Add XMP Exporter

src/main/java/org/jabref/logic/exporter/ExporterFactory.java

@@ -54,6 +54,7 @@ public static ExporterFactory create(Map<String, TemplateExporter> customFormats
         exporters.add(new OpenDocumentSpreadsheetCreator());
         exporters.add(new MSBibExporter());
         exporters.add(new ModsExporter());
+        exporters.add(new XmpExporter());
 
         // Now add custom export formats
         exporters.addAll(customFormats.values());

src/main/java/org/jabref/logic/exporter/XmpExporter.java

@@ -0,0 +1,43 @@
+package org.jabref.logic.exporter;
+
+import java.io.BufferedWriter;
+import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.List;
+import java.util.Objects;
+
+import org.jabref.Globals;
+import org.jabref.logic.util.FileType;
+import org.jabref.logic.xmp.XmpUtilWriter;
+import org.jabref.model.database.BibDatabaseContext;
+import org.jabref.model.entry.BibEntry;
+
+/**
+ * A custom exporter to write bib entries to a .xmp file for further processing
+ * in other scenarios and applications. The xmp metadata are written in dublin
+ * core format.
+ */
+public class XmpExporter extends Exporter {
+
+    public XmpExporter() {
+        super("XmpBib", FileType.ENDNOTE_XMP.getDescription(), FileType.ENDNOTE_XMP);
+    }
+
+    @Override
+    public void export(BibDatabaseContext databaseContext, Path file, Charset encoding, List<BibEntry> entries) throws Exception {
+        Objects.requireNonNull(databaseContext);
+        Objects.requireNonNull(entries);
+
+        if (entries.isEmpty()) {
+            return;
+        }
+
+        try (BufferedWriter writer = Files.newBufferedWriter(file, StandardCharsets.UTF_8)) {
+            writer.write(XmpUtilWriter.generateXmpString(entries, Globals.prefs.getXMPPreferences()));
+            writer.flush();
+        }
+    }
+
+}

src/main/java/org/jabref/logic/util/FileType.java

@@ -26,6 +26,7 @@ public enum FileType {
     DIN_1505(Localization.lang("%0 file", "DIN 1505"), "rtf"),
     ENDNOTE(Localization.lang("%0 file", "EndNote/Refer"), "ref", "enw"),
     ENDNOTE_XML(Localization.lang("%0 file", "EndNote XML"), "xml"),
+    ENDNOTE_XMP(Localization.lang("%0 file", "Xmp"), "xmp"),
     ENDNOTE_TXT(Localization.lang("%0 file", "EndNote"), "txt"), //for export
     FREECITE(Localization.lang("%0 file", "FreeCite"), "txt", "xml"),
     HARVARD_RTF(Localization.lang("%0 file", "Harvard"), "rtf"),

src/main/java/org/jabref/logic/xmp/XmpUtilWriter.java

@@ -3,6 +3,8 @@
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
+import java.io.UnsupportedEncodingException;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.ArrayList;
@@ -82,6 +84,16 @@ public static void writeXmp(Path file, BibEntry entry,
         XmpUtilWriter.writeXmp(file, bibEntryList, database, xmpPreferences);
     }
 
+    /**
+     * Writes the information of the bib entry to the dublin core schema using
+     * a custom extractor.
+     *
+     * @param dcSchema  Dublin core schema, which is filled with the bib entry.
+     * @param entry     The entry, which is added to the dublin core metadata.
+     * @param database  maybenull An optional database which the given bibtex entries belong to, which will be used to
+     *                  resolve strings. If the database is null the strings will not be resolved.
+     * @param xmpPreferences    The user's xmp preferences.
+     */
     private static void writeToDCSchema(DublinCoreSchema dcSchema, BibEntry entry, BibDatabase database,
             XmpPreferences xmpPreferences) {
 
@@ -91,7 +103,6 @@ private static void writeToDCSchema(DublinCoreSchema dcSchema, BibEntry entry, B
         dcExtractor.fillDublinCoreSchema();
     }
 
-
     /**
      * Try to write the given BibTexEntry as a DublinCore XMP Schema
      *
@@ -159,6 +170,38 @@ private static void writeDublinCore(PDDocument document,
         catalog.setMetadata(metadataStream);
     }
 
+    /**
+     * This method generates an xmp metadata string in dublin core format.
+     * <br/>
+     *
+     * @param entries   A list of entries, which are added to the dublin core metadata.
+     * @param xmpPreferences    The user's xmp preferences.
+     *
+     * @return  If something goes wrong (e.g. an exception is thrown), the method returns an empty string,
+     *          otherwise it returns the xmp metadata as a string in dublin core format.
+     */
+    public static String generateXmpString(List<BibEntry> entries, XmpPreferences xmpPreferences) {
+        XMPMetadata meta = XMPMetadata.createXMPMetadata();
+        for (BibEntry entry : entries) {
+            DublinCoreSchema dcSchema = meta.createAndAddDublinCoreSchema();
+            XmpUtilWriter.writeToDCSchema(dcSchema, entry, null, xmpPreferences);
+        }
+        try (ByteArrayOutputStream os = new ByteArrayOutputStream()) {
+            XmpSerializer serializer = new XmpSerializer();
+            serializer.serialize(meta, os, true);
+            return os.toString(StandardCharsets.UTF_8.name());
+        } catch (TransformerException e) {
+            LOGGER.warn("Tranformation into xmp not possible: " + e.getMessage());
+            return "";
+        } catch (UnsupportedEncodingException e) {
+            LOGGER.warn("Unsupported encoding to UTF-8 of bib entries in xmp metadata.");
+            return "";
+        } catch (IOException e) {
+            LOGGER.warn("IO Exception thrown by closing the output stream.");
+            return "";
+        }
+    }
+
     /**
      * Try to write the given BibTexEntry in the Document Information (the
      * properties of the pdf).