Merge pull request #30 from hartig/ClosableFragments

Makes fragments closable

Author: mielvds

src/org/linkeddatafragments/fragments/ILinkedDataFragment.java

@@ -1,13 +1,15 @@
 package org.linkeddatafragments.fragments;
 
+import java.io.Closeable;
+
 import com.hp.hpl.jena.rdf.model.StmtIterator;
 
 /**
  * Represents any possible Linked Data Fragment.
  *
  * @author <a href="http://olafhartig.de">Olaf Hartig</a>
  */
-public interface ILinkedDataFragment
+public interface ILinkedDataFragment extends Closeable
 {
     /**
      * Returns an iterator over the RDF data of this fragment (possibly only

src/org/linkeddatafragments/fragments/LinkedDataFragmentBase.java

@@ -34,6 +34,14 @@ protected LinkedDataFragmentBase( final String fragmentURL,
         this.isLastPage = isLastPage;
     }
 
+    /**
+     * Does nothing. May be overridden by subclasses that hold some objects
+     * that need to be closed (such as iterators from the underlying data
+     * source).
+     */
+    @Override
+    public void close() {}
+
     @Override
     public boolean isPageOnly() {
         return true;

src/org/linkeddatafragments/servlet/LinkedDataFragmentServlet.java

@@ -138,16 +138,16 @@ private IDataSource getDataSource(HttpServletRequest request) throws DataSourceN
 
     @Override
     public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException {
+        ILinkedDataFragment fragment = null;
         try {
             final IDataSource dataSource = getDataSource( request );
 
             final ILinkedDataFragmentRequest ldfRequest =
                     dataSource.getRequestParser()
                               .parseIntoFragmentRequest( request, config );
 
-            final ILinkedDataFragment fragment =
-                    dataSource.getRequestProcessor()
-                              .createRequestedFragment( ldfRequest );
+            fragment = dataSource.getRequestProcessor()
+                                 .createRequestedFragment( ldfRequest );
 
             final Model output = ModelFactory.createDefaultModel();
             output.setNsPrefixes(config.getPrefixes());
@@ -176,6 +176,17 @@ public void doGet(HttpServletRequest request, HttpServletResponse response) thro
                 throw new ServletException(ex1);
             }
         }
+        finally {
+            // close the fragment
+            if ( fragment != null ) {
+                try {
+                    fragment.close();
+                }
+                catch ( Exception e ) {
+                    // ignore
+                }
+            }
+        }
     }
 
 }