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 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.DataBufferUtils;
import org.springframework.core.io.buffer.DefaultDataBufferFactory;
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 {
private static final DataBuffer END_FRAME = new DefaultDataBufferFactory().wrap(new byte[0]);
/** 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) {
List delimiterBytes = getDelimiterBytes(mimeType);
Flux inputFlux = Flux.from(input)
.flatMapIterable(buffer -> splitOnDelimiter(buffer, delimiterBytes))
.bufferUntil(buffer -> buffer == END_FRAME)
.map(StringDecoder::joinUntilEndFrame)
.doOnDiscard(PooledDataBuffer.class, DataBufferUtils::release);
return super.decode(inputFlux, elementType, mimeType, hints);
}
private List getDelimiterBytes(@Nullable MimeType mimeType) {
return this.delimitersCache.computeIfAbsent(getCharset(mimeType), charset -> {
List list = new ArrayList<>();
for (String delimiter : this.delimiters) {
byte[] bytes = delimiter.getBytes(charset);
list.add(bytes);
}
return list;
});
}
/**
* Split the given data buffer on delimiter boundaries.
* The returned Flux contains an {@link #END_FRAME} buffer after each delimiter.
*/
private List splitOnDelimiter(DataBuffer buffer, List delimiterBytes) {
List frames = new ArrayList<>();
try {
do {
int length = Integer.MAX_VALUE;
byte[] matchingDelimiter = null;
for (byte[] delimiter : delimiterBytes) {
int index = indexOf(buffer, delimiter);
if (index >= 0 && index < length) {
length = index;
matchingDelimiter = delimiter;
}
}
DataBuffer frame;
int readPosition = buffer.readPosition();
if (matchingDelimiter != null) {
frame = this.stripDelimiter ?
buffer.slice(readPosition, length) :
buffer.slice(readPosition, length + matchingDelimiter.length);
buffer.readPosition(readPosition + length + matchingDelimiter.length);
frames.add(DataBufferUtils.retain(frame));
frames.add(END_FRAME);
}
else {
frame = buffer.slice(readPosition, buffer.readableByteCount());
buffer.readPosition(readPosition + buffer.readableByteCount());
frames.add(DataBufferUtils.retain(frame));
}
}
while (buffer.readableByteCount() > 0);
}
catch (Throwable ex) {
for (DataBuffer frame : frames) {
DataBufferUtils.release(frame);
}
throw ex;
}
finally {
DataBufferUtils.release(buffer);
}
return frames;
}
/**
* Find the given delimiter in the given data buffer.
* @return the index of the delimiter, or -1 if not found.
*/
private static int indexOf(DataBuffer buffer, byte[] delimiter) {
for (int i = buffer.readPosition(); i < buffer.writePosition(); i++) {
int bufferPos = i;
int delimiterPos = 0;
while (delimiterPos < delimiter.length) {
if (buffer.getByte(bufferPos) != delimiter[delimiterPos]) {
break;
}
else {
bufferPos++;
boolean endOfBuffer = bufferPos == buffer.writePosition();
boolean endOfDelimiter = delimiterPos == delimiter.length - 1;
if (endOfBuffer && !endOfDelimiter) {
return -1;
}
}
delimiterPos++;
}
if (delimiterPos == delimiter.length) {
return i - buffer.readPosition();
}
}
return -1;
}
/**
* Join the given list of buffers into a single buffer.
*/
private static DataBuffer joinUntilEndFrame(List dataBuffers) {
if (!dataBuffers.isEmpty()) {
int lastIdx = dataBuffers.size() - 1;
if (dataBuffers.get(lastIdx) == END_FRAME) {
dataBuffers.remove(lastIdx);
}
}
return dataBuffers.get(0).factory().join(dataBuffers);
}
@Override
protected String decodeDataBuffer(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;
}
}
/**
* 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);
}
}