code: /*
   * Copyright 2012-2018 Chronicle Map Contributors
   *
   * Licensed 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 net.openhft.chronicle.map;
  
  import com.thoughtworks.xstream.XStream;
  import com.thoughtworks.xstream.converters.Converter;
  import com.thoughtworks.xstream.io.json.JettisonMappedXmlDriver;
  import net.openhft.chronicle.core.Jvm;
  import net.openhft.xstream.converters.*;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import java.io.*;
  import java.util.List;
  import java.util.Map;
  import java.util.zip.GZIPInputStream;
  import java.util.zip.GZIPOutputStream;
  
  /**
   * @author Rob Austin.
   */
  final class JsonSerializer {
      private JsonSerializer() {
      }
  
      static final String LOG_ERROR_SUGGEST_X_STREAM =
              "map.getAll(<file>) and map.putAll(<file>) methods require the JSON XStream serializer, " +
                      "we don't include these artifacts by default as some users don't require this functionality. " +
                      "Please add the following artifacts to your project\n" +
                      "<dependency>\n" +
                      " <groupId>xstream</groupId>\n" +
                      " <artifactId>xstream</artifactId>\n" +
                      " <version>1.2.2</version>\n" +
                      "</dependency>\n" +
                      "<dependency>\n" +
                      " <groupId>org.codehaus.jettison</groupId>\n" +
                      " <artifactId>jettison</artifactId>\n" +
                      " <version>1.3.6</version>\n" +
                      "</dependency>\n";
  
      static synchronized <K, V> void getAll(final File toFile,
                                             final Map<K, V> map,
                                             final List<?> jsonConverters) throws IOException {
          final XStream xstream = xStream(map, jsonConverters);
  
          try (OutputStream outputStream = createOutputStream(toFile)) {
              xstream.toXML(map, outputStream);
          }
      }
  
      static synchronized <K, V> void putAll(final File fromFile,
                                             final Map<K, V> map,
                                             final List<?> jsonConverters) throws IOException {
          final XStream xstream = xStream(map, jsonConverters);
  
          try (InputStream inputStream = createInputStream(fromFile)) {
              xstream.fromXML(inputStream);
          }
      }
  
      private static InputStream createInputStream(final File toFile) throws IOException {
          if (toFile.getName().toLowerCase().endsWith(".gz"))
              return new GZIPInputStream(new FileInputStream(toFile));
          else
              return new FileInputStream(toFile);
      }
  
      private static OutputStream createOutputStream(final File toFile) throws IOException {
          if (toFile.getName().toLowerCase().endsWith(".gz"))
              return new GZIPOutputStream(new FileOutputStream(toFile));
          else
              return new FileOutputStream(toFile);
      }
  
      private static <K, V> XStream xStream(final Map<K, V> map, final List<?> jsonConverters) {
          try {
              final XStream xstream = new XStream(new JettisonMappedXmlDriver());
              xstream.setMode(XStream.NO_REFERENCES);
              xstream.alias("cmap", map.getClass());
  
              registerChronicleMapConverter(map, xstream);
              xstream.registerConverter(new ByteBufferConverter());
              xstream.registerConverter(new ValueConverter());
              xstream.registerConverter(new StringBuilderConverter());
              xstream.registerConverter(new CharSequenceConverter());
  
              for (Object c : jsonConverters) {
                  if (c instanceof Converter) {
                      xstream.registerConverter((Converter) c);
                  } else {
                      Jvm.warn().on(JsonSerializer.class,
                              "Skipping Converter of type class=" + c.getClass().getName() + " as " +
                                      " expecting an object of type com.thoughtworks.xstream.converters" +
                                      ".Converter");
                  }
              }
  
              return xstream;
          } catch (NoClassDefFoundError e) {
              throw new RuntimeException(LOG_ERROR_SUGGEST_X_STREAM, e);
          }
      }
  
      private static <K, V> void registerChronicleMapConverter(final Map<K, V> map, final XStream xstream) {
          xstream.registerConverter(new VanillaChronicleMapConverter<>(map));
      }
  }