public void run() throws Exception {
      * @return
      */
     public PdfBoxRenderer buildPdfRenderer() {
-        return new PdfBoxRenderer(_textDirection, _testMode, _useSubsets, _httpStreamFactory, _splitter, _reorderer, _html, _document, _baseUri, _uri, _file, _os);
+        return new PdfBoxRenderer(_textDirection, _testMode, _useSubsets, _httpStreamFactory, _splitter, _reorderer, _html, _document, _baseUri, _uri, _file, _os, _resolver, _cache);
     }
 
     /**
@@ -86,6 +90,27 @@ public PdfRendererBuilder useHttpStreamImplementation(HttpStreamFactory factory)
         return this;
     }
 
+    /**
+     * Provides a uri resolver to resolve relative uris or private uri schemes.
+     * @param resolver
+     * @return
+     */
+    public PdfRendererBuilder useUriResolver(FSUriResolver resolver) {
+        this._resolver = resolver;
+        return this;
+    }
+
+    /**
+     * Provides an external cache which can choose to cache items between runs,
+     * such as fonts or logo images.
+     * @param cache
+     * @return
+     */
+    public PdfRendererBuilder useCache(FSCache cache) {
+        this._cache = cache;
+        return this;
+    }
+
     /**
      * Provides a text splitter to split text into directional runs. Does nothing by default.
      * @param splitter