ratpack.file.internal.ActivationBackedMimeTypes.java Source code

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Here is the source code for ratpack.file.internal.ActivationBackedMimeTypes.java

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/*
 * Copyright 2013 the original author or authors.
 *
 * 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 ratpack.file.internal;

import com.google.common.base.Function;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;
import com.google.common.collect.Sets;
import ratpack.file.MimeTypes;

import javax.activation.MimetypesFileTypeMap;
import java.lang.reflect.Array;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.Map;
import java.util.Set;

public class ActivationBackedMimeTypes implements MimeTypes {

    private static final MimetypesFileTypeMap MIME_TYPES_MAP = new MimetypesFileTypeMap();

    @Override
    public String getContentType(String name) {
        return MIME_TYPES_MAP.getContentType(name);
    }

    private static Set<String> extractKnownMimeTypes() {
        try {
            Function<Object, String> getMimeTypeFunction = new GetMimeTypeFunction();
            Field typeHashField = makeFieldAccessible(Class.forName("com.sun.activation.registries.MimeTypeFile"),
                    "type_hash");
            Field mimeTypeFilesField = makeFieldAccessible(MimetypesFileTypeMap.class, "DB");
            Object mimeTypeFiles = mimeTypeFilesField.get(MIME_TYPES_MAP);
            Set<String> mimeTypes = Sets.newHashSet();
            for (int i = 0; i < Array.getLength(mimeTypeFiles); i++) {
                Object mimeTypeFile = Array.get(mimeTypeFiles, i);
                if (mimeTypeFile != null) {
                    Map<?, ?> typeHash = (Map) typeHashField.get(mimeTypeFile);
                    Iterables.addAll(mimeTypes, Iterables.transform(typeHash.values(), getMimeTypeFunction));
                }
            }
            return ImmutableSet.copyOf(mimeTypes);
        } catch (ReflectiveOperationException | NullPointerException ex) {
            return ImmutableSet.of();
        }
    }

    private static Field makeFieldAccessible(Class<?> clazz, String fieldName) throws ReflectiveOperationException {
        Field field = clazz.getDeclaredField(fieldName);
        field.setAccessible(true);
        return field;
    }

    private static class GetMimeTypeFunction implements Function<Object, String> {
        private final Method getMIMEType;

        GetMimeTypeFunction() throws ReflectiveOperationException {
            this.getMIMEType = Class.forName("com.sun.activation.registries.MimeTypeEntry")
                    .getMethod("getMIMEType");
        }

        @Override
        public String apply(Object entry) {
            try {
                return (String) getMIMEType.invoke(entry);
            } catch (ReflectiveOperationException ex) {
                throw new NullPointerException("Could not get mime type: " + ex.getMessage());
            }
        }
    }

    public static ImmutableSet<String> getDefaultExcludedMimeTypes() {
        Set<String> knownMimeTypes = extractKnownMimeTypes();

        Set<String> compressedArchiveTypes = ImmutableSet.of("application/compress", "application/zip",
                "application/gzip");
        Iterable<String> knownExceptNonXmlImagesAudioAndVideo = Iterables.filter(knownMimeTypes,
                type -> (type.startsWith("image/") || type.startsWith("audio/") || type.startsWith("video/"))
                        && !type.endsWith("+xml"));

        return ImmutableSet.<String>builder().addAll(compressedArchiveTypes)
                .addAll(knownExceptNonXmlImagesAudioAndVideo).build();
    }

}