jdk/src/java.datatransfer/share/classes/java/awt/datatransfer/SystemFlavorMap.java
changeset 28987 a389d5a5bc45
parent 28231 b608ffcaed74
child 29010 10d6c5d5ebcf
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/java.datatransfer/share/classes/java/awt/datatransfer/SystemFlavorMap.java	Fri Jan 16 18:46:16 2015 +0300
@@ -0,0 +1,1094 @@
+/*
+ * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package java.awt.datatransfer;
+
+import sun.datatransfer.DataFlavorUtil;
+import sun.datatransfer.DesktopDatatransferService;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.lang.ref.SoftReference;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+
+/**
+ * The SystemFlavorMap is a configurable map between "natives" (Strings), which
+ * correspond to platform-specific data formats, and "flavors" (DataFlavors),
+ * which correspond to platform-independent MIME types. This mapping is used
+ * by the data transfer subsystem to transfer data between Java and native
+ * applications, and between Java applications in separate VMs.
+ *
+ * @since 1.2
+ */
+public final class SystemFlavorMap implements FlavorMap, FlavorTable {
+
+    /**
+     * Constant prefix used to tag Java types converted to native platform
+     * type.
+     */
+    private static String JavaMIME = "JAVA_DATAFLAVOR:";
+
+    private static final Object FLAVOR_MAP_KEY = new Object();
+
+    /**
+     * The list of valid, decoded text flavor representation classes, in order
+     * from best to worst.
+     */
+    private static final String[] UNICODE_TEXT_CLASSES = {
+        "java.io.Reader", "java.lang.String", "java.nio.CharBuffer", "\"[C\""
+    };
+
+    /**
+     * The list of valid, encoded text flavor representation classes, in order
+     * from best to worst.
+     */
+    private static final String[] ENCODED_TEXT_CLASSES = {
+        "java.io.InputStream", "java.nio.ByteBuffer", "\"[B\""
+    };
+
+    /**
+     * A String representing text/plain MIME type.
+     */
+    private static final String TEXT_PLAIN_BASE_TYPE = "text/plain";
+
+    /**
+     * A String representing text/html MIME type.
+     */
+    private static final String HTML_TEXT_BASE_TYPE = "text/html";
+
+    /**
+     * Maps native Strings to Lists of DataFlavors (or base type Strings for
+     * text DataFlavors).
+     * Do not use the field directly, use getNativeToFlavor() instead.
+     */
+    private final Map<String, LinkedHashSet<DataFlavor>> nativeToFlavor = new HashMap<>();
+
+    /**
+     * Accessor to nativeToFlavor map.  Since we use lazy initialization we must
+     * use this accessor instead of direct access to the field which may not be
+     * initialized yet.  This method will initialize the field if needed.
+     *
+     * @return nativeToFlavor
+     */
+    private Map<String, LinkedHashSet<DataFlavor>> getNativeToFlavor() {
+        if (!isMapInitialized) {
+            initSystemFlavorMap();
+        }
+        return nativeToFlavor;
+    }
+
+    /**
+     * Maps DataFlavors (or base type Strings for text DataFlavors) to Lists of
+     * native Strings.
+     * Do not use the field directly, use getFlavorToNative() instead.
+     */
+    private final Map<DataFlavor, LinkedHashSet<String>> flavorToNative = new HashMap<>();
+
+    /**
+     * Accessor to flavorToNative map.  Since we use lazy initialization we must
+     * use this accessor instead of direct access to the field which may not be
+     * initialized yet.  This method will initialize the field if needed.
+     *
+     * @return flavorToNative
+     */
+    private synchronized Map<DataFlavor, LinkedHashSet<String>> getFlavorToNative() {
+        if (!isMapInitialized) {
+            initSystemFlavorMap();
+        }
+        return flavorToNative;
+    }
+
+    /**
+     * Maps a text DataFlavor primary mime-type to the native. Used only to store
+     * standard mappings registered in the flavormap.properties
+     * Do not use this field directly, use getTextTypeToNative() instead.
+     */
+    private Map<String, LinkedHashSet<String>> textTypeToNative = new HashMap<>();
+
+    /**
+     * Shows if the object has been initialized.
+     */
+    private boolean isMapInitialized = false;
+
+    /**
+     * An accessor to textTypeToNative map.  Since we use lazy initialization we
+     * must use this accessor instead of direct access to the field which may not
+     * be initialized yet. This method will initialize the field if needed.
+     *
+     * @return textTypeToNative
+     */
+    private synchronized Map<String, LinkedHashSet<String>> getTextTypeToNative() {
+        if (!isMapInitialized) {
+            initSystemFlavorMap();
+            // From this point the map should not be modified
+            textTypeToNative = Collections.unmodifiableMap(textTypeToNative);
+        }
+        return textTypeToNative;
+    }
+
+    /**
+     * Caches the result of getNativesForFlavor(). Maps DataFlavors to
+     * SoftReferences which reference LinkedHashSet of String natives.
+     */
+    private final SoftCache<DataFlavor, String> nativesForFlavorCache = new SoftCache<>();
+
+    /**
+     * Caches the result getFlavorsForNative(). Maps String natives to
+     * SoftReferences which reference LinkedHashSet of DataFlavors.
+     */
+    private final SoftCache<String, DataFlavor> flavorsForNativeCache = new SoftCache<>();
+
+    /**
+     * Dynamic mapping generation used for text mappings should not be applied
+     * to the DataFlavors and String natives for which the mappings have been
+     * explicitly specified with setFlavorsForNative() or
+     * setNativesForFlavor(). This keeps all such keys.
+     */
+    private Set<Object> disabledMappingGenerationKeys = new HashSet<>();
+
+    /**
+     * Returns the default FlavorMap for this thread's ClassLoader.
+     *
+     * @return the default FlavorMap for this thread's ClassLoader
+     */
+    public static FlavorMap getDefaultFlavorMap() {
+        return DataFlavorUtil.getDesktopService().getFlavorMap(SystemFlavorMap::new);
+    }
+
+    private SystemFlavorMap() {
+    }
+
+    /**
+     * Initializes a SystemFlavorMap by reading flavormap.properties
+     * For thread-safety must be called under lock on this.
+     */
+    private void initSystemFlavorMap() {
+        if (isMapInitialized) {
+            return;
+        }
+        isMapInitialized = true;
+
+        InputStream is = SystemFlavorMap.class.getResourceAsStream("/sun/datatransfer/resources/flavormap.properties");
+        if (is == null) {
+            throw new InternalError("Default flavor mapping not found");
+        }
+
+        try (InputStreamReader isr = new InputStreamReader(is);
+             BufferedReader reader = new BufferedReader(isr)) {
+            String line;
+            while ((line = reader.readLine()) != null) {
+                line = line.trim();
+                if (line.startsWith("#") || line.isEmpty()) continue;
+                while (line.endsWith("\\")) {
+                    line = line.substring(0, line.length() - 1) + reader.readLine().trim();
+                }
+                int delimiterPosition = line.indexOf('=');
+                String key = line.substring(0, delimiterPosition).replaceAll("\\ ", " ");
+                String[] values = line.substring(delimiterPosition + 1, line.length()).split(",");
+                for (String value : values) {
+                    try {
+                        value = loadConvert(value);
+                        MimeType mime = new MimeType(value);
+                        if ("text".equals(mime.getPrimaryType())) {
+                            String charset = mime.getParameter("charset");
+                            if (DataFlavorUtil.doesSubtypeSupportCharset(mime.getSubType(), charset))
+                            {
+                                // We need to store the charset and eoln
+                                // parameters, if any, so that the
+                                // DataTransferer will have this information
+                                // for conversion into the native format.
+                                DesktopDatatransferService desktopService =
+                                        DataFlavorUtil.getDesktopService();
+                                if (desktopService.isDesktopPresent()) {
+                                    desktopService.registerTextFlavorProperties(
+                                            key, charset,
+                                            mime.getParameter("eoln"),
+                                            mime.getParameter("terminators"));
+                                }
+                            }
+
+                            // But don't store any of these parameters in the
+                            // DataFlavor itself for any text natives (even
+                            // non-charset ones). The SystemFlavorMap will
+                            // synthesize the appropriate mappings later.
+                            mime.removeParameter("charset");
+                            mime.removeParameter("class");
+                            mime.removeParameter("eoln");
+                            mime.removeParameter("terminators");
+                            value = mime.toString();
+                        }
+                    } catch (MimeTypeParseException e) {
+                        e.printStackTrace();
+                        continue;
+                    }
+
+                    DataFlavor flavor;
+                    try {
+                        flavor = new DataFlavor(value);
+                    } catch (Exception e) {
+                        try {
+                            flavor = new DataFlavor(value, null);
+                        } catch (Exception ee) {
+                            ee.printStackTrace();
+                            continue;
+                        }
+                    }
+
+                    final LinkedHashSet<DataFlavor> dfs = new LinkedHashSet<>();
+                    dfs.add(flavor);
+
+                    if ("text".equals(flavor.getPrimaryType())) {
+                        dfs.addAll(convertMimeTypeToDataFlavors(value));
+                        store(flavor.mimeType.getBaseType(), key, getTextTypeToNative());
+                    }
+
+                    for (DataFlavor df : dfs) {
+                        store(df, key, getFlavorToNative());
+                        store(key, df, getNativeToFlavor());
+                    }
+                }
+            }
+        } catch (IOException e) {
+            throw new InternalError("Error reading default flavor mapping", e);
+        }
+    }
+
+    // Copied from java.util.Properties
+    private static String loadConvert(String theString) {
+        char aChar;
+        int len = theString.length();
+        StringBuilder outBuffer = new StringBuilder(len);
+
+        for (int x = 0; x < len; ) {
+            aChar = theString.charAt(x++);
+            if (aChar == '\\') {
+                aChar = theString.charAt(x++);
+                if (aChar == 'u') {
+                    // Read the xxxx
+                    int value = 0;
+                    for (int i = 0; i < 4; i++) {
+                        aChar = theString.charAt(x++);
+                        switch (aChar) {
+                            case '0': case '1': case '2': case '3': case '4':
+                            case '5': case '6': case '7': case '8': case '9': {
+                                value = (value << 4) + aChar - '0';
+                                break;
+                            }
+                            case 'a': case 'b': case 'c':
+                            case 'd': case 'e': case 'f': {
+                                value = (value << 4) + 10 + aChar - 'a';
+                                break;
+                            }
+                            case 'A': case 'B': case 'C':
+                            case 'D': case 'E': case 'F': {
+                                value = (value << 4) + 10 + aChar - 'A';
+                                break;
+                            }
+                            default: {
+                                throw new IllegalArgumentException(
+                                        "Malformed \\uxxxx encoding.");
+                            }
+                        }
+                    }
+                    outBuffer.append((char)value);
+                } else {
+                    if (aChar == 't') {
+                        aChar = '\t';
+                    } else if (aChar == 'r') {
+                        aChar = '\r';
+                    } else if (aChar == 'n') {
+                        aChar = '\n';
+                    } else if (aChar == 'f') {
+                        aChar = '\f';
+                    }
+                    outBuffer.append(aChar);
+                }
+            } else {
+                outBuffer.append(aChar);
+            }
+        }
+        return outBuffer.toString();
+    }
+
+    /**
+     * Stores the listed object under the specified hash key in map. Unlike a
+     * standard map, the listed object will not replace any object already at
+     * the appropriate Map location, but rather will be appended to a List
+     * stored in that location.
+     */
+    private <H, L> void store(H hashed, L listed, Map<H, LinkedHashSet<L>> map) {
+        LinkedHashSet<L> list = map.get(hashed);
+        if (list == null) {
+            list = new LinkedHashSet<>(1);
+            map.put(hashed, list);
+        }
+        if (!list.contains(listed)) {
+            list.add(listed);
+        }
+    }
+
+    /**
+     * Semantically equivalent to 'nativeToFlavor.get(nat)'. This method
+     * handles the case where 'nat' is not found in 'nativeToFlavor'. In that
+     * case, a new DataFlavor is synthesized, stored, and returned, if and
+     * only if the specified native is encoded as a Java MIME type.
+     */
+    private LinkedHashSet<DataFlavor> nativeToFlavorLookup(String nat) {
+        LinkedHashSet<DataFlavor> flavors = getNativeToFlavor().get(nat);
+
+        if (nat != null && !disabledMappingGenerationKeys.contains(nat)) {
+            DesktopDatatransferService desktopService = DataFlavorUtil.getDesktopService();
+            if (desktopService.isDesktopPresent()) {
+                LinkedHashSet<DataFlavor> platformFlavors =
+                        desktopService.getPlatformMappingsForNative(nat);
+                if (!platformFlavors.isEmpty()) {
+                    if (flavors != null) {
+                        // Prepending the platform-specific mappings ensures
+                        // that the flavors added with
+                        // addFlavorForUnencodedNative() are at the end of
+                        // list.
+                        platformFlavors.addAll(flavors);
+                    }
+                    flavors = platformFlavors;
+                }
+            }
+        }
+
+        if (flavors == null && isJavaMIMEType(nat)) {
+            String decoded = decodeJavaMIMEType(nat);
+            DataFlavor flavor = null;
+
+            try {
+                flavor = new DataFlavor(decoded);
+            } catch (Exception e) {
+                System.err.println("Exception \"" + e.getClass().getName() +
+                                   ": " + e.getMessage()  +
+                                   "\"while constructing DataFlavor for: " +
+                                   decoded);
+            }
+
+            if (flavor != null) {
+                flavors = new LinkedHashSet<>(1);
+                getNativeToFlavor().put(nat, flavors);
+                flavors.add(flavor);
+                flavorsForNativeCache.remove(nat);
+
+                LinkedHashSet<String> natives = getFlavorToNative().get(flavor);
+                if (natives == null) {
+                    natives = new LinkedHashSet<>(1);
+                    getFlavorToNative().put(flavor, natives);
+                }
+                natives.add(nat);
+                nativesForFlavorCache.remove(flavor);
+            }
+        }
+
+        return (flavors != null) ? flavors : new LinkedHashSet<>(0);
+    }
+
+    /**
+     * Semantically equivalent to 'flavorToNative.get(flav)'. This method
+     * handles the case where 'flav' is not found in 'flavorToNative' depending
+     * on the value of passes 'synthesize' parameter. If 'synthesize' is
+     * SYNTHESIZE_IF_NOT_FOUND a native is synthesized, stored, and returned by
+     * encoding the DataFlavor's MIME type. Otherwise an empty List is returned
+     * and 'flavorToNative' remains unaffected.
+     */
+    private LinkedHashSet<String> flavorToNativeLookup(final DataFlavor flav,
+                                                       final boolean synthesize) {
+
+        LinkedHashSet<String> natives = getFlavorToNative().get(flav);
+
+        if (flav != null && !disabledMappingGenerationKeys.contains(flav)) {
+            DesktopDatatransferService desktopService = DataFlavorUtil.getDesktopService();
+            if (desktopService.isDesktopPresent()) {
+                LinkedHashSet<String> platformNatives =
+                        desktopService.getPlatformMappingsForFlavor(flav);
+                if (!platformNatives.isEmpty()) {
+                    if (natives != null) {
+                        // Prepend the platform-specific mappings to ensure
+                        // that the natives added with
+                        // addUnencodedNativeForFlavor() are at the end of
+                        // list.
+                        platformNatives.addAll(natives);
+                    }
+                    natives = platformNatives;
+                }
+            }
+        }
+
+        if (natives == null) {
+            if (synthesize) {
+                String encoded = encodeDataFlavor(flav);
+                natives = new LinkedHashSet<>(1);
+                getFlavorToNative().put(flav, natives);
+                natives.add(encoded);
+
+                LinkedHashSet<DataFlavor> flavors = getNativeToFlavor().get(encoded);
+                if (flavors == null) {
+                    flavors = new LinkedHashSet<>(1);
+                    getNativeToFlavor().put(encoded, flavors);
+                }
+                flavors.add(flav);
+
+                nativesForFlavorCache.remove(flav);
+                flavorsForNativeCache.remove(encoded);
+            } else {
+                natives = new LinkedHashSet<>(0);
+            }
+        }
+
+        return new LinkedHashSet<>(natives);
+    }
+
+    /**
+     * Returns a <code>List</code> of <code>String</code> natives to which the
+     * specified <code>DataFlavor</code> can be translated by the data transfer
+     * subsystem. The <code>List</code> will be sorted from best native to
+     * worst. That is, the first native will best reflect data in the specified
+     * flavor to the underlying native platform.
+     * <p>
+     * If the specified <code>DataFlavor</code> is previously unknown to the
+     * data transfer subsystem and the data transfer subsystem is unable to
+     * translate this <code>DataFlavor</code> to any existing native, then
+     * invoking this method will establish a
+     * mapping in both directions between the specified <code>DataFlavor</code>
+     * and an encoded version of its MIME type as its native.
+     *
+     * @param flav the <code>DataFlavor</code> whose corresponding natives
+     *        should be returned. If <code>null</code> is specified, all
+     *        natives currently known to the data transfer subsystem are
+     *        returned in a non-deterministic order.
+     * @return a <code>java.util.List</code> of <code>java.lang.String</code>
+     *         objects which are platform-specific representations of platform-
+     *         specific data formats
+     *
+     * @see #encodeDataFlavor
+     * @since 1.4
+     */
+    @Override
+    public synchronized List<String> getNativesForFlavor(DataFlavor flav) {
+        LinkedHashSet<String> retval = nativesForFlavorCache.check(flav);
+        if (retval != null) {
+            return new ArrayList<>(retval);
+        }
+
+        if (flav == null) {
+            retval = new LinkedHashSet<>(getNativeToFlavor().keySet());
+        } else if (disabledMappingGenerationKeys.contains(flav)) {
+            // In this case we shouldn't synthesize a native for this flavor,
+            // since its mappings were explicitly specified.
+            retval = flavorToNativeLookup(flav, false);
+        } else if (DataFlavorUtil.isFlavorCharsetTextType(flav)) {
+            retval = new LinkedHashSet<>(0);
+
+            // For text/* flavors, flavor-to-native mappings specified in
+            // flavormap.properties are stored per flavor's base type.
+            if ("text".equals(flav.getPrimaryType())) {
+                LinkedHashSet<String> textTypeNatives =
+                        getTextTypeToNative().get(flav.mimeType.getBaseType());
+                if (textTypeNatives != null) {
+                    retval.addAll(textTypeNatives);
+                }
+            }
+
+            // Also include text/plain natives, but don't duplicate Strings
+            LinkedHashSet<String> textTypeNatives =
+                    getTextTypeToNative().get(TEXT_PLAIN_BASE_TYPE);
+            if (textTypeNatives != null) {
+                retval.addAll(textTypeNatives);
+            }
+
+            if (retval.isEmpty()) {
+                retval = flavorToNativeLookup(flav, true);
+            } else {
+                // In this branch it is guaranteed that natives explicitly
+                // listed for flav's MIME type were added with
+                // addUnencodedNativeForFlavor(), so they have lower priority.
+                retval.addAll(flavorToNativeLookup(flav, false));
+            }
+        } else if (DataFlavorUtil.isFlavorNoncharsetTextType(flav)) {
+            retval = getTextTypeToNative().get(flav.mimeType.getBaseType());
+
+            if (retval == null || retval.isEmpty()) {
+                retval = flavorToNativeLookup(flav, true);
+            } else {
+                // In this branch it is guaranteed that natives explicitly
+                // listed for flav's MIME type were added with
+                // addUnencodedNativeForFlavor(), so they have lower priority.
+                retval.addAll(flavorToNativeLookup(flav, false));
+            }
+        } else {
+            retval = flavorToNativeLookup(flav, true);
+        }
+
+        nativesForFlavorCache.put(flav, retval);
+        // Create a copy, because client code can modify the returned list.
+        return new ArrayList<>(retval);
+    }
+
+    /**
+     * Returns a <code>List</code> of <code>DataFlavor</code>s to which the
+     * specified <code>String</code> native can be translated by the data
+     * transfer subsystem. The <code>List</code> will be sorted from best
+     * <code>DataFlavor</code> to worst. That is, the first
+     * <code>DataFlavor</code> will best reflect data in the specified
+     * native to a Java application.
+     * <p>
+     * If the specified native is previously unknown to the data transfer
+     * subsystem, and that native has been properly encoded, then invoking this
+     * method will establish a mapping in both directions between the specified
+     * native and a <code>DataFlavor</code> whose MIME type is a decoded
+     * version of the native.
+     * <p>
+     * If the specified native is not a properly encoded native and the
+     * mappings for this native have not been altered with
+     * <code>setFlavorsForNative</code>, then the contents of the
+     * <code>List</code> is platform dependent, but <code>null</code>
+     * cannot be returned.
+     *
+     * @param nat the native whose corresponding <code>DataFlavor</code>s
+     *        should be returned. If <code>null</code> is specified, all
+     *        <code>DataFlavor</code>s currently known to the data transfer
+     *        subsystem are returned in a non-deterministic order.
+     * @return a <code>java.util.List</code> of <code>DataFlavor</code>
+     *         objects into which platform-specific data in the specified,
+     *         platform-specific native can be translated
+     *
+     * @see #encodeJavaMIMEType
+     * @since 1.4
+     */
+    @Override
+    public synchronized List<DataFlavor> getFlavorsForNative(String nat) {
+        LinkedHashSet<DataFlavor> returnValue = flavorsForNativeCache.check(nat);
+        if (returnValue != null) {
+            return new ArrayList<>(returnValue);
+        } else {
+            returnValue = new LinkedHashSet<>();
+        }
+
+        if (nat == null) {
+            for (String n : getNativesForFlavor(null)) {
+                returnValue.addAll(getFlavorsForNative(n));
+            }
+        } else {
+            final LinkedHashSet<DataFlavor> flavors = nativeToFlavorLookup(nat);
+            if (disabledMappingGenerationKeys.contains(nat)) {
+                return new ArrayList<>(flavors);
+            }
+
+            final LinkedHashSet<DataFlavor> flavorsWithSynthesized =
+                    nativeToFlavorLookup(nat);
+
+            for (DataFlavor df : flavorsWithSynthesized) {
+                returnValue.add(df);
+                if ("text".equals(df.getPrimaryType())) {
+                    String baseType = df.mimeType.getBaseType();
+                    returnValue.addAll(convertMimeTypeToDataFlavors(baseType));
+                }
+            }
+        }
+        flavorsForNativeCache.put(nat, returnValue);
+        return new ArrayList<>(returnValue);
+    }
+
+    @SuppressWarnings("deprecation")
+    private static Set<DataFlavor> convertMimeTypeToDataFlavors(
+        final String baseType) {
+
+        final Set<DataFlavor> returnValue = new LinkedHashSet<>();
+
+        String subType = null;
+
+        try {
+            final MimeType mimeType = new MimeType(baseType);
+            subType = mimeType.getSubType();
+        } catch (MimeTypeParseException mtpe) {
+            // Cannot happen, since we checked all mappings
+            // on load from flavormap.properties.
+        }
+
+        if (DataFlavorUtil.doesSubtypeSupportCharset(subType, null)) {
+            if (TEXT_PLAIN_BASE_TYPE.equals(baseType))
+            {
+                returnValue.add(DataFlavor.stringFlavor);
+            }
+
+            for (String unicodeClassName : UNICODE_TEXT_CLASSES) {
+                final String mimeType = baseType + ";charset=Unicode;class=" +
+                                            unicodeClassName;
+
+                final LinkedHashSet<String> mimeTypes =
+                    handleHtmlMimeTypes(baseType, mimeType);
+                for (String mt : mimeTypes) {
+                    DataFlavor toAdd = null;
+                    try {
+                        toAdd = new DataFlavor(mt);
+                    } catch (ClassNotFoundException cannotHappen) {
+                    }
+                    returnValue.add(toAdd);
+                }
+            }
+
+            for (String charset : DataFlavorUtil.standardEncodings()) {
+
+                for (String encodedTextClass : ENCODED_TEXT_CLASSES) {
+                    final String mimeType =
+                            baseType + ";charset=" + charset +
+                            ";class=" + encodedTextClass;
+
+                    final LinkedHashSet<String> mimeTypes =
+                        handleHtmlMimeTypes(baseType, mimeType);
+
+                    for (String mt : mimeTypes) {
+
+                        DataFlavor df = null;
+
+                        try {
+                            df = new DataFlavor(mt);
+                            // Check for equality to plainTextFlavor so
+                            // that we can ensure that the exact charset of
+                            // plainTextFlavor, not the canonical charset
+                            // or another equivalent charset with a
+                            // different name, is used.
+                            if (df.equals(DataFlavor.plainTextFlavor)) {
+                                df = DataFlavor.plainTextFlavor;
+                            }
+                        } catch (ClassNotFoundException cannotHappen) {
+                        }
+
+                        returnValue.add(df);
+                    }
+                }
+            }
+
+            if (TEXT_PLAIN_BASE_TYPE.equals(baseType))
+            {
+                returnValue.add(DataFlavor.plainTextFlavor);
+            }
+        } else {
+            // Non-charset text natives should be treated as
+            // opaque, 8-bit data in any of its various
+            // representations.
+            for (String encodedTextClassName : ENCODED_TEXT_CLASSES) {
+                DataFlavor toAdd = null;
+                try {
+                    toAdd = new DataFlavor(baseType +
+                         ";class=" + encodedTextClassName);
+                } catch (ClassNotFoundException cannotHappen) {
+                }
+                returnValue.add(toAdd);
+            }
+        }
+        return returnValue;
+    }
+
+    private static final String [] htmlDocumentTypes =
+            new String [] {"all", "selection", "fragment"};
+
+    private static LinkedHashSet<String> handleHtmlMimeTypes(String baseType,
+                                                             String mimeType) {
+
+        LinkedHashSet<String> returnValues = new LinkedHashSet<>();
+
+        if (HTML_TEXT_BASE_TYPE.equals(baseType)) {
+            for (String documentType : htmlDocumentTypes) {
+                returnValues.add(mimeType + ";document=" + documentType);
+            }
+        } else {
+            returnValues.add(mimeType);
+        }
+
+        return returnValues;
+    }
+
+    /**
+     * Returns a <code>Map</code> of the specified <code>DataFlavor</code>s to
+     * their most preferred <code>String</code> native. Each native value will
+     * be the same as the first native in the List returned by
+     * <code>getNativesForFlavor</code> for the specified flavor.
+     * <p>
+     * If a specified <code>DataFlavor</code> is previously unknown to the
+     * data transfer subsystem, then invoking this method will establish a
+     * mapping in both directions between the specified <code>DataFlavor</code>
+     * and an encoded version of its MIME type as its native.
+     *
+     * @param flavors an array of <code>DataFlavor</code>s which will be the
+     *        key set of the returned <code>Map</code>. If <code>null</code> is
+     *        specified, a mapping of all <code>DataFlavor</code>s known to the
+     *        data transfer subsystem to their most preferred
+     *        <code>String</code> natives will be returned.
+     * @return a <code>java.util.Map</code> of <code>DataFlavor</code>s to
+     *         <code>String</code> natives
+     *
+     * @see #getNativesForFlavor
+     * @see #encodeDataFlavor
+     */
+    @Override
+    public synchronized Map<DataFlavor,String> getNativesForFlavors(DataFlavor[] flavors)
+    {
+        // Use getNativesForFlavor to generate extra natives for text flavors
+        // and stringFlavor
+
+        if (flavors == null) {
+            List<DataFlavor> flavor_list = getFlavorsForNative(null);
+            flavors = new DataFlavor[flavor_list.size()];
+            flavor_list.toArray(flavors);
+        }
+
+        Map<DataFlavor, String> retval = new HashMap<>(flavors.length, 1.0f);
+        for (DataFlavor flavor : flavors) {
+            List<String> natives = getNativesForFlavor(flavor);
+            String nat = (natives.isEmpty()) ? null : natives.get(0);
+            retval.put(flavor, nat);
+        }
+
+        return retval;
+    }
+
+    /**
+     * Returns a <code>Map</code> of the specified <code>String</code> natives
+     * to their most preferred <code>DataFlavor</code>. Each
+     * <code>DataFlavor</code> value will be the same as the first
+     * <code>DataFlavor</code> in the List returned by
+     * <code>getFlavorsForNative</code> for the specified native.
+     * <p>
+     * If a specified native is previously unknown to the data transfer
+     * subsystem, and that native has been properly encoded, then invoking this
+     * method will establish a mapping in both directions between the specified
+     * native and a <code>DataFlavor</code> whose MIME type is a decoded
+     * version of the native.
+     *
+     * @param natives an array of <code>String</code>s which will be the
+     *        key set of the returned <code>Map</code>. If <code>null</code> is
+     *        specified, a mapping of all supported <code>String</code> natives
+     *        to their most preferred <code>DataFlavor</code>s will be
+     *        returned.
+     * @return a <code>java.util.Map</code> of <code>String</code> natives to
+     *         <code>DataFlavor</code>s
+     *
+     * @see #getFlavorsForNative
+     * @see #encodeJavaMIMEType
+     */
+    @Override
+    public synchronized Map<String,DataFlavor> getFlavorsForNatives(String[] natives)
+    {
+        // Use getFlavorsForNative to generate extra flavors for text natives
+        if (natives == null) {
+            List<String> nativesList = getNativesForFlavor(null);
+            natives = new String[nativesList.size()];
+            nativesList.toArray(natives);
+        }
+
+        Map<String, DataFlavor> retval = new HashMap<>(natives.length, 1.0f);
+        for (String aNative : natives) {
+            List<DataFlavor> flavors = getFlavorsForNative(aNative);
+            DataFlavor flav = (flavors.isEmpty())? null : flavors.get(0);
+            retval.put(aNative, flav);
+        }
+        return retval;
+    }
+
+    /**
+     * Adds a mapping from the specified <code>DataFlavor</code> (and all
+     * <code>DataFlavor</code>s equal to the specified <code>DataFlavor</code>)
+     * to the specified <code>String</code> native.
+     * Unlike <code>getNativesForFlavor</code>, the mapping will only be
+     * established in one direction, and the native will not be encoded. To
+     * establish a two-way mapping, call
+     * <code>addFlavorForUnencodedNative</code> as well. The new mapping will
+     * be of lower priority than any existing mapping.
+     * This method has no effect if a mapping from the specified or equal
+     * <code>DataFlavor</code> to the specified <code>String</code> native
+     * already exists.
+     *
+     * @param flav the <code>DataFlavor</code> key for the mapping
+     * @param nat the <code>String</code> native value for the mapping
+     * @throws NullPointerException if flav or nat is <code>null</code>
+     *
+     * @see #addFlavorForUnencodedNative
+     * @since 1.4
+     */
+    public synchronized void addUnencodedNativeForFlavor(DataFlavor flav,
+                                                         String nat) {
+        Objects.requireNonNull(nat, "Null native not permitted");
+        Objects.requireNonNull(flav, "Null flavor not permitted");
+
+        LinkedHashSet<String> natives = getFlavorToNative().get(flav);
+        if (natives == null) {
+            natives = new LinkedHashSet<>(1);
+            getFlavorToNative().put(flav, natives);
+        }
+        natives.add(nat);
+        nativesForFlavorCache.remove(flav);
+    }
+
+    /**
+     * Discards the current mappings for the specified <code>DataFlavor</code>
+     * and all <code>DataFlavor</code>s equal to the specified
+     * <code>DataFlavor</code>, and creates new mappings to the
+     * specified <code>String</code> natives.
+     * Unlike <code>getNativesForFlavor</code>, the mappings will only be
+     * established in one direction, and the natives will not be encoded. To
+     * establish two-way mappings, call <code>setFlavorsForNative</code>
+     * as well. The first native in the array will represent the highest
+     * priority mapping. Subsequent natives will represent mappings of
+     * decreasing priority.
+     * <p>
+     * If the array contains several elements that reference equal
+     * <code>String</code> natives, this method will establish new mappings
+     * for the first of those elements and ignore the rest of them.
+     * <p>
+     * It is recommended that client code not reset mappings established by the
+     * data transfer subsystem. This method should only be used for
+     * application-level mappings.
+     *
+     * @param flav the <code>DataFlavor</code> key for the mappings
+     * @param natives the <code>String</code> native values for the mappings
+     * @throws NullPointerException if flav or natives is <code>null</code>
+     *         or if natives contains <code>null</code> elements
+     *
+     * @see #setFlavorsForNative
+     * @since 1.4
+     */
+    public synchronized void setNativesForFlavor(DataFlavor flav,
+                                                 String[] natives) {
+        Objects.requireNonNull(natives, "Null natives not permitted");
+        Objects.requireNonNull(flav, "Null flavors not permitted");
+
+        getFlavorToNative().remove(flav);
+        for (String aNative : natives) {
+            addUnencodedNativeForFlavor(flav, aNative);
+        }
+        disabledMappingGenerationKeys.add(flav);
+        nativesForFlavorCache.remove(flav);
+    }
+
+    /**
+     * Adds a mapping from a single <code>String</code> native to a single
+     * <code>DataFlavor</code>. Unlike <code>getFlavorsForNative</code>, the
+     * mapping will only be established in one direction, and the native will
+     * not be encoded. To establish a two-way mapping, call
+     * <code>addUnencodedNativeForFlavor</code> as well. The new mapping will
+     * be of lower priority than any existing mapping.
+     * This method has no effect if a mapping from the specified
+     * <code>String</code> native to the specified or equal
+     * <code>DataFlavor</code> already exists.
+     *
+     * @param nat the <code>String</code> native key for the mapping
+     * @param flav the <code>DataFlavor</code> value for the mapping
+     * @throws NullPointerException if nat or flav is <code>null</code>
+     *
+     * @see #addUnencodedNativeForFlavor
+     * @since 1.4
+     */
+    public synchronized void addFlavorForUnencodedNative(String nat,
+                                                         DataFlavor flav) {
+        Objects.requireNonNull(nat, "Null native not permitted");
+        Objects.requireNonNull(flav, "Null flavor not permitted");
+
+        LinkedHashSet<DataFlavor> flavors = getNativeToFlavor().get(nat);
+        if (flavors == null) {
+            flavors = new LinkedHashSet<>(1);
+            getNativeToFlavor().put(nat, flavors);
+        }
+        flavors.add(flav);
+        flavorsForNativeCache.remove(nat);
+    }
+
+    /**
+     * Discards the current mappings for the specified <code>String</code>
+     * native, and creates new mappings to the specified
+     * <code>DataFlavor</code>s. Unlike <code>getFlavorsForNative</code>, the
+     * mappings will only be established in one direction, and the natives need
+     * not be encoded. To establish two-way mappings, call
+     * <code>setNativesForFlavor</code> as well. The first
+     * <code>DataFlavor</code> in the array will represent the highest priority
+     * mapping. Subsequent <code>DataFlavor</code>s will represent mappings of
+     * decreasing priority.
+     * <p>
+     * If the array contains several elements that reference equal
+     * <code>DataFlavor</code>s, this method will establish new mappings
+     * for the first of those elements and ignore the rest of them.
+     * <p>
+     * It is recommended that client code not reset mappings established by the
+     * data transfer subsystem. This method should only be used for
+     * application-level mappings.
+     *
+     * @param nat the <code>String</code> native key for the mappings
+     * @param flavors the <code>DataFlavor</code> values for the mappings
+     * @throws NullPointerException if nat or flavors is <code>null</code>
+     *         or if flavors contains <code>null</code> elements
+     *
+     * @see #setNativesForFlavor
+     * @since 1.4
+     */
+    public synchronized void setFlavorsForNative(String nat,
+                                                 DataFlavor[] flavors) {
+        Objects.requireNonNull(nat, "Null native not permitted");
+        Objects.requireNonNull(flavors, "Null flavors not permitted");
+
+        getNativeToFlavor().remove(nat);
+        for (DataFlavor flavor : flavors) {
+            addFlavorForUnencodedNative(nat, flavor);
+        }
+        disabledMappingGenerationKeys.add(nat);
+        flavorsForNativeCache.remove(nat);
+    }
+
+    /**
+     * Encodes a MIME type for use as a <code>String</code> native. The format
+     * of an encoded representation of a MIME type is implementation-dependent.
+     * The only restrictions are:
+     * <ul>
+     * <li>The encoded representation is <code>null</code> if and only if the
+     * MIME type <code>String</code> is <code>null</code>.</li>
+     * <li>The encoded representations for two non-<code>null</code> MIME type
+     * <code>String</code>s are equal if and only if these <code>String</code>s
+     * are equal according to <code>String.equals(Object)</code>.</li>
+     * </ul>
+     * <p>
+     * The reference implementation of this method returns the specified MIME
+     * type <code>String</code> prefixed with <code>JAVA_DATAFLAVOR:</code>.
+     *
+     * @param mimeType the MIME type to encode
+     * @return the encoded <code>String</code>, or <code>null</code> if
+     *         mimeType is <code>null</code>
+     */
+    public static String encodeJavaMIMEType(String mimeType) {
+        return (mimeType != null)
+            ? JavaMIME + mimeType
+            : null;
+    }
+
+    /**
+     * Encodes a <code>DataFlavor</code> for use as a <code>String</code>
+     * native. The format of an encoded <code>DataFlavor</code> is
+     * implementation-dependent. The only restrictions are:
+     * <ul>
+     * <li>The encoded representation is <code>null</code> if and only if the
+     * specified <code>DataFlavor</code> is <code>null</code> or its MIME type
+     * <code>String</code> is <code>null</code>.</li>
+     * <li>The encoded representations for two non-<code>null</code>
+     * <code>DataFlavor</code>s with non-<code>null</code> MIME type
+     * <code>String</code>s are equal if and only if the MIME type
+     * <code>String</code>s of these <code>DataFlavor</code>s are equal
+     * according to <code>String.equals(Object)</code>.</li>
+     * </ul>
+     * <p>
+     * The reference implementation of this method returns the MIME type
+     * <code>String</code> of the specified <code>DataFlavor</code> prefixed
+     * with <code>JAVA_DATAFLAVOR:</code>.
+     *
+     * @param flav the <code>DataFlavor</code> to encode
+     * @return the encoded <code>String</code>, or <code>null</code> if
+     *         flav is <code>null</code> or has a <code>null</code> MIME type
+     */
+    public static String encodeDataFlavor(DataFlavor flav) {
+        return (flav != null)
+            ? SystemFlavorMap.encodeJavaMIMEType(flav.getMimeType())
+            : null;
+    }
+
+    /**
+     * Returns whether the specified <code>String</code> is an encoded Java
+     * MIME type.
+     *
+     * @param str the <code>String</code> to test
+     * @return <code>true</code> if the <code>String</code> is encoded;
+     *         <code>false</code> otherwise
+     */
+    public static boolean isJavaMIMEType(String str) {
+        return (str != null && str.startsWith(JavaMIME, 0));
+    }
+
+    /**
+     * Decodes a <code>String</code> native for use as a Java MIME type.
+     *
+     * @param nat the <code>String</code> to decode
+     * @return the decoded Java MIME type, or <code>null</code> if nat is not
+     *         an encoded <code>String</code> native
+     */
+    public static String decodeJavaMIMEType(String nat) {
+        return (isJavaMIMEType(nat))
+            ? nat.substring(JavaMIME.length(), nat.length()).trim()
+            : null;
+    }
+
+    /**
+     * Decodes a <code>String</code> native for use as a
+     * <code>DataFlavor</code>.
+     *
+     * @param nat the <code>String</code> to decode
+     * @return the decoded <code>DataFlavor</code>, or <code>null</code> if
+     *         nat is not an encoded <code>String</code> native
+     * @throws ClassNotFoundException if the class of the data flavor
+     * is not loaded
+     */
+    public static DataFlavor decodeDataFlavor(String nat)
+        throws ClassNotFoundException
+    {
+        String retval_str = SystemFlavorMap.decodeJavaMIMEType(nat);
+        return (retval_str != null)
+            ? new DataFlavor(retval_str)
+            : null;
+    }
+
+    private static final class SoftCache<K, V> {
+        Map<K, SoftReference<LinkedHashSet<V>>> cache;
+
+        public void put(K key, LinkedHashSet<V> value) {
+            if (cache == null) {
+                cache = new HashMap<>(1);
+            }
+            cache.put(key, new SoftReference<>(value));
+        }
+
+        public void remove(K key) {
+            if (cache == null) return;
+            cache.remove(null);
+            cache.remove(key);
+        }
+
+        public LinkedHashSet<V> check(K key) {
+            if (cache == null) return null;
+            SoftReference<LinkedHashSet<V>> ref = cache.get(key);
+            if (ref != null) {
+                return ref.get();
+            }
+            return null;
+        }
+    }
+}