Add tool for generating JSON from DDF list file

Signed-off-by: Ville Skyttä <ville.skytta@iki.fi>

leshan-core/src/main/java/org/eclipse/leshan/core/model/Ddf2JsonGenerator.java

@@ -37,6 +37,9 @@ public class Ddf2JsonGenerator {
 
     private Gson gson;
 
+    static final String DEFAULT_DDF_FILES_PATH = "ddffiles";
+    static final String DEFAULT_OUTPUT_PATH = "src/main/resources/objectspec.json";
+
     public Ddf2JsonGenerator() {
         GsonBuilder gsonBuilder = new GsonBuilder();
         gsonBuilder.registerTypeAdapter(ObjectModel.class, new ObjectModelSerializer());
@@ -51,7 +54,7 @@ private void generate(Collection<ObjectModel> objectModels, OutputStream output)
         }
     }
 
-    private void generate(File input, OutputStream output) throws IOException {
+    public void generate(File input, OutputStream output) throws IOException {
         // check input exists
         if (!input.exists())
             throw new FileNotFoundException(input.toString());
@@ -90,8 +93,8 @@ public int compare(ObjectModel o1, ObjectModel o2) {
 
     public static void main(String[] args) throws FileNotFoundException, IOException {
         // default value
-        String ddfFilesPath = "ddffiles";
-        String outputPath = "src/main/resources/objectspec.json";
+        String ddfFilesPath = DEFAULT_DDF_FILES_PATH;
+        String outputPath = DEFAULT_OUTPUT_PATH;
 
         // use arguments if they exit
         if (args.length >= 1)

leshan-core/src/main/java/org/eclipse/leshan/core/model/DdfList2JsonGenerator.java

@@ -0,0 +1,125 @@
+/*******************************************************************************
+ * Copyright (c) 2013-2017 Sierra Wireless and others.
+ *
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * and Eclipse Distribution License v1.0 which accompany this distribution.
+ *
+ * The Eclipse Public License is available at
+ *    http://www.eclipse.org/legal/epl-v10.html
+ * and the Eclipse Distribution License is available at
+ *    http://www.eclipse.org/org/documents/edl-v10.html.
+ *
+ * Contributors:
+ *     Ville Skyttä - initial implementation
+ *******************************************************************************/
+package org.eclipse.leshan.core.model;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.net.URLConnection;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.List;
+
+import javax.xml.parsers.DocumentBuilder;
+import javax.xml.parsers.DocumentBuilderFactory;
+import javax.xml.parsers.ParserConfigurationException;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.w3c.dom.Document;
+import org.w3c.dom.Element;
+import org.w3c.dom.Node;
+import org.w3c.dom.NodeList;
+import org.xml.sax.SAXException;
+
+public class DdfList2JsonGenerator {
+
+    private static final Logger LOG = LoggerFactory.getLogger(DdfList2JsonGenerator.class);
+
+    private final DocumentBuilderFactory factory;
+
+    public DdfList2JsonGenerator() {
+        factory = DocumentBuilderFactory.newInstance();
+    }
+
+    private void processDdfList(String url, String ddfFilesPath) throws IOException {
+
+        LOG.debug("Processing DDF list file {}", url);
+
+        List<String> ddfUrls = new ArrayList<>();
+
+        try {
+            DocumentBuilder builder = factory.newDocumentBuilder();
+            Document document = builder.parse(url);
+
+            NodeList items = document.getDocumentElement().getElementsByTagName("Item");
+            for (int i = 0; i < items.getLength(); i++) {
+                Node item = items.item(i);
+                Node ddf = ((Element) item).getElementsByTagName("DDF").item(0);
+                ddfUrls.add(ddf.getTextContent());
+            }
+        } catch (SAXException | ParserConfigurationException e) {
+            throw new IOException(e);
+        }
+
+        for (String ddfUrl : ddfUrls) {
+
+            URL parsedUrl;
+            try {
+                parsedUrl = new URL(ddfUrl);
+            } catch (MalformedURLException e) {
+                LOG.error("Skipping malformed URL {}", ddfUrl);
+                continue;
+            }
+
+            String filename = parsedUrl.getPath();
+            filename = filename.substring(filename.lastIndexOf("/"));
+
+            Path outPath = Paths.get(ddfFilesPath, filename);
+
+            LOG.debug("Downloading DDF file {} to {}", ddfUrl, outPath);
+
+            URLConnection conn = parsedUrl.openConnection();
+            // The default Java User-Agent gets 403 Forbidden from OMA website
+            conn.setRequestProperty("User-Agent", "Leshan " + getClass().getSimpleName());
+
+            try (InputStream in = conn.getInputStream()) {
+                Files.copy(in, outPath);
+            }
+        }
+    }
+
+    public static void main(String[] args) throws IOException {
+        // default values
+        String ddfFilesPath = Ddf2JsonGenerator.DEFAULT_DDF_FILES_PATH;
+        String outputPath = Ddf2JsonGenerator.DEFAULT_OUTPUT_PATH;
+        String ddfListUrl = "https://raw.githubusercontent.com/OpenMobileAlliance/openmobilealliance.github.io/master/OMNA/LwM2M/DDF.xml";
+
+        // use arguments if they exist
+        if (args.length >= 1)
+            ddfFilesPath = args[0]; // the path to a DDF file or a folder which contains DDF files.
+        if (args.length >= 2)
+            outputPath = args[1]; // the path of the output file.
+        if (args.length >= 3)
+            ddfListUrl = args[2]; // the path of the DDF list file.
+
+        new DdfList2JsonGenerator().processDdfList(ddfListUrl, ddfFilesPath);
+
+        LOG.error("DDF list {} processed to {}, proceeding with JSON generation in {}", ddfListUrl, ddfFilesPath,
+                outputPath);
+
+        // generate object spec file
+        Ddf2JsonGenerator ddfJsonGenerator = new Ddf2JsonGenerator();
+        try (FileOutputStream fileOutputStream = new FileOutputStream(outputPath)) {
+            ddfJsonGenerator.generate(new File(ddfFilesPath), fileOutputStream);
+        }
+    }
+}