Add XMP Exporter

src/main/java/org/jabref/cli/ArgumentProcessor.java

@@ -41,6 +41,7 @@
 import org.jabref.logic.search.SearchQuery;
 import org.jabref.logic.shared.prefs.SharedDatabasePreferences;
 import org.jabref.logic.util.OS;
+import org.jabref.logic.xmp.XmpPreferences;
 import org.jabref.model.Defaults;
 import org.jabref.model.EntryTypes;
 import org.jabref.model.database.BibDatabase;
@@ -471,7 +472,8 @@ private void importPreferences() {
             LayoutFormatterPreferences layoutPreferences = Globals.prefs
                     .getLayoutFormatterPreferences(Globals.journalAbbreviationLoader);
             SavePreferences savePreferences = SavePreferences.loadForExportFromPreferences(Globals.prefs);
-            Globals.exportFactory = ExporterFactory.create(customExporters, layoutPreferences, savePreferences);
+            XmpPreferences xmpPreferences = Globals.prefs.getXMPPreferences();
+            Globals.exportFactory = ExporterFactory.create(customExporters, layoutPreferences, savePreferences, xmpPreferences);
         } catch (JabRefException ex) {
             LOGGER.error("Cannot import preferences", ex);
         }

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

@@ -11,6 +11,7 @@
 import org.jabref.logic.journals.JournalAbbreviationLoader;
 import org.jabref.logic.layout.LayoutFormatterPreferences;
 import org.jabref.logic.util.FileType;
+import org.jabref.logic.xmp.XmpPreferences;
 import org.jabref.preferences.JabRefPreferences;
 
 public class ExporterFactory {
@@ -29,7 +30,7 @@ private ExporterFactory(List<Exporter> exporters) {
     }
 
     public static ExporterFactory create(Map<String, TemplateExporter> customFormats,
-            LayoutFormatterPreferences layoutPreferences, SavePreferences savePreferences) {
+            LayoutFormatterPreferences layoutPreferences, SavePreferences savePreferences, XmpPreferences xmpPreferences) {
 
         List<Exporter> exporters = new ArrayList<>();
 
@@ -54,6 +55,7 @@ public static ExporterFactory create(Map<String, TemplateExporter> customFormats
         exporters.add(new OpenDocumentSpreadsheetCreator());
         exporters.add(new MSBibExporter());
         exporters.add(new ModsExporter());
+        exporters.add(new XmpExporter(xmpPreferences));
 
         // Now add custom export formats
         exporters.addAll(customFormats.values());
@@ -65,7 +67,8 @@ public static ExporterFactory create(JabRefPreferences preferences, JournalAbbre
         Map<String, TemplateExporter> customFormats = preferences.customExports.getCustomExportFormats(preferences, abbreviationLoader);
         LayoutFormatterPreferences layoutPreferences = preferences.getLayoutFormatterPreferences(abbreviationLoader);
         SavePreferences savePreferences = SavePreferences.loadForExportFromPreferences(preferences);
-        return create(customFormats, layoutPreferences, savePreferences);
+        XmpPreferences xmpPreferences = preferences.getXMPPreferences();
+        return create(customFormats, layoutPreferences, savePreferences, xmpPreferences);
     }
 
     /**

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

@@ -0,0 +1,72 @@
+package org.jabref.logic.exporter;
+
+import java.io.BufferedWriter;
+import java.io.IOException;
+import java.nio.charset.Charset;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Objects;
+
+import org.jabref.logic.util.FileType;
+import org.jabref.logic.xmp.XmpPreferences;
+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 {
+
+    private static final String XMP_SPLIT_PATTERN = "split";
+
+    private final XmpPreferences xmpPreferences;
+
+    public XmpExporter(XmpPreferences xmpPreferences) {
+        super("xmp", FileType.PLAIN_XMP.getDescription(), FileType.PLAIN_XMP);
+        this.xmpPreferences = xmpPreferences;
+    }
+
+    @Override
+    public void export(BibDatabaseContext databaseContext, Path file, Charset encoding, List<BibEntry> entries) throws Exception {
+        Objects.requireNonNull(databaseContext);
+        Objects.requireNonNull(file);
+        Objects.requireNonNull(entries);
+
+        if (entries.isEmpty()) {
+            return;
+        }
+
+        // This is a distinction between writing all entries from the supplied list to a single .xmp file,
+        // or write every entry to a separate file.
+        if (file.getFileName().toString().trim().equals(XMP_SPLIT_PATTERN)) {
+
+            for (BibEntry entry : entries) {
+                // Avoid situations, where two cite keys are null
+                Path entryFile;
+                String suffix = entry.getId() + "_" + entry.getCiteKey() + ".xmp";
+                if (file.getParent() == null) {
+                    entryFile = Paths.get(suffix);
+                } else {
+                    entryFile = Paths.get(file.getParent().toString() + "/" + suffix);
+                }
+
+                this.writeBibToXmp(entryFile, Arrays.asList(entry), encoding);
+            }
+        } else {
+            this.writeBibToXmp(file, entries, encoding);
+        }
+    }
+
+    private void writeBibToXmp(Path file, List<BibEntry> entries, Charset encoding) throws IOException {
+        try (BufferedWriter writer = Files.newBufferedWriter(file, encoding)) {
+            writer.write(XmpUtilWriter.generateXmpString(entries, this.xmpPreferences));
+            writer.flush();
+        }
+    }
+}

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

@@ -50,6 +50,7 @@ public enum FileType {
     SILVER_PLATTER(Localization.lang("%0 file", "SilverPlatter"), "dat", "txt"),
     SIMPLE_HTML(Localization.lang("%0 file", Localization.lang("Simple HTML")), "html"),
     XMP(Localization.lang("XMP-annotated PDF"), "pdf"),
+    PLAIN_XMP(Localization.lang("%0 file", "XMP"), "xmp"),
 
     AUX(Localization.lang("%0 file", "AUX"), "aux"),
     JSTYLE(Localization.lang("Style file"), "jstyle"),

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;
@@ -82,15 +84,38 @@ 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) {
 
         BibEntry resolvedEntry = XmpUtilWriter.getDefaultOrDatabaseEntry(entry, database);
 
-        DublinCoreExtractor dcExtractor = new DublinCoreExtractor(dcSchema, xmpPreferences, resolvedEntry);
-        dcExtractor.fillDublinCoreSchema();
+        writeToDCSchema(dcSchema, resolvedEntry, 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 xmpPreferences    The user's xmp preferences.
+     */
+    private static void writeToDCSchema(DublinCoreSchema dcSchema, BibEntry entry,
+            XmpPreferences xmpPreferences) {
+
+        DublinCoreExtractor dcExtractor = new DublinCoreExtractor(dcSchema, xmpPreferences, entry);
+        dcExtractor.fillDublinCoreSchema();
+    }
 
     /**
      * Try to write the given BibTexEntry as a DublinCore XMP Schema
@@ -159,6 +184,38 @@ 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, 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(), e);
+            return "";
+        } catch (UnsupportedEncodingException e) {
+            LOGGER.warn("Unsupported encoding to UTF-8 of bib entries in xmp metadata.", e);
+            return "";
+        } catch (IOException e) {
+            LOGGER.warn("IO Exception thrown by closing the output stream.", e);
+            return "";
+        }
+    }
+
     /**
      * Try to write the given BibTexEntry in the Document Information (the
      * properties of the pdf).

src/test/java/org/jabref/logic/exporter/CsvExportFormatTest.java

@@ -10,6 +10,7 @@
 import java.util.Map;
 
 import org.jabref.logic.layout.LayoutFormatterPreferences;
+import org.jabref.logic.xmp.XmpPreferences;
 import org.jabref.model.database.BibDatabaseContext;
 import org.jabref.model.entry.BibEntry;
 
@@ -36,7 +37,8 @@ public void setUp() {
         Map<String, TemplateExporter> customFormats = new HashMap<>();
         LayoutFormatterPreferences layoutPreferences = mock(LayoutFormatterPreferences.class, Answers.RETURNS_DEEP_STUBS);
         SavePreferences savePreferences = mock(SavePreferences.class);
-        ExporterFactory exporterFactory = ExporterFactory.create(customFormats, layoutPreferences, savePreferences);
+        XmpPreferences xmpPreferences = mock(XmpPreferences.class);
+        ExporterFactory exporterFactory = ExporterFactory.create(customFormats, layoutPreferences, savePreferences, xmpPreferences);
 
         exportFormat = exporterFactory.getExporterByName("oocsv").get();
 

src/test/java/org/jabref/logic/exporter/ExporterTest.java

@@ -12,6 +12,7 @@
 import java.util.Map;
 
 import org.jabref.logic.layout.LayoutFormatterPreferences;
+import org.jabref.logic.xmp.XmpPreferences;
 import org.jabref.model.database.BibDatabaseContext;
 import org.jabref.model.entry.BibEntry;
 
@@ -57,7 +58,8 @@ public static Collection<Object[]> exportFormats() {
         Map<String, TemplateExporter> customFormats = new HashMap<>();
         LayoutFormatterPreferences layoutPreferences = mock(LayoutFormatterPreferences.class);
         SavePreferences savePreferences = mock(SavePreferences.class);
-        ExporterFactory exporterFactory = ExporterFactory.create(customFormats, layoutPreferences, savePreferences);
+        XmpPreferences xmpPreferences = mock(XmpPreferences.class);
+        ExporterFactory exporterFactory = ExporterFactory.create(customFormats, layoutPreferences, savePreferences, xmpPreferences);
 
         for (Exporter format : exporterFactory.getExporters()) {
             result.add(new Object[]{format, format.getDisplayName()});

src/test/java/org/jabref/logic/exporter/HtmlExportFormatTest.java

@@ -10,6 +10,7 @@
 import java.util.Map;
 
 import org.jabref.logic.layout.LayoutFormatterPreferences;
+import org.jabref.logic.xmp.XmpPreferences;
 import org.jabref.model.database.BibDatabaseContext;
 import org.jabref.model.entry.BibEntry;
 
@@ -37,7 +38,8 @@ public void setUp() {
         Map<String, TemplateExporter> customFormats = new HashMap<>();
         LayoutFormatterPreferences layoutPreferences = mock(LayoutFormatterPreferences.class, Answers.RETURNS_DEEP_STUBS);
         SavePreferences savePreferences = mock(SavePreferences.class);
-        ExporterFactory exporterFactory = ExporterFactory.create(customFormats, layoutPreferences, savePreferences);
+        XmpPreferences xmpPreferences = mock(XmpPreferences.class);
+        ExporterFactory exporterFactory = ExporterFactory.create(customFormats, layoutPreferences, savePreferences, xmpPreferences);
 
         exportFormat = exporterFactory.getExporterByName("html").get();
 

src/test/java/org/jabref/logic/exporter/XmpExporterTest.java

@@ -0,0 +1,112 @@
+package org.jabref.logic.exporter;
+
+import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.jabref.logic.layout.LayoutFormatterPreferences;
+import org.jabref.logic.xmp.XmpPreferences;
+import org.jabref.model.database.BibDatabaseContext;
+import org.jabref.model.entry.BibEntry;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+import org.mockito.Answers;
+
+import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.mockito.Mockito.mock;
+
+public class XmpExporterTest {
+
+    private Exporter exporter;
+    private BibDatabaseContext databaseContext;
+    private Charset encoding;
+
+    @Rule public TemporaryFolder testFolder = new TemporaryFolder();
+
+    @Before
+    public void setUp() {
+        Map<String, TemplateExporter> customFormats = new HashMap<>();
+        LayoutFormatterPreferences layoutPreferences = mock(LayoutFormatterPreferences.class, Answers.RETURNS_DEEP_STUBS);
+        SavePreferences savePreferences = mock(SavePreferences.class);
+        XmpPreferences xmpPreferences = mock(XmpPreferences.class);
+        ExporterFactory exporterFactory = ExporterFactory.create(customFormats, layoutPreferences, savePreferences, xmpPreferences);
+
+        exporter = exporterFactory.getExporterByName("xmp").get();
+
+        databaseContext = new BibDatabaseContext();
+        encoding = StandardCharsets.UTF_8;
+    }
+
+    @Test
+    public void exportSingleEntry() throws Exception {
+
+        Path file = testFolder.newFile().toPath();
+
+        BibEntry entry = new BibEntry();
+        entry.setField("author", "Alan Turing");
+
+        exporter.export(databaseContext, file, encoding, Arrays.asList(entry));
+
+        List<String> lines = Files.readAllLines(file);
+        assertTrue(lines.size() == 21);
+        assertEquals("<rdf:li>Alan Turing</rdf:li>", lines.get(7).trim());
+    }
+
+    @Test
+    public void writeMutlipleEntriesInASingleFile() throws Exception {
+
+        Path file = testFolder.newFile().toPath();
+
+        BibEntry entryTuring = new BibEntry();
+        entryTuring.setField("author", "Alan Turing");
+
+        BibEntry entryArmbrust = new BibEntry();
+        entryArmbrust.setField("author", "Michael Armbrust");
+        entryArmbrust.setCiteKey("Armbrust2010");
+
+        exporter.export(databaseContext, file, encoding, Arrays.asList(entryTuring, entryArmbrust));
+
+        List<String> lines = Files.readAllLines(file);
+        assertTrue(lines.size() == 39);
+        assertEquals("<rdf:li>Alan Turing</rdf:li>", lines.get(7).trim());
+        assertEquals("<rdf:li>Michael Armbrust</rdf:li>", lines.get(20).trim());
+    }
+
+    @Test
+    public void writeMultipleEntriesInDifferentFiles() throws Exception {
+
+        Path file = testFolder.newFile("split").toPath();
+
+        BibEntry entryTuring = new BibEntry();
+        entryTuring.setField("author", "Alan Turing");
+
+        BibEntry entryArmbrust = new BibEntry();
+        entryArmbrust.setField("author", "Michael Armbrust");
+        entryArmbrust.setCiteKey("Armbrust2010");
+
+        exporter.export(databaseContext, file, encoding, Arrays.asList(entryTuring, entryArmbrust));
+
+        List<String> lines = Files.readAllLines(file);
+        assertTrue(lines.size() == 0);
+
+        Path fileTuring = Paths.get(file.getParent().toString() + "/" + entryTuring.getId() + "_null.xmp");
+        List<String> linesTuring = Files.readAllLines(fileTuring);
+        assertTrue(linesTuring.size() == 21);
+        assertEquals("<rdf:li>Alan Turing</rdf:li>", linesTuring.get(7).trim());
+
+        Path fileArmbrust = Paths.get(file.getParent().toString() + "/" + entryArmbrust.getId() + "_Armbrust2010.xmp");
+        List<String> linesArmbrust = Files.readAllLines(fileArmbrust);
+        assertTrue(linesArmbrust.size() == 26);
+        assertEquals("<rdf:li>Michael Armbrust</rdf:li>", linesArmbrust.get(7).trim());
+    }
+}