TILES-538 - Pluggable debugging around rendering
git-svn-id: https://svn.apache.org/repos/asf/tiles/framework/trunk@1199201 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/tiles-request/tiles-request-api/src/main/java/org/apache/tiles/request/render/PublisherRenderer.java b/tiles-request/tiles-request-api/src/main/java/org/apache/tiles/request/render/PublisherRenderer.java
new file mode 100644
index 0000000..5ef0f87
--- /dev/null
+++ b/tiles-request/tiles-request-api/src/main/java/org/apache/tiles/request/render/PublisherRenderer.java
@@ -0,0 +1,102 @@
+/*
+ * $Id$
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.tiles.request.render;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+import org.apache.tiles.request.Request;
+
+/**
+ * Provides a Publisher-Subscriber implementation around the provided renderer to delegate to.
+ *
+ * @version $Rev: 1035784 $ $Date: 2010-11-16 20:24:12 +0000 (Tue, 16 Nov 2010) $
+ * @since 3.0.0
+ */
+public class PublisherRenderer implements TypeDetectingRenderer {
+
+ public interface RendererListener{
+ /** Called before the delegate's render method is called. */
+ void start(String template, Request request) throws IOException;
+ /** Called after the delegate's render method is called. */
+ void end(String template, Request request) throws IOException;
+ /** If the delegate render method throws an IOException it is passed through this. */
+ void handleIOException(IOException ex, Request request) throws IOException;
+ }
+
+ private final TypeDetectingRenderer renderer;
+ private final List<RendererListener> listeners = new ArrayList<RendererListener>();
+ private final List<RendererListener> listenersReversed = new ArrayList<RendererListener>();
+
+ public PublisherRenderer(TypeDetectingRenderer renderer){
+ this.renderer = renderer;
+ }
+
+ @Override
+ public void render(String path, Request request) throws IOException {
+ if (path == null) {
+ throw new CannotRenderException("Cannot dispatch a null path");
+ }
+ try{
+ for(RendererListener listener : listeners){
+ listener.start(path, request);
+ }
+ renderer.render(path, request);
+ }catch(IOException ex){
+ handleIOException(ex, request);
+ }finally{
+ for(RendererListener wrapper : listenersReversed){
+ wrapper.end(path, request);
+ }
+ }
+ }
+
+ @Override
+ public boolean isRenderable(String path, Request request) {
+ return renderer.isRenderable(path, request);
+ }
+
+ public void addListener(RendererListener listener){
+ listeners.add(listener);
+ listenersReversed.clear();
+ listenersReversed.addAll(listeners);
+ Collections.reverse(listenersReversed);
+ }
+
+ private void handleIOException(IOException exception, Request request) throws IOException{
+ IOException ex = exception;
+ boolean throwIt = listeners.isEmpty();
+ for(RendererListener listener : listenersReversed){
+ try{
+ listener.handleIOException(ex, request);
+ throwIt = false;
+ }catch(IOException newEx){
+ ex = newEx;
+ throwIt = true;
+ }
+ }
+ if(throwIt){
+ throw ex;
+ }
+ }
+}
