Complete initial Tika-ification of the metadata extractor

The remaining extractors to be converted to Tika now have been, tests have
 been included for the image metadata extraction, and some extension points
 for future extractors have been created.


git-svn-id: https://svn.alfresco.com/repos/alfresco-enterprise/alfresco/HEAD/root@20669 c4b6b30b-aa2e-2d43-bbcb-ca4b014f7261

source/java/org/alfresco/repo/content/metadata/TikaPoweredMetadataExtracter.java

@@ -26,6 +26,7 @@ import java.text.ParseException;
 import java.text.SimpleDateFormat;
 import java.util.ArrayList;
 import java.util.Date;
+import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Locale;
 import java.util.Map;
@@ -35,11 +36,17 @@ import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.tika.metadata.Metadata;
 import org.apache.tika.mime.MediaType;
-import org.apache.tika.parser.AutoDetectParser;
 import org.apache.tika.parser.ParseContext;
 import org.apache.tika.parser.Parser;
-import org.apache.tika.sax.BodyContentHandler;
+import org.apache.tika.sax.ContentHandlerDecorator;
+import org.apache.tika.sax.XHTMLContentHandler;
+import org.apache.tika.sax.xpath.Matcher;
+import org.apache.tika.sax.xpath.MatchingContentHandler;
+import org.apache.tika.sax.xpath.XPathParser;
+import org.xml.sax.Attributes;
 import org.xml.sax.ContentHandler;
+import org.xml.sax.Locator;
+import org.xml.sax.SAXException;
 
 /**
  * The parent of all Metadata Extractors which use
@@ -145,11 +152,20 @@ public abstract class TikaPoweredMetadataExtracter extends AbstractMappingMetada
      */
     protected abstract Parser getParser();
     
+    /**
+     * Do we care about the contents of the
+     *  extracted header, or nothing at all?
+     */
+    protected boolean needHeaderContents() {
+       return false;
+    }
+    
     /**
      * Allows implementation specific mappings
      *  to be done.
      */
-    protected Map<String, Serializable> extractSpecific(Metadata metadata, Map<String, Serializable> properties) {
+    protected Map<String, Serializable> extractSpecific(Metadata metadata, 
+          Map<String, Serializable> properties, Map<String,String> headers) {
        return properties;
     }
     
@@ -163,9 +179,19 @@ public abstract class TikaPoweredMetadataExtracter extends AbstractMappingMetada
         {
             is = reader.getContentInputStream();
             Parser parser = getParser();
-            ContentHandler handler = new BodyContentHandler() ;
             Metadata metadata = new Metadata();
             ParseContext context = new ParseContext();
+            
+            ContentHandler handler;
+            Map<String,String> headers = null;
+            if(needHeaderContents()) {
+               MapCaptureContentHandler headerCapture = 
+                  new MapCaptureContentHandler();
+               headers = headerCapture.tags;
+               handler = new HeadContentHandler(headerCapture);
+            } else {
+               handler = new NullContentHandler(); 
+            }
 
             parser.parse(is, handler, metadata, context);
             
@@ -213,7 +239,7 @@ public abstract class TikaPoweredMetadataExtracter extends AbstractMappingMetada
             //  instance to map the Tika keys onto its 
             //  existing namespace so that older properties
             //  files continue to map correctly
-            rawProperties = extractSpecific(metadata, rawProperties);
+            rawProperties = extractSpecific(metadata, rawProperties, headers);
         }
         finally
         {
@@ -225,4 +251,123 @@ public abstract class TikaPoweredMetadataExtracter extends AbstractMappingMetada
 
         return rawProperties;
     }
+    
+    /**
+     * This content handler will capture entries from within
+     *  the header of the Tika content XHTML, but ignore the
+     *  rest.
+     */
+    protected static class HeadContentHandler extends ContentHandlerDecorator {
+       /**
+        * XHTML XPath parser.
+        */
+       private static final XPathParser PARSER =
+           new XPathParser("xhtml", XHTMLContentHandler.XHTML);
+
+       /**
+        * The XPath matcher used to select the XHTML body contents.
+        */
+       private static final Matcher MATCHER =
+           PARSER.parse("/xhtml:html/xhtml:head/descendant:node()");
+
+       /**
+        * Creates a content handler that passes all XHTML body events to the
+        * given underlying content handler.
+        *
+        * @param handler content handler
+        */
+       protected HeadContentHandler(ContentHandler handler) {
+           super(new MatchingContentHandler(handler, MATCHER));
+       }
+    }
+    /**
+     * This content handler will grab all tags and attributes,
+     *  and record the textual content of the last seen one
+     *  of them.
+     * Normally only used with {@link HeadContentHandler} 
+     */
+    protected static class MapCaptureContentHandler implements ContentHandler {
+       protected Map<String,String> tags =
+          new HashMap<String, String>();
+       private StringBuffer text;
+
+      @Override
+      public void characters(char[] ch, int start, int len) {
+         if(text != null) {
+            text.append(ch, start, len);
+         }
+      }
+      @Override
+      public void endElement(String namespace, String localname,
+            String qname) {
+         if(text != null && text.length() > 0) {
+            tags.put(qname, text.toString());
+         }
+         text = null;
+      }
+      @Override
+      public void startElement(String namespace, String localname,
+            String qname, Attributes attrs) {
+         for(int i=0; i<attrs.getLength(); i++) {
+            tags.put(attrs.getQName(i), attrs.getValue(i));
+         }
+         text = new StringBuffer();
+      }
+      
+      @Override
+      public void endDocument() throws SAXException {}
+      @Override
+      public void endPrefixMapping(String paramString) throws SAXException {}
+      @Override
+      public void ignorableWhitespace(char[] paramArrayOfChar, int paramInt1,
+            int paramInt2) throws SAXException {}
+      @Override
+      public void processingInstruction(String paramString1, String paramString2)
+            throws SAXException {}
+      @Override
+      public void setDocumentLocator(Locator paramLocator) {}
+      @Override
+      public void skippedEntity(String paramString) throws SAXException {}
+      @Override
+      public void startDocument() throws SAXException {}
+      @Override
+      public void startPrefixMapping(String paramString1, String paramString2)
+            throws SAXException {}
+    }
+    /**
+     * A content handler that ignores all the content it finds.
+     * Normally used when we only want the metadata, and don't
+     *  care about the file contents.
+     */
+    protected static class NullContentHandler implements ContentHandler {
+      @Override
+      public void characters(char[] paramArrayOfChar, int paramInt1,
+            int paramInt2) throws SAXException {}
+      @Override
+      public void endDocument() throws SAXException {}
+      @Override
+      public void endElement(String paramString1, String paramString2,
+            String paramString3) throws SAXException {}
+      @Override
+      public void endPrefixMapping(String paramString) throws SAXException {}
+      @Override
+      public void ignorableWhitespace(char[] paramArrayOfChar, int paramInt1,
+            int paramInt2) throws SAXException {}
+      @Override
+      public void processingInstruction(String paramString1, String paramString2)
+            throws SAXException {}
+      @Override
+      public void setDocumentLocator(Locator paramLocator) {}
+      @Override
+      public void skippedEntity(String paramString) throws SAXException {}
+      @Override
+      public void startDocument() throws SAXException {}
+      @Override
+      public void startElement(String paramString1, String paramString2,
+            String paramString3, Attributes paramAttributes)
+            throws SAXException {}
+      @Override
+      public void startPrefixMapping(String paramString1, String paramString2)
+            throws SAXException {}
+    }
 }