com.proofpoint.http.client.MediaType.java Source code

Java tutorial

Introduction

Here is the source code for com.proofpoint.http.client.MediaType.java

Source

/*
 * Copyright (C) 2011 The Guava 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 com.proofpoint.http.client;

import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtCompatible;
import com.google.common.base.Ascii;
import com.google.common.base.CharMatcher;
import com.google.common.base.Function;
import com.google.common.base.Joiner;
import com.google.common.base.Joiner.MapJoiner;
import com.google.common.base.Objects;
import com.google.common.base.Optional;
import com.google.common.collect.ImmutableListMultimap;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableMultiset;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;
import com.google.common.collect.Maps;
import com.google.common.collect.Multimap;
import com.google.common.collect.Multimaps;

import javax.annotation.Nullable;
import javax.annotation.concurrent.Immutable;
import java.nio.charset.Charset;
import java.nio.charset.IllegalCharsetNameException;
import java.nio.charset.UnsupportedCharsetException;
import java.util.Collection;
import java.util.Map;
import java.util.Map.Entry;

import static com.google.common.base.CharMatcher.ASCII;
import static com.google.common.base.CharMatcher.JAVA_ISO_CONTROL;
import static com.google.common.base.Charsets.UTF_8;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;

//
// todo drop this when Guava 12 is released
//
/**
 * Represents an <a href="http://en.wikipedia.org/wiki/Internet_media_type">Internet Media Type</a>
 * (also known as a MIME Type or Content Type). This class also supports the concept of media ranges
 * <a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.1">defined by HTTP/1.1</a>.
 * As such, the {@code *} character is treated as a wildcard and is used to represent any acceptable
 * type or subtype value. A media type may not have wildcard type with a declared subtype. The
 * {@code *} character has no special meaning as part of a parameter. All values for type, subtype,
 * parameter attributes or parameter values must be valid according to RFCs
 * <a href="http://www.ietf.org/rfc/rfc2045.txt">2045</a> and
 * <a href="http://www.ietf.org/rfc/rfc2046.txt">2046</a>.
 * <p/>
 * <p>All portions of the media type that are case-insensitive (type, subtype, parameter attributes)
 * are normalized to lowercase. The value of the {@code charset} parameter is normalized to
 * lowercase, but all others are left as-is.
 * <p/>
 * <p>Note that this specifically does <strong>not</strong> represent the value of the MIME
 * {@code Content-Type} header and as such has no support for header-specific considerations such as
 * line folding and comments.
 * <p/>
 * <p>For media types that take a charset the predefined constants default to UTF-8 and have a
 * "_UTF_8" suffix. To get a version without a character set, use {@link #withoutParameters}.
 *
 * @author Gregory Kick
 * @since 12.0
 */
@Beta
@GwtCompatible
@Immutable
final class MediaType {
    private static final String CHARSET_ATTRIBUTE = "charset";
    private static final ImmutableListMultimap<String, String> UTF_8_CONSTANT_PARAMETERS = ImmutableListMultimap
            .of(CHARSET_ATTRIBUTE, Ascii.toLowerCase(UTF_8.name()));

    /**
     * Matcher for type, subtype and attributes.
     */
    private static final CharMatcher TOKEN_MATCHER = ASCII.and(JAVA_ISO_CONTROL.negate())
            .and(CharMatcher.isNot(' ')).and(CharMatcher.noneOf("()<>@,;:\\\"/[]?="));
    private static final CharMatcher QUOTED_TEXT_MATCHER = ASCII.and(CharMatcher.noneOf("\"\\\r"));
    /*
    * This matches the same characters as linear-white-space from RFC 822, but we make no effort to
    * enforce any particular rules with regards to line folding as stated in the class docs.
    */
    private static final CharMatcher LINEAR_WHITE_SPACE = CharMatcher.anyOf(" \t\r\n");

    // TODO(gak): make these public?
    private static final String APPLICATION_TYPE = "application";
    private static final String AUDIO_TYPE = "audio";
    private static final String IMAGE_TYPE = "image";
    private static final String TEXT_TYPE = "text";
    private static final String VIDEO_TYPE = "video";

    private static final String WILDCARD = "*";

    /*
    * The following constants are grouped by their type and ordered alphabetically by the constant
    * name within that type. The constant name should be a sensible identifier that is closest to the
    * "common name" of the media.  This is often, but not necessarily the same as the subtype.
    *
    * Be sure to declare all constants with the type and subtype in all lowercase.
    *
    * When adding constants, be sure to add an entry into the KNOWN_TYPES map. For types that
    * take a charset (e.g. all text/* types), default to UTF-8 and suffix with "_UTF_8".
    */

    public static final MediaType ANY_TYPE = createConstant(WILDCARD, WILDCARD);
    public static final MediaType ANY_TEXT_TYPE = createConstant(TEXT_TYPE, WILDCARD);
    public static final MediaType ANY_IMAGE_TYPE = createConstant(IMAGE_TYPE, WILDCARD);
    public static final MediaType ANY_AUDIO_TYPE = createConstant(AUDIO_TYPE, WILDCARD);
    public static final MediaType ANY_VIDEO_TYPE = createConstant(VIDEO_TYPE, WILDCARD);
    public static final MediaType ANY_APPLICATION_TYPE = createConstant(APPLICATION_TYPE, WILDCARD);

    /* text types */
    public static final MediaType CACHE_MANIFEST_UTF_8 = createConstantUtf8(TEXT_TYPE, "cache-manifest");
    public static final MediaType CSS_UTF_8 = createConstantUtf8(TEXT_TYPE, "css");
    public static final MediaType CSV_UTF_8 = createConstantUtf8(TEXT_TYPE, "csv");
    public static final MediaType HTML_UTF_8 = createConstantUtf8(TEXT_TYPE, "html");
    public static final MediaType I_CALENDAR_UTF_8 = createConstantUtf8(TEXT_TYPE, "calendar");
    public static final MediaType PLAIN_TEXT_UTF_8 = createConstantUtf8(TEXT_TYPE, "plain");
    /**
     * <a href="http://www.rfc-editor.org/rfc/rfc4329.txt">RFC 4329</a> declares
     * {link #JAVASCRIPT application/javascript} to be the correct media type for JavaScript, but this
     * may be necessary in certain situations for compatibility.
     */
    public static final MediaType TEXT_JAVASCRIPT_UTF_8 = createConstantUtf8(TEXT_TYPE, "javascript");
    public static final MediaType VCARD_UTF_8 = createConstantUtf8(TEXT_TYPE, "vcard");
    public static final MediaType XML_UTF_8 = createConstantUtf8(TEXT_TYPE, "xml");

    /* image types */
    public static final MediaType GIF = createConstant(IMAGE_TYPE, "gif");
    public static final MediaType ICO = createConstant(IMAGE_TYPE, "vnd.microsoft.icon");
    public static final MediaType JPEG = createConstant(IMAGE_TYPE, "jpeg");
    public static final MediaType PNG = createConstant(IMAGE_TYPE, "png");
    public static final MediaType SVG_UTF_8 = createConstantUtf8(IMAGE_TYPE, "svg+xml");
    public static final MediaType TIFF = createConstant(IMAGE_TYPE, "tiff");

    /* audio types */
    public static final MediaType MP4_AUDIO = createConstant(AUDIO_TYPE, "mp4");
    public static final MediaType MPEG_AUDIO = createConstant(AUDIO_TYPE, "mpeg");
    public static final MediaType OGG_AUDIO = createConstant(AUDIO_TYPE, "ogg");
    public static final MediaType WEBM_AUDIO = createConstant(AUDIO_TYPE, "webm");

    /* video types */
    public static final MediaType MP4_VIDEO = createConstant(VIDEO_TYPE, "mp4");
    public static final MediaType MPEG_VIDEO = createConstant(VIDEO_TYPE, "mpeg");
    public static final MediaType OGG_VIDEO = createConstant(VIDEO_TYPE, "ogg");
    public static final MediaType QUICKTIME = createConstant(VIDEO_TYPE, "quicktime");
    public static final MediaType WEBM_VIDEO = createConstant(VIDEO_TYPE, "webm");
    public static final MediaType WMV = createConstant(VIDEO_TYPE, "x-ms-wmv");

    /* application types */
    public static final MediaType ATOM_UTF_8 = createConstantUtf8(APPLICATION_TYPE, "atom+xml");
    public static final MediaType BZIP2 = createConstant(APPLICATION_TYPE, "x-bzip2");
    public static final MediaType FORM_DATA = createConstant(APPLICATION_TYPE, "x-www-form-urlencoded");
    public static final MediaType GZIP = createConstant(APPLICATION_TYPE, "x-gzip");
    /**
     * <a href="http://www.rfc-editor.org/rfc/rfc4329.txt">RFC 4329</a> declares this to be the
     * correct media type for JavaScript, but {@link #TEXT_JAVASCRIPT_UTF_8 text/javascript} may be
     * necessary in certain situations for compatibility.
     */
    public static final MediaType JAVASCRIPT_UTF_8 = createConstantUtf8(APPLICATION_TYPE, "javascript");
    public static final MediaType JSON_UTF_8 = createConstantUtf8(APPLICATION_TYPE, "json");
    public static final MediaType KML = createConstant(APPLICATION_TYPE, "vnd.google-earth.kml+xml");
    public static final MediaType KMZ = createConstant(APPLICATION_TYPE, "vnd.google-earth.kmz");
    public static final MediaType MICROSOFT_EXCEL = createConstant(APPLICATION_TYPE, "vnd.ms-excel");
    public static final MediaType MICROSOFT_POWERPOINT = createConstant(APPLICATION_TYPE, "vnd.ms-powerpoint");
    public static final MediaType MICROSOFT_WORD = createConstant(APPLICATION_TYPE, "msword");
    public static final MediaType OCTET_STREAM = createConstant(APPLICATION_TYPE, "octet-stream");
    public static final MediaType OGG_CONTAINER = createConstant(APPLICATION_TYPE, "ogg");
    public static final MediaType OOXML_DOCUMENT = createConstant(APPLICATION_TYPE,
            "vnd.openxmlformats-officedocument.wordprocessingml.document");
    public static final MediaType OOXML_PRESENTATION = createConstant(APPLICATION_TYPE,
            "vnd.openxmlformats-officedocument.presentationml.presentation");
    public static final MediaType OOXML_SHEET = createConstant(APPLICATION_TYPE,
            "vnd.openxmlformats-officedocument.spreadsheetml.sheet");
    public static final MediaType OPENDOCUMENT_GRAPHICS = createConstant(APPLICATION_TYPE,
            "vnd.oasis.opendocument.graphics");
    public static final MediaType OPENDOCUMENT_PRESENTATION = createConstant(APPLICATION_TYPE,
            "vnd.oasis.opendocument.presentation");
    public static final MediaType OPENDOCUMENT_SPREADSHEET = createConstant(APPLICATION_TYPE,
            "vnd.oasis.opendocument.spreadsheet");
    public static final MediaType OPENDOCUMENT_TEXT = createConstant(APPLICATION_TYPE,
            "vnd.oasis.opendocument.text");
    public static final MediaType PDF = createConstant(APPLICATION_TYPE, "pdf");
    public static final MediaType POSTSCRIPT = createConstant(APPLICATION_TYPE, "postscript");
    public static final MediaType RTF_UTF_8 = createConstantUtf8(APPLICATION_TYPE, "rtf");
    public static final MediaType SHOCKWAVE_FLASH = createConstant(APPLICATION_TYPE, "x-shockwave-flash");
    public static final MediaType TAR = createConstant(APPLICATION_TYPE, "x-tar");
    public static final MediaType XHTML_UTF_8 = createConstantUtf8(APPLICATION_TYPE, "xhtml+xml");
    public static final MediaType ZIP = createConstant(APPLICATION_TYPE, "zip");

    private static final ImmutableMap<MediaType, MediaType> KNOWN_TYPES = new ImmutableMap.Builder<MediaType, MediaType>()
            .put(ANY_TYPE, ANY_TYPE).put(ANY_TEXT_TYPE, ANY_TEXT_TYPE).put(ANY_IMAGE_TYPE, ANY_IMAGE_TYPE)
            .put(ANY_AUDIO_TYPE, ANY_AUDIO_TYPE).put(ANY_VIDEO_TYPE, ANY_VIDEO_TYPE)
            .put(ANY_APPLICATION_TYPE, ANY_APPLICATION_TYPE)
            /* text types */
            .put(CACHE_MANIFEST_UTF_8, CACHE_MANIFEST_UTF_8).put(CSS_UTF_8, CSS_UTF_8).put(CSV_UTF_8, CSV_UTF_8)
            .put(HTML_UTF_8, HTML_UTF_8).put(I_CALENDAR_UTF_8, I_CALENDAR_UTF_8)
            .put(PLAIN_TEXT_UTF_8, PLAIN_TEXT_UTF_8).put(TEXT_JAVASCRIPT_UTF_8, TEXT_JAVASCRIPT_UTF_8)
            .put(VCARD_UTF_8, VCARD_UTF_8).put(XML_UTF_8, XML_UTF_8)
            /* image types */
            .put(GIF, GIF).put(ICO, ICO).put(JPEG, JPEG).put(PNG, PNG).put(SVG_UTF_8, SVG_UTF_8).put(TIFF, TIFF)
            /* audio types */
            .put(MP4_AUDIO, MP4_AUDIO).put(MPEG_AUDIO, MPEG_AUDIO).put(OGG_AUDIO, OGG_AUDIO)
            .put(WEBM_AUDIO, WEBM_AUDIO)
            /* video types */
            .put(MP4_VIDEO, MP4_VIDEO).put(MPEG_VIDEO, MPEG_VIDEO).put(OGG_VIDEO, OGG_VIDEO)
            .put(QUICKTIME, QUICKTIME).put(WEBM_VIDEO, WEBM_VIDEO).put(WMV, WMV)
            /* application types */
            .put(ATOM_UTF_8, ATOM_UTF_8).put(BZIP2, BZIP2).put(FORM_DATA, FORM_DATA).put(GZIP, GZIP)
            .put(JAVASCRIPT_UTF_8, JAVASCRIPT_UTF_8).put(JSON_UTF_8, JSON_UTF_8).put(KML, KML).put(KMZ, KMZ)
            .put(MICROSOFT_EXCEL, MICROSOFT_EXCEL).put(MICROSOFT_POWERPOINT, MICROSOFT_POWERPOINT)
            .put(MICROSOFT_WORD, MICROSOFT_WORD).put(OCTET_STREAM, OCTET_STREAM).put(OGG_CONTAINER, OGG_CONTAINER)
            .put(OOXML_DOCUMENT, OOXML_DOCUMENT).put(OOXML_PRESENTATION, OOXML_PRESENTATION)
            .put(OOXML_SHEET, OOXML_SHEET).put(OPENDOCUMENT_GRAPHICS, OPENDOCUMENT_GRAPHICS)
            .put(OPENDOCUMENT_PRESENTATION, OPENDOCUMENT_PRESENTATION)
            .put(OPENDOCUMENT_SPREADSHEET, OPENDOCUMENT_SPREADSHEET).put(OPENDOCUMENT_TEXT, OPENDOCUMENT_TEXT)
            .put(PDF, PDF).put(POSTSCRIPT, POSTSCRIPT).put(RTF_UTF_8, RTF_UTF_8)
            .put(SHOCKWAVE_FLASH, SHOCKWAVE_FLASH).put(TAR, TAR).put(XHTML_UTF_8, XHTML_UTF_8).put(ZIP, ZIP)
            .build();

    private final String type;
    private final String subtype;
    private final ImmutableListMultimap<String, String> parameters;

    private MediaType(String type, String subtype, ImmutableListMultimap<String, String> parameters) {
        this.type = type;
        this.subtype = subtype;
        this.parameters = parameters;
    }

    private static MediaType createConstant(String type, String subtype) {
        return new MediaType(type, subtype, ImmutableListMultimap.<String, String>of());
    }

    private static MediaType createConstantUtf8(String type, String subtype) {
        return new MediaType(type, subtype, UTF_8_CONSTANT_PARAMETERS);
    }

    /**
     * Returns the top-level media type.  For example, {@code "text"} in {@code "text/plain"}.
     */
    public String type() {
        return type;
    }

    /**
     * Returns the media subtype.  For example, {@code "plain"} in {@code "text/plain"}.
     */
    public String subtype() {
        return subtype;
    }

    /**
     * Returns a multimap containing the parameters of this media type.
     */
    public ImmutableListMultimap<String, String> parameters() {
        return parameters;
    }

    private Map<String, ImmutableMultiset<String>> parametersAsMap() {
        return Maps.transformValues(parameters.asMap(),
                new Function<Collection<String>, ImmutableMultiset<String>>() {
                    @Override
                    public ImmutableMultiset<String> apply(Collection<String> input) {
                        return ImmutableMultiset.copyOf(input);
                    }
                });
    }

    /**
     * Returns an optional charset for the value of the charset parameter if it is specified.
     *
     * @throws IllegalStateException if multiple charset values have been set for this media type
     * @throws IllegalCharsetNameException if a charset value is present, but illegal
     * @throws UnsupportedCharsetException if a charset value is present, but no support is available
     * in this instance of the Java virtual machine
     */
    public Optional<Charset> charset() {
        ImmutableSet<String> charsetValues = ImmutableSet.copyOf(parameters.get(CHARSET_ATTRIBUTE));
        switch (charsetValues.size()) {
        case 0:
            return Optional.absent();
        case 1:
            return Optional.of(Charset.forName(Iterables.getOnlyElement(charsetValues)));
        default:
            throw new IllegalStateException("Multiple charset values defined: " + charsetValues);
        }
    }

    /**
     * Returns a new instance with the same type and subtype as this instance, but without any
     * parameters.
     */
    public MediaType withoutParameters() {
        return parameters.isEmpty() ? this : create(type, subtype);
    }

    /**
     * <em>Replaces</em> all parameters with the given parameters.
     *
     * @throws IllegalArgumentException if any parameter or value is invalid
     */
    public MediaType withParameters(Multimap<String, String> parameters) {
        return create(type, subtype, parameters);
    }

    /**
     * <em>Replaces</em> all parameters with the given attribute with a single parameter with the
     * given value. If multiple parameters with the same attributes are necessary use
     * {@link #withParameters}. Prefer {@link #withCharset} for setting the {@code charset} parameter
     * when using a {@link Charset} object.
     *
     * @throws IllegalArgumentException if either {@code attribute} or {@code value} is invalid
     */
    public MediaType withParameter(String attribute, String value) {
        checkNotNull(attribute);
        checkNotNull(value);
        String normalizedAttribute = normalizeToken(attribute);
        ImmutableListMultimap.Builder<String, String> builder = ImmutableListMultimap.builder();
        for (Entry<String, String> entry : parameters.entries()) {
            String key = entry.getKey();
            if (!normalizedAttribute.equals(key)) {
                builder.put(key, entry.getValue());
            }
        }
        builder.put(normalizedAttribute, normalizeParameterValue(normalizedAttribute, value));
        MediaType mediaType = new MediaType(type, subtype, builder.build());
        // Return one of the constants if the media type is a known type.
        return Objects.firstNonNull(KNOWN_TYPES.get(mediaType), mediaType);
    }

    /**
     * Returns a new instance with the same type and subtype as this instance, with the
     * {@code charset} parameter set to the {@link Charset#name name} of the given charset. Only one
     * {@code charset} parameter will be present on the new instance regardless of the number set on
     * this one.
     * <p/>
     * <p>If a charset must be specified that is not supported on this JVM (and thus is not
     * representable as a {@link Charset} instance, use {@link #withParameter}.
     */
    public MediaType withCharset(Charset charset) {
        checkNotNull(charset);
        return withParameter(CHARSET_ATTRIBUTE, charset.name());
    }

    /**
     * Returns true if either the type or subtype is the wildcard.
     */
    public boolean hasWildcard() {
        return WILDCARD.equals(type) || WILDCARD.equals(subtype);
    }

    /**
     * Returns {@code true} if this instance falls within the range (as defined by
     * <a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html">the HTTP Accept header</a>)
     * given by the argument according to three criteria:
     * <p/>
     * <ol>
     * <li>The type of the argument is the wildcard or equal to the type of this instance.
     * <li>The subtype of the argument is the wildcard or equal to the subtype of this instance.
     * <li>All of the parameters present in the argument are present in this instance.
     * </ol>
     * <p/>
     * For example: <pre>   {@code
     *   PLAIN_TEXT_UTF_8.is(PLAIN_TEXT_UTF_8) // true
     *   PLAIN_TEXT_UTF_8.is(HTML_UTF_8) // false
     *   PLAIN_TEXT_UTF_8.is(ANY_TYPE) // true
     *   PLAIN_TEXT_UTF_8.is(ANY_TEXT_TYPE) // true
     *   PLAIN_TEXT_UTF_8.is(ANY_IMAGE_TYPE) // false
     *   PLAIN_TEXT_UTF_8.is(ANY_TEXT_TYPE.withCharset(UTF_8)) // true
     *   PLAIN_TEXT_UTF_8.withoutParameters().is(ANY_TEXT_TYPE.withCharset(UTF_8)) // false
     *   PLAIN_TEXT_UTF_8.is(ANY_TEXT_TYPE.withCharset(UTF_16)) // false}</pre>
     * <p/>
     * <p>Note that while it is possible to have the same parameter declared multiple times within a
     * media type this method does not consider the number of occurrences of a parameter.  For
     * example, {@code "text/plain; charset=UTF-8"} satisfies
     * {@code "text/plain; charset=UTF-8; charset=UTF-8"}.
     */
    public boolean is(MediaType mediaTypeRange) {
        return (mediaTypeRange.type.equals(WILDCARD) || mediaTypeRange.type.equals(this.type))
                && (mediaTypeRange.subtype.equals(WILDCARD) || mediaTypeRange.subtype.equals(this.subtype))
                && this.parameters.entries().containsAll(mediaTypeRange.parameters.entries());
    }

    /**
     * Creates a new media type with the given type and subtype.
     *
     * @throws IllegalArgumentException if type or subtype is invalid or if a wildcard is used for the
     * type, but not the subtype.
     */
    public static MediaType create(String type, String subtype) {
        return create(type, subtype, ImmutableListMultimap.<String, String>of());
    }

    /**
     * Creates a media type with the "application" type and the given subtype.
     *
     * @throws IllegalArgumentException if subtype is invalid
     */
    static MediaType createApplicationType(String subtype) {
        return create(APPLICATION_TYPE, subtype);
    }

    /**
     * Creates a media type with the "audio" type and the given subtype.
     *
     * @throws IllegalArgumentException if subtype is invalid
     */
    static MediaType createAudioType(String subtype) {
        return create(AUDIO_TYPE, subtype);
    }

    /**
     * Creates a media type with the "image" type and the given subtype.
     *
     * @throws IllegalArgumentException if subtype is invalid
     */
    static MediaType createImageType(String subtype) {
        return create(IMAGE_TYPE, subtype);
    }

    /**
     * Creates a media type with the "text" type and the given subtype.
     *
     * @throws IllegalArgumentException if subtype is invalid
     */
    static MediaType createTextType(String subtype) {
        return create(TEXT_TYPE, subtype);
    }

    /**
     * Creates a media type with the "video" type and the given subtype.
     *
     * @throws IllegalArgumentException if subtype is invalid
     */
    static MediaType createVideoType(String subtype) {
        return create(VIDEO_TYPE, subtype);
    }

    private static MediaType create(String type, String subtype, Multimap<String, String> parameters) {
        checkNotNull(type);
        checkNotNull(subtype);
        checkNotNull(parameters);
        String normalizedType = normalizeToken(type);
        String normalizedSubtype = normalizeToken(subtype);
        checkArgument(!WILDCARD.equals(normalizedType) || WILDCARD.equals(normalizedSubtype),
                "A wildcard type cannot be used with a non-wildcard subtype");
        ImmutableListMultimap.Builder<String, String> builder = ImmutableListMultimap.builder();
        for (Entry<String, String> entry : parameters.entries()) {
            String attribute = normalizeToken(entry.getKey());
            builder.put(attribute, normalizeParameterValue(attribute, entry.getValue()));
        }
        MediaType mediaType = new MediaType(normalizedType, normalizedSubtype, builder.build());
        // Return one of the constants if the media type is a known type.
        return Objects.firstNonNull(KNOWN_TYPES.get(mediaType), mediaType);
    }

    private static String normalizeToken(String token) {
        checkArgument(TOKEN_MATCHER.matchesAllOf(token));
        return Ascii.toLowerCase(token);
    }

    private static String normalizeParameterValue(String attribute, String value) {
        return CHARSET_ATTRIBUTE.equals(attribute) ? Ascii.toLowerCase(value) : value;
    }

    /**
     * Parses a media type from its string representation.
     *
     * @throws IllegalArgumentException if the input is not parsable
     */
    public static MediaType parse(String input) {
        checkNotNull(input);
        Tokenizer tokenizer = new Tokenizer(input);
        try {
            String type = tokenizer.consumeToken(TOKEN_MATCHER);
            tokenizer.consumeCharacter('/');
            String subtype = tokenizer.consumeToken(TOKEN_MATCHER);
            ImmutableListMultimap.Builder<String, String> parameters = ImmutableListMultimap.builder();
            while (tokenizer.hasMore()) {
                tokenizer.consumeCharacter(';');
                tokenizer.consumeToken(LINEAR_WHITE_SPACE);
                String attribute = tokenizer.consumeToken(TOKEN_MATCHER);
                tokenizer.consumeCharacter('=');
                final String value;
                if ('"' == tokenizer.previewChar()) {
                    tokenizer.consumeCharacter('"');
                    StringBuilder valueBuilder = new StringBuilder();
                    while ('"' != tokenizer.previewChar()) {
                        if ('\\' == tokenizer.previewChar()) {
                            tokenizer.consumeCharacter('\\');
                            valueBuilder.append(tokenizer.consumeCharacter(ASCII));
                        } else {
                            valueBuilder.append(tokenizer.consumeToken(QUOTED_TEXT_MATCHER));
                        }
                    }
                    value = valueBuilder.toString();
                    tokenizer.consumeCharacter('"');
                } else {
                    value = tokenizer.consumeToken(TOKEN_MATCHER);
                }
                parameters.put(attribute, value);
            }
            return create(type, subtype, parameters.build());
        } catch (IllegalStateException e) {
            throw new IllegalArgumentException(e);
        }
    }

    private static final class Tokenizer {
        final String input;
        int position = 0;

        Tokenizer(String input) {
            this.input = input;
        }

        String consumeToken(CharMatcher matcher) {
            checkState(hasMore());
            int startPosition = position;
            position = matcher.negate().indexIn(input, startPosition);
            checkState(position != startPosition);
            return hasMore() ? input.substring(startPosition, position) : input.substring(startPosition);
        }

        char consumeCharacter(CharMatcher matcher) {
            checkState(hasMore());
            char c = previewChar();
            checkState(matcher.matches(c));
            position++;
            return c;
        }

        char consumeCharacter(char c) {
            checkState(hasMore());
            checkState(previewChar() == c);
            position++;
            return c;
        }

        char previewChar() {
            checkState(hasMore());
            return input.charAt(position);
        }

        boolean hasMore() {
            return (position >= 0) && (position < input.length());
        }
    }

    @Override
    public boolean equals(@Nullable Object obj) {
        if (obj == this) {
            return true;
        } else if (obj instanceof MediaType) {
            MediaType that = (MediaType) obj;
            return this.type.equals(that.type) && this.subtype.equals(that.subtype)
            // compare parameters regardless of order
                    && this.parametersAsMap().equals(that.parametersAsMap());
        } else {
            return false;
        }
    }

    @Override
    public int hashCode() {
        return Objects.hashCode(type, subtype, parametersAsMap());
    }

    private static final MapJoiner PARAMETER_JOINER = Joiner.on("; ").withKeyValueSeparator("=");

    /**
     * Returns the string representation of this media type in the format described in <a
     * href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>.
     */
    @Override
    public String toString() {
        StringBuilder builder = new StringBuilder().append(type).append('/').append(subtype);
        if (!parameters.isEmpty()) {
            builder.append("; ");
            Multimap<String, String> quotedParameters = Multimaps.transformValues(parameters,
                    new Function<String, String>() {
                        @Override
                        public String apply(String value) {
                            return TOKEN_MATCHER.matchesAllOf(value) ? value : escapeAndQuote(value);
                        }
                    });
            PARAMETER_JOINER.appendTo(builder, quotedParameters.entries());
        }
        return builder.toString();
    }

    private static String escapeAndQuote(String value) {
        StringBuilder escaped = new StringBuilder(value.length() + 16).append('"');
        for (char ch : value.toCharArray()) {
            if (ch == '\r' || ch == '\\' || ch == '"') {
                escaped.append('\\');
            }
            escaped.append(ch);
        }
        return escaped.append('"').toString();
    }
}