org.springframework.core.codec.AbstractCharSequenceDecoder Maven / Gradle / Ivy
/*
* Copyright 2002-2023 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.core.codec;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import org.reactivestreams.Publisher;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;
import org.springframework.core.ResolvableType;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.core.io.buffer.DataBufferUtils;
import org.springframework.core.io.buffer.LimitedDataBufferList;
import org.springframework.core.log.LogFormatUtils;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.MimeType;
/**
* Abstract base class that decodes from a data buffer stream to a
* {@code CharSequence} stream.
*
* @author Arjen Poutsma
* @since 6.1
* @param the character sequence type
*/
public abstract class AbstractCharSequenceDecoder extends AbstractDataBufferDecoder {
/** The default charset to use, i.e. "UTF-8". */
public static final Charset DEFAULT_CHARSET = StandardCharsets.UTF_8;
/** The default delimiter strings to use, i.e. {@code \r\n} and {@code \n}. */
public static final List DEFAULT_DELIMITERS = List.of("\r\n", "\n");
private final List delimiters;
private final boolean stripDelimiter;
private Charset defaultCharset = DEFAULT_CHARSET;
private final ConcurrentMap delimitersCache = new ConcurrentHashMap<>();
/**
* Create a new {@code AbstractCharSequenceDecoder} with the given parameters.
*/
protected AbstractCharSequenceDecoder(List delimiters, boolean stripDelimiter, MimeType... mimeTypes) {
super(mimeTypes);
Assert.notEmpty(delimiters, "'delimiters' must not be empty");
this.delimiters = new ArrayList<>(delimiters);
this.stripDelimiter = stripDelimiter;
}
/**
* Set the default character set to fall back on if the MimeType does not specify any.
* By default this is {@code UTF-8}.
* @param defaultCharset the charset to fall back on
*/
public void setDefaultCharset(Charset defaultCharset) {
this.defaultCharset = defaultCharset;
}
/**
* Return the configured {@link #setDefaultCharset(Charset) defaultCharset}.
*/
public Charset getDefaultCharset() {
return this.defaultCharset;
}
@Override
public final Flux decode(Publisher input, ResolvableType elementType,
@Nullable MimeType mimeType, @Nullable Map hints) {
byte[][] delimiterBytes = getDelimiterBytes(mimeType);
LimitedDataBufferList chunks = new LimitedDataBufferList(getMaxInMemorySize());
DataBufferUtils.Matcher matcher = DataBufferUtils.matcher(delimiterBytes);
return Flux.from(input)
.concatMapIterable(buffer -> processDataBuffer(buffer, matcher, chunks))
.concatWith(Mono.defer(() -> {
if (chunks.isEmpty()) {
return Mono.empty();
}
DataBuffer lastBuffer = chunks.get(0).factory().join(chunks);
chunks.clear();
return Mono.just(lastBuffer);
}))
.doFinally(signalType -> chunks.releaseAndClear())
.doOnDiscard(DataBuffer.class, DataBufferUtils::release)
.map(buffer -> decode(buffer, elementType, mimeType, hints));
}
private byte[][] getDelimiterBytes(@Nullable MimeType mimeType) {
return this.delimitersCache.computeIfAbsent(getCharset(mimeType), charset -> {
byte[][] result = new byte[this.delimiters.size()][];
for (int i = 0; i < this.delimiters.size(); i++) {
result[i] = this.delimiters.get(i).getBytes(charset);
}
return result;
});
}
private Collection processDataBuffer(DataBuffer buffer, DataBufferUtils.Matcher matcher,
LimitedDataBufferList chunks) {
boolean release = true;
try {
List result = null;
do {
int endIndex = matcher.match(buffer);
if (endIndex == -1) {
chunks.add(buffer);
release = false;
break;
}
DataBuffer split = buffer.split(endIndex + 1);
if (result == null) {
result = new ArrayList<>();
}
int delimiterLength = matcher.delimiter().length;
if (chunks.isEmpty()) {
if (this.stripDelimiter) {
split.writePosition(split.writePosition() - delimiterLength);
}
result.add(split);
}
else {
chunks.add(split);
DataBuffer joined = buffer.factory().join(chunks);
if (this.stripDelimiter) {
joined.writePosition(joined.writePosition() - delimiterLength);
}
result.add(joined);
chunks.clear();
}
}
while (buffer.readableByteCount() > 0);
return (result != null ? result : Collections.emptyList());
}
finally {
if (release) {
DataBufferUtils.release(buffer);
}
}
}
@Override
public final T decode(DataBuffer dataBuffer, ResolvableType elementType,
@Nullable MimeType mimeType, @Nullable Map hints) {
Charset charset = getCharset(mimeType);
T value = decodeInternal(dataBuffer, charset);
DataBufferUtils.release(dataBuffer);
LogFormatUtils.traceDebug(logger, traceOn -> {
String formatted = LogFormatUtils.formatValue(value, !traceOn);
return Hints.getLogPrefix(hints) + "Decoded " + formatted;
});
return value;
}
private Charset getCharset(@Nullable MimeType mimeType) {
if (mimeType != null) {
Charset charset = mimeType.getCharset();
if (charset != null) {
return charset;
}
}
return getDefaultCharset();
}
/**
* Template method that decodes the given data buffer into {@code T}, given
* the charset.
*/
protected abstract T decodeInternal(DataBuffer dataBuffer, Charset charset);
}