org.springframework.core.codec.StringDecoder Maven / Gradle / Ivy
/*
* Copyright 2002-2019 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.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.function.Consumer;
import org.reactivestreams.Publisher;
import reactor.core.publisher.Flux;
import org.springframework.core.ResolvableType;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.core.io.buffer.DataBufferLimitException;
import org.springframework.core.io.buffer.DataBufferUtils;
import org.springframework.core.io.buffer.DataBufferWrapper;
import org.springframework.core.io.buffer.DefaultDataBufferFactory;
import org.springframework.core.io.buffer.LimitedDataBufferList;
import org.springframework.core.io.buffer.PooledDataBuffer;
import org.springframework.core.log.LogFormatUtils;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.MimeType;
import org.springframework.util.MimeTypeUtils;
/**
* Decode from a data buffer stream to a {@code String} stream. Before decoding, this decoder
* realigns the incoming data buffers so that each buffer ends with a newline.
* This is to make sure that multibyte characters are decoded properly, and do not cross buffer
* boundaries. The default delimiters ({@code \n}, {@code \r\n})can be customized.
*
* Partially inspired by Netty's {@code DelimiterBasedFrameDecoder}.
*
* @author Sebastien Deleuze
* @author Brian Clozel
* @author Arjen Poutsma
* @author Mark Paluch
* @since 5.0
* @see CharSequenceEncoder
*/
public final class StringDecoder 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 = Arrays.asList("\r\n", "\n");
private final List delimiters;
private final boolean stripDelimiter;
private final ConcurrentMap delimitersCache = new ConcurrentHashMap<>();
private StringDecoder(List delimiters, boolean stripDelimiter, MimeType... mimeTypes) {
super(mimeTypes);
Assert.notEmpty(delimiters, "'delimiters' must not be empty");
this.delimiters = new ArrayList<>(delimiters);
this.stripDelimiter = stripDelimiter;
}
@Override
public boolean canDecode(ResolvableType elementType, @Nullable MimeType mimeType) {
return (elementType.resolve() == String.class && super.canDecode(elementType, mimeType));
}
@Override
public Flux decode(Publisher input, ResolvableType elementType,
@Nullable MimeType mimeType, @Nullable Map hints) {
byte[][] delimiterBytes = getDelimiterBytes(mimeType);
// TODO: Drop Consumer and use bufferUntil with Supplier (reactor-core#1925)
// TODO: Drop doOnDiscard(LimitedDataBufferList.class, ...) (reactor-core#1924)
LimitedDataBufferConsumer limiter = new LimitedDataBufferConsumer(getMaxInMemorySize());
Flux inputFlux = Flux.defer(() -> {
DataBufferUtils.Matcher matcher = DataBufferUtils.matcher(delimiterBytes);
return Flux.from(input)
.concatMapIterable(buffer -> endFrameAfterDelimiter(buffer, matcher))
.doOnNext(limiter)
.bufferUntil(buffer -> buffer instanceof EndFrameBuffer)
.map(buffers -> joinAndStrip(buffers, this.stripDelimiter))
.doOnDiscard(LimitedDataBufferList.class, LimitedDataBufferList::releaseAndClear)
.doOnDiscard(PooledDataBuffer.class, DataBufferUtils::release);
});
return super.decode(inputFlux, 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;
});
}
@Override
public String decode(DataBuffer dataBuffer, ResolvableType elementType,
@Nullable MimeType mimeType, @Nullable Map hints) {
Charset charset = getCharset(mimeType);
CharBuffer charBuffer = charset.decode(dataBuffer.asByteBuffer());
DataBufferUtils.release(dataBuffer);
String value = charBuffer.toString();
LogFormatUtils.traceDebug(logger, traceOn -> {
String formatted = LogFormatUtils.formatValue(value, !traceOn);
return Hints.getLogPrefix(hints) + "Decoded " + formatted;
});
return value;
}
private static Charset getCharset(@Nullable MimeType mimeType) {
if (mimeType != null && mimeType.getCharset() != null) {
return mimeType.getCharset();
}
else {
return DEFAULT_CHARSET;
}
}
/**
* Finds the first match and longest delimiter, {@link EndFrameBuffer} just after it.
*
* @param dataBuffer the buffer to find delimiters in
* @param matcher used to find the first delimiters
* @return a flux of buffers, containing {@link EndFrameBuffer} after each delimiter that was
* found in {@code dataBuffer}. Returns Flux, because returning List (w/ flatMapIterable)
* results in memory leaks due to pre-fetching.
*/
private static List endFrameAfterDelimiter(DataBuffer dataBuffer, DataBufferUtils.Matcher matcher) {
List result = new ArrayList<>();
do {
int endIdx = matcher.match(dataBuffer);
if (endIdx != -1) {
int readPosition = dataBuffer.readPosition();
int length = endIdx - readPosition + 1;
result.add(dataBuffer.retainedSlice(readPosition, length));
result.add(new EndFrameBuffer(matcher.delimiter()));
dataBuffer.readPosition(endIdx + 1);
}
else {
result.add(DataBufferUtils.retain(dataBuffer));
break;
}
}
while (dataBuffer.readableByteCount() > 0);
DataBufferUtils.release(dataBuffer);
return result;
}
/**
* Joins the given list of buffers. If the list ends with a {@link EndFrameBuffer}, it is
* removed. If {@code stripDelimiter} is {@code true} and the resulting buffer ends with
* a delimiter, it is removed.
* @param dataBuffers the data buffers to join
* @param stripDelimiter whether to strip the delimiter
* @return the joined buffer
*/
private static DataBuffer joinAndStrip(List dataBuffers,
boolean stripDelimiter) {
Assert.state(!dataBuffers.isEmpty(), "DataBuffers should not be empty");
byte[] matchingDelimiter = null;
int lastIdx = dataBuffers.size() - 1;
DataBuffer lastBuffer = dataBuffers.get(lastIdx);
if (lastBuffer instanceof EndFrameBuffer) {
matchingDelimiter = ((EndFrameBuffer) lastBuffer).delimiter();
dataBuffers.remove(lastIdx);
}
DataBuffer result = dataBuffers.get(0).factory().join(dataBuffers);
if (stripDelimiter && matchingDelimiter != null) {
result.writePosition(result.writePosition() - matchingDelimiter.length);
}
return result;
}
/**
* Create a {@code StringDecoder} for {@code "text/plain"}.
* @param ignored ignored
* @deprecated as of Spring 5.0.4, in favor of {@link #textPlainOnly()} or
* {@link #textPlainOnly(List, boolean)}
*/
@Deprecated
public static StringDecoder textPlainOnly(boolean ignored) {
return textPlainOnly();
}
/**
* Create a {@code StringDecoder} for {@code "text/plain"}.
*/
public static StringDecoder textPlainOnly() {
return textPlainOnly(DEFAULT_DELIMITERS, true);
}
/**
* Create a {@code StringDecoder} for {@code "text/plain"}.
* @param delimiters delimiter strings to use to split the input stream
* @param stripDelimiter whether to remove delimiters from the resulting
* input strings
*/
public static StringDecoder textPlainOnly(List delimiters, boolean stripDelimiter) {
return new StringDecoder(delimiters, stripDelimiter, new MimeType("text", "plain", DEFAULT_CHARSET));
}
/**
* Create a {@code StringDecoder} that supports all MIME types.
* @param ignored ignored
* @deprecated as of Spring 5.0.4, in favor of {@link #allMimeTypes()} or
* {@link #allMimeTypes(List, boolean)}
*/
@Deprecated
public static StringDecoder allMimeTypes(boolean ignored) {
return allMimeTypes();
}
/**
* Create a {@code StringDecoder} that supports all MIME types.
*/
public static StringDecoder allMimeTypes() {
return allMimeTypes(DEFAULT_DELIMITERS, true);
}
/**
* Create a {@code StringDecoder} that supports all MIME types.
* @param delimiters delimiter strings to use to split the input stream
* @param stripDelimiter whether to remove delimiters from the resulting
* input strings
*/
public static StringDecoder allMimeTypes(List delimiters, boolean stripDelimiter) {
return new StringDecoder(delimiters, stripDelimiter,
new MimeType("text", "plain", DEFAULT_CHARSET), MimeTypeUtils.ALL);
}
private static class EndFrameBuffer extends DataBufferWrapper {
private static final DataBuffer BUFFER = new DefaultDataBufferFactory().wrap(new byte[0]);
private byte[] delimiter;
public EndFrameBuffer(byte[] delimiter) {
super(BUFFER);
this.delimiter = delimiter;
}
public byte[] delimiter() {
return this.delimiter;
}
}
/**
* Temporary measure for reactor-core#1925.
* Consumer that adds to a {@link LimitedDataBufferList} to enforce limits.
*/
private static class LimitedDataBufferConsumer implements Consumer {
private final LimitedDataBufferList bufferList;
public LimitedDataBufferConsumer(int maxInMemorySize) {
this.bufferList = new LimitedDataBufferList(maxInMemorySize);
}
@Override
public void accept(DataBuffer buffer) {
if (buffer instanceof EndFrameBuffer) {
this.bufferList.clear();
}
else {
try {
this.bufferList.add(buffer);
}
catch (DataBufferLimitException ex) {
DataBufferUtils.release(buffer);
throw ex;
}
}
}
}
}