Merge pull request #2 from ThomasDaheim/Extend-GPXParser

Fixed extension handling

src/com/hs/gpxparser/GPXParser.java

@@ -1,5 +1,6 @@
 package com.hs.gpxparser;
 
+import com.hs.gpxparser.extension.DummyExtensionParser;
 import java.io.InputStream;
 import java.text.ParseException;
 import java.util.Date;
@@ -63,6 +64,11 @@ public class GPXParser extends BaseGPX {
 	 * @throws Exception
 	 */
 	public GPX parseGPX(InputStream in) throws Exception {
+                // TFE, 20180217: add default parser if none set
+                if (this.extensionParsers.isEmpty()) {
+                    this.extensionParsers.add(new DummyExtensionParser());
+                }
+
 		DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
 		Document doc = builder.parse(in);
 		Node firstChild = doc.getFirstChild();

src/com/hs/gpxparser/GPXWriter.java

@@ -1,5 +1,6 @@
 package com.hs.gpxparser;
 
+import com.hs.gpxparser.extension.DummyExtensionParser;
 import java.io.OutputStream;
 import java.util.Iterator;
 
@@ -33,7 +34,12 @@
 public class GPXWriter extends BaseGPX {
 
 	public void writeGPX(GPX gpx, OutputStream out) throws ParserConfigurationException, TransformerException {
-		DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
+                // TFE, 20180217: add default parser if none set
+                if (this.extensionParsers.isEmpty()) {
+                    this.extensionParsers.add(new DummyExtensionParser());
+                }
+
+                DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder();
 		Document doc = builder.newDocument();
 		Node gpxNode = doc.createElement(GPXConstants.NODE_GPX);
 
@@ -459,7 +465,7 @@ private void addExtensionToNode(Extension e, Node n, Document doc) {
 		if (e.getExtensionsParsed() > 0) {
 			Node node = doc.createElement(GPXConstants.NODE_EXTENSIONS);
 			for (IExtensionParser parser : this.extensionParsers) {
-				parser.writeExtensions(node, doc);
+				parser.writeExtensions(e, node, doc);
 			}
 			n.appendChild(node);
 		}

src/com/hs/gpxparser/extension/DummyExtensionHolder.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2014ff Thomas Feuster
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package com.hs.gpxparser.extension;
+
+import org.w3c.dom.NodeList;
+
+/**
+ * Simple holder for node elements under <extensions>.
+ * 
+ * Is used by the default DummyExtensionParser in case no other
+ * IExtensionParser are set. Otherwise the extensions would get lost 
+ * when simply parsing and writing a gpx file.
+ * 
+ * @author thomas
+ */
+public class DummyExtensionHolder {
+    private NodeList myNodeList;
+
+    DummyExtensionHolder() {
+    }
+
+    DummyExtensionHolder(final NodeList childNodes) {
+        myNodeList = childNodes;
+    }
+
+    public NodeList getNodeList() {
+        return myNodeList;
+    }
+
+    public void setNodeList(final NodeList nodeList) {
+        myNodeList = nodeList;
+    }
+}

src/com/hs/gpxparser/extension/DummyExtensionParser.java

@@ -1,23 +1,40 @@
 package com.hs.gpxparser.extension;
 
+import com.hs.gpxparser.GPXConstants;
+import com.hs.gpxparser.modal.Extension;
 import org.w3c.dom.Document;
 import org.w3c.dom.Node;
+import org.w3c.dom.NodeList;
 
 public class DummyExtensionParser implements IExtensionParser {
+    @Override
+    public String getId() {
+            return "Basic Extension Parser";
+    }
 
-	@Override
-	public String getId() {
-		return "Basic Extension Parser";
-	}
+    @Override
+    public Object parseExtensions(Node node) {
+        // store all nodes under extension in DummyExtensionHolder - if any
+        if (GPXConstants.NODE_EXTENSIONS.equals(node.getNodeName()) && (node.getChildNodes().getLength() > 0)) {
+            return new DummyExtensionHolder(node.getChildNodes());
+        } else {
+            return null;
+        }
+    }
 
-	@Override
-	public Object parseExtensions(Node node) {
-		// TODO get your object from the node
-		return null;
-	}
-
-	@Override
-	public void writeExtensions(Node node, Document doc) {
-		// TODO write your object to node
-	}
+    @Override
+    public void writeExtensions(Extension e, Node node, Document doc) {
+        if(e.getExtensionData(getId()) != null) {
+            // add all nodes from DummyExtensionHolder to the document
+            final DummyExtensionHolder holder = (DummyExtensionHolder) e.getExtensionData(getId());
+            final NodeList nodes = holder.getNodeList();
+
+            // https://stackoverflow.com/questions/5786936/create-xml-document-using-nodelist
+            for (int i = 0; i < nodes.getLength(); i++) {
+                final Node extNode = nodes.item(i);
+                final Node copyNode = doc.importNode(extNode, true);
+                node.appendChild(copyNode);
+            }
+        }
+    }
 }

src/com/hs/gpxparser/extension/IExtensionParser.java

@@ -1,5 +1,6 @@
 package com.hs.gpxparser.extension;
 
+import com.hs.gpxparser.modal.Extension;
 import org.w3c.dom.Document;
 import org.w3c.dom.Node;
 
@@ -9,6 +10,7 @@ public interface IExtensionParser {
 
 	public Object parseExtensions(Node node);
 
-	public void writeExtensions(Node node, Document doc);
+        // TFE, 20180216: can't write any data out if the node hasn't been passed as well!
+	public void writeExtensions(Extension e, Node node, Document doc);
 
 }

src/com/hs/gpxparser/modal/Extension.java

@@ -36,8 +36,14 @@ public void setExtensionData(HashMap<String, Object> extensionData) {
 	 * 				the extension parser's job to set it properly.
 	 */
 	public void addExtensionData(String parserId, Object data) {
+                // TFE, 20180217
+                // don't add null data - otherwise for each parser one null entry would be added
+                // to each extension in a gpx file! That is too much waste considering
+                // that in most cases no extensions at all are present
+                if (data == null) return;
+
 		if(extensionData == null) {
-			extensionData = new HashMap<String, Object>();
+			extensionData = new HashMap<>();
 		}
 		extensionData.put(parserId, data);
 	}