spring MimeTypeUtils 源码
spring MimeTypeUtils 代码
文件路径：/spring-core/src/main/java/org/springframework/util/MimeTypeUtils.java
/*
* Copyright 2002-2020 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
*
* https://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 org.springframework.util;
import java.nio.charset.StandardCharsets;
import java.nio.charset.UnsupportedCharsetException;
import java.security.SecureRandom;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Random;
import java.util.function.BiPredicate;
import java.util.stream.Collectors;
import org.springframework.lang.Nullable;
/**
* Miscellaneous {@link MimeType} utility methods.
*
* @author Arjen Poutsma
* @author Rossen Stoyanchev
* @author Dimitrios Liapis
* @author Brian Clozel
* @author Sam Brannen
* @since 4.0
*/
public abstract class MimeTypeUtils {
private static final byte[] BOUNDARY_CHARS =
new byte[] {'-', '_', '1', '2', '3', '4', '5', '6', '7', '8', '9', '0', 'a', 'b', 'c', 'd', 'e', 'f', 'g',
'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'A',
'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U',
'V', 'W', 'X', 'Y', 'Z'};
/**
* Comparator formally used by {@link #sortBySpecificity(List)}.
* @deprecated As of 6.0, with no direct replacement
*/
@Deprecated
public static final Comparator<MimeType> SPECIFICITY_COMPARATOR = new MimeType.SpecificityComparator<>();
/**
* Public constant mime type that includes all media ranges (i.e. "*/*").
*/
public static final MimeType ALL;
/**
* A String equivalent of {@link MimeTypeUtils#ALL}.
*/
public static final String ALL_VALUE = "*/*";
/**
* Public constant mime type for {@code application/graphql+json}.
* @since 5.3.19
* @see <a href="https://github.com/graphql/graphql-over-http">GraphQL over HTTP spec</a>
*/
public static final MimeType APPLICATION_GRAPHQL;
/**
* A String equivalent of {@link MimeTypeUtils#APPLICATION_GRAPHQL}.
* @since 5.3.19
*/
public static final String APPLICATION_GRAPHQL_VALUE = "application/graphql+json";
/**
* Public constant mime type for {@code application/json}.
*/
public static final MimeType APPLICATION_JSON;
/**
* A String equivalent of {@link MimeTypeUtils#APPLICATION_JSON}.
*/
public static final String APPLICATION_JSON_VALUE = "application/json";
/**
* Public constant mime type for {@code application/octet-stream}.
* */
public static final MimeType APPLICATION_OCTET_STREAM;
/**
* A String equivalent of {@link MimeTypeUtils#APPLICATION_OCTET_STREAM}.
*/
public static final String APPLICATION_OCTET_STREAM_VALUE = "application/octet-stream";
/**
* Public constant mime type for {@code application/xml}.
*/
public static final MimeType APPLICATION_XML;
/**
* A String equivalent of {@link MimeTypeUtils#APPLICATION_XML}.
*/
public static final String APPLICATION_XML_VALUE = "application/xml";
/**
* Public constant mime type for {@code image/gif}.
*/
public static final MimeType IMAGE_GIF;
/**
* A String equivalent of {@link MimeTypeUtils#IMAGE_GIF}.
*/
public static final String IMAGE_GIF_VALUE = "image/gif";
/**
* Public constant mime type for {@code image/jpeg}.
*/
public static final MimeType IMAGE_JPEG;
/**
* A String equivalent of {@link MimeTypeUtils#IMAGE_JPEG}.
*/
public static final String IMAGE_JPEG_VALUE = "image/jpeg";
/**
* Public constant mime type for {@code image/png}.
*/
public static final MimeType IMAGE_PNG;
/**
* A String equivalent of {@link MimeTypeUtils#IMAGE_PNG}.
*/
public static final String IMAGE_PNG_VALUE = "image/png";
/**
* Public constant mime type for {@code text/html}.
* */
public static final MimeType TEXT_HTML;
/**
* A String equivalent of {@link MimeTypeUtils#TEXT_HTML}.
*/
public static final String TEXT_HTML_VALUE = "text/html";
/**
* Public constant mime type for {@code text/plain}.
* */
public static final MimeType TEXT_PLAIN;
/**
* A String equivalent of {@link MimeTypeUtils#TEXT_PLAIN}.
*/
public static final String TEXT_PLAIN_VALUE = "text/plain";
/**
* Public constant mime type for {@code text/xml}.
* */
public static final MimeType TEXT_XML;
/**
* A String equivalent of {@link MimeTypeUtils#TEXT_XML}.
*/
public static final String TEXT_XML_VALUE = "text/xml";
private static final ConcurrentLruCache<String, MimeType> cachedMimeTypes =
new ConcurrentLruCache<>(64, MimeTypeUtils::parseMimeTypeInternal);
@Nullable
private static volatile Random random;
static {
// Not using "parseMimeType" to avoid static init cost
ALL = new MimeType("*", "*");
APPLICATION_GRAPHQL = new MimeType("application", "graphql+json");
APPLICATION_JSON = new MimeType("application", "json");
APPLICATION_OCTET_STREAM = new MimeType("application", "octet-stream");
APPLICATION_XML = new MimeType("application", "xml");
IMAGE_GIF = new MimeType("image", "gif");
IMAGE_JPEG = new MimeType("image", "jpeg");
IMAGE_PNG = new MimeType("image", "png");
TEXT_HTML = new MimeType("text", "html");
TEXT_PLAIN = new MimeType("text", "plain");
TEXT_XML = new MimeType("text", "xml");
}
/**
* Parse the given String into a single {@code MimeType}.
* Recently parsed {@code MimeType} are cached for further retrieval.
* @param mimeType the string to parse
* @return the mime type
* @throws InvalidMimeTypeException if the string cannot be parsed
*/
public static MimeType parseMimeType(String mimeType) {
if (!StringUtils.hasLength(mimeType)) {
throw new InvalidMimeTypeException(mimeType, "'mimeType' must not be empty");
}
// do not cache multipart mime types with random boundaries
if (mimeType.startsWith("multipart")) {
return parseMimeTypeInternal(mimeType);
}
return cachedMimeTypes.get(mimeType);
}
private static MimeType parseMimeTypeInternal(String mimeType) {
int index = mimeType.indexOf(';');
String fullType = (index >= 0 ? mimeType.substring(0, index) : mimeType).trim();
if (fullType.isEmpty()) {
throw new InvalidMimeTypeException(mimeType, "'mimeType' must not be empty");
}
// java.net.HttpURLConnection returns a *; q=.2 Accept header
if (MimeType.WILDCARD_TYPE.equals(fullType)) {
fullType = "*/*";
}
int subIndex = fullType.indexOf('/');
if (subIndex == -1) {
throw new InvalidMimeTypeException(mimeType, "does not contain '/'");
}
if (subIndex == fullType.length() - 1) {
throw new InvalidMimeTypeException(mimeType, "does not contain subtype after '/'");
}
String type = fullType.substring(0, subIndex);
String subtype = fullType.substring(subIndex + 1);
if (MimeType.WILDCARD_TYPE.equals(type) && !MimeType.WILDCARD_TYPE.equals(subtype)) {
throw new InvalidMimeTypeException(mimeType, "wildcard type is legal only in '*/*' (all mime types)");
}
Map<String, String> parameters = null;
do {
int nextIndex = index + 1;
boolean quoted = false;
while (nextIndex < mimeType.length()) {
char ch = mimeType.charAt(nextIndex);
if (ch == ';') {
if (!quoted) {
break;
}
}
else if (ch == '"') {
quoted = !quoted;
}
nextIndex++;
}
String parameter = mimeType.substring(index + 1, nextIndex).trim();
if (parameter.length() > 0) {
if (parameters == null) {
parameters = new LinkedHashMap<>(4);
}
int eqIndex = parameter.indexOf('=');
if (eqIndex >= 0) {
String attribute = parameter.substring(0, eqIndex).trim();
String value = parameter.substring(eqIndex + 1).trim();
parameters.put(attribute, value);
}
}
index = nextIndex;
}
while (index < mimeType.length());
try {
return new MimeType(type, subtype, parameters);
}
catch (UnsupportedCharsetException ex) {
throw new InvalidMimeTypeException(mimeType, "unsupported charset '" + ex.getCharsetName() + "'");
}
catch (IllegalArgumentException ex) {
throw new InvalidMimeTypeException(mimeType, ex.getMessage());
}
}
/**
* Parse the comma-separated string into a list of {@code MimeType} objects.
* @param mimeTypes the string to parse
* @return the list of mime types
* @throws InvalidMimeTypeException if the string cannot be parsed
*/
public static List<MimeType> parseMimeTypes(String mimeTypes) {
if (!StringUtils.hasLength(mimeTypes)) {
return Collections.emptyList();
}
return tokenize(mimeTypes).stream()
.filter(StringUtils::hasText)
.map(MimeTypeUtils::parseMimeType)
.collect(Collectors.toList());
}
/**
* Tokenize the given comma-separated string of {@code MimeType} objects
* into a {@code List<String>}. Unlike simple tokenization by ",", this
* method takes into account quoted parameters.
* @param mimeTypes the string to tokenize
* @return the list of tokens
* @since 5.1.3
*/
public static List<String> tokenize(String mimeTypes) {
if (!StringUtils.hasLength(mimeTypes)) {
return Collections.emptyList();
}
List<String> tokens = new ArrayList<>();
boolean inQuotes = false;
int startIndex = 0;
int i = 0;
while (i < mimeTypes.length()) {
switch (mimeTypes.charAt(i)) {
case '"':
inQuotes = !inQuotes;
break;
case ',':
if (!inQuotes) {
tokens.add(mimeTypes.substring(startIndex, i));
startIndex = i + 1;
}
break;
case '\\':
i++;
break;
}
i++;
}
tokens.add(mimeTypes.substring(startIndex));
return tokens;
}
/**
* Return a string representation of the given list of {@code MimeType} objects.
* @param mimeTypes the string to parse
* @return the list of mime types
* @throws IllegalArgumentException if the String cannot be parsed
*/
public static String toString(Collection<? extends MimeType> mimeTypes) {
StringBuilder builder = new StringBuilder();
for (Iterator<? extends MimeType> iterator = mimeTypes.iterator(); iterator.hasNext();) {
MimeType mimeType = iterator.next();
mimeType.appendTo(builder);
if (iterator.hasNext()) {
builder.append(", ");
}
}
return builder.toString();
}
/**
* Sorts the given list of {@code MimeType} objects by
* {@linkplain MimeType#isMoreSpecific(MimeType) specificity}.
*
* <p>Because of the computational cost, this method throws an exception
* when the given list contains too many elements.
* @param mimeTypes the list of mime types to be sorted
* @throws IllegalArgumentException if {@code mimeTypes} contains more
* than 50 elements
* @see <a href="https://tools.ietf.org/html/rfc7231#section-5.3.2">HTTP 1.1: Semantics
* and Content, section 5.3.2</a>
* @see MimeType#isMoreSpecific(MimeType)
*/
public static <T extends MimeType> void sortBySpecificity(List<T> mimeTypes) {
Assert.notNull(mimeTypes, "'mimeTypes' must not be null");
Assert.isTrue(mimeTypes.size() <= 50, "Too many elements");
bubbleSort(mimeTypes, MimeType::isLessSpecific);
}
static <T> void bubbleSort(List<T> list, BiPredicate<? super T, ? super T> swap) {
int len = list.size();
for (int i = 0; i < len; i++) {
for (int j = 1; j < len - i ; j++) {
T prev = list.get(j - 1);
T cur = list.get(j);
if (swap.test(prev, cur)) {
list.set(j, prev);
list.set(j - 1, cur);
}
}
}
}
/**
* Generate a random MIME boundary as bytes, often used in multipart mime types.
*/
public static byte[] generateMultipartBoundary() {
Random randomToUse = initRandom();
byte[] boundary = new byte[randomToUse.nextInt(11) + 30];
for (int i = 0; i < boundary.length; i++) {
boundary[i] = BOUNDARY_CHARS[randomToUse.nextInt(BOUNDARY_CHARS.length)];
}
return boundary;
}
/**
* Lazily initialize the {@link SecureRandom} for {@link #generateMultipartBoundary()}.
*/
private static Random initRandom() {
Random randomToUse = random;
if (randomToUse == null) {
synchronized (MimeTypeUtils.class) {
randomToUse = random;
if (randomToUse == null) {
randomToUse = new SecureRandom();
random = randomToUse;
}
}
}
return randomToUse;
}
/**
* Generate a random MIME boundary as String, often used in multipart mime types.
*/
public static String generateMultipartBoundaryString() {
return new String(generateMultipartBoundary(), StandardCharsets.US_ASCII);
}
}
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