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.stream.Collectors;
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;
public final class StringDecoder extends AbstractDataBufferDecoder<String> {
private static final DataBuffer END_FRAME = new DefaultDataBufferFactory().wrap(new byte[0]);
public static final Charset DEFAULT_CHARSET = StandardCharsets.UTF_8;
public static final List<String> DEFAULT_DELIMITERS = Arrays.asList("\r\n", "\n");
private final List<String> delimiters;
private final boolean stripDelimiter;
private final ConcurrentMap<Charset, List<byte[]>> delimitersCache = new ConcurrentHashMap<>();
private StringDecoder(List<String> 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<String> decode(Publisher<DataBuffer> inputStream, ResolvableType elementType,
@Nullable MimeType mimeType, @Nullable Map<String, Object> hints) {
List<byte[]> delimiterBytes = getDelimiterBytes(mimeType);
Flux<DataBuffer> inputFlux = Flux.from(inputStream)
.flatMapIterable(dataBuffer -> splitOnDelimiter(dataBuffer, delimiterBytes))
.bufferUntil(StringDecoder::isEndFrame)
.map(StringDecoder::joinUntilEndFrame)
.doOnDiscard(PooledDataBuffer.class, DataBufferUtils::release);
return super.decode(inputFlux, elementType, mimeType, hints);
}
private List<byte[]> getDelimiterBytes(@Nullable MimeType mimeType) {
return this.delimitersCache.computeIfAbsent(getCharset(mimeType),
charset -> this.delimiters.stream()
.map(s -> s.getBytes(charset))
.collect(Collectors.toList()));
}
private List<DataBuffer> splitOnDelimiter(DataBuffer dataBuffer, List<byte[]> delimiterBytes) {
List<DataBuffer> frames = new ArrayList<>();
do {
int length = Integer.MAX_VALUE;
byte[] matchingDelimiter = null;
for (byte[] delimiter : delimiterBytes) {
int index = indexOf(dataBuffer, delimiter);
if (index >= 0 && index < length) {
length = index;
matchingDelimiter = delimiter;
}
}
DataBuffer frame;
int readPosition = dataBuffer.readPosition();
if (matchingDelimiter != null) {
if (this.stripDelimiter) {
frame = dataBuffer.slice(readPosition, length);
}
else {
frame = dataBuffer.slice(readPosition, length + matchingDelimiter.length);
}
dataBuffer.readPosition(readPosition + length + matchingDelimiter.length);
frames.add(DataBufferUtils.retain(frame));
frames.add(END_FRAME);
}
else {
frame = dataBuffer.slice(readPosition, dataBuffer.readableByteCount());
dataBuffer.readPosition(readPosition + dataBuffer.readableByteCount());
frames.add(DataBufferUtils.retain(frame));
}
}
while (dataBuffer.readableByteCount() > 0);
DataBufferUtils.release(dataBuffer);
return frames;
}
private static int indexOf(DataBuffer dataBuffer, byte[] delimiter) {
for (int i = dataBuffer.readPosition(); i < dataBuffer.writePosition(); i++) {
int dataBufferPos = i;
int delimiterPos = 0;
while (delimiterPos < delimiter.length) {
if (dataBuffer.getByte(dataBufferPos) != delimiter[delimiterPos]) {
break;
}
else {
dataBufferPos++;
if (dataBufferPos == dataBuffer.writePosition() &&
delimiterPos != delimiter.length - 1) {
return -1;
}
}
delimiterPos++;
}
if (delimiterPos == delimiter.length) {
return i - dataBuffer.readPosition();
}
}
return -1;
}
private static boolean isEndFrame(DataBuffer dataBuffer) {
return dataBuffer == END_FRAME;
}
private static DataBuffer joinUntilEndFrame(List<DataBuffer> dataBuffers) {
if (!dataBuffers.isEmpty()) {
int lastIdx = dataBuffers.size() - 1;
if (isEndFrame(dataBuffers.get(lastIdx))) {
dataBuffers.remove(lastIdx);
}
}
return dataBuffers.get(0).factory().join(dataBuffers);
}
@Override
protected String decodeDataBuffer(DataBuffer dataBuffer, ResolvableType elementType,
@Nullable MimeType mimeType, @Nullable Map<String, Object> 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;
}
}
@Deprecated
public static StringDecoder textPlainOnly(boolean ignored) {
return textPlainOnly();
}
public static StringDecoder textPlainOnly() {
return textPlainOnly(DEFAULT_DELIMITERS, true);
}
public static StringDecoder textPlainOnly(List<String> delimiters, boolean stripDelimiter) {
return new StringDecoder(delimiters, stripDelimiter, new MimeType("text", "plain", DEFAULT_CHARSET));
}
@Deprecated
public static StringDecoder allMimeTypes(boolean ignored) {
return allMimeTypes();
}
public static StringDecoder allMimeTypes() {
return allMimeTypes(DEFAULT_DELIMITERS, true);
}
public static StringDecoder allMimeTypes(List<String> delimiters, boolean stripDelimiter) {
return new StringDecoder(delimiters, stripDelimiter,
new MimeType("text", "plain", DEFAULT_CHARSET), MimeTypeUtils.ALL);
}
}