/*
* Copyright 2002-2017 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
*
* http://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.http.codec;
import java.nio.CharBuffer;
import java.nio.charset.StandardCharsets;
import java.time.Duration;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.function.IntPredicate;
import reactor.core.publisher.Flux;
import reactor.core.publisher.Mono;
import org.springframework.core.ResolvableType;
import org.springframework.core.codec.Decoder;
import org.springframework.core.codec.StringDecoder;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.core.io.buffer.DataBufferFactory;
import org.springframework.core.io.buffer.DataBufferUtils;
import org.springframework.core.io.buffer.DefaultDataBufferFactory;
import org.springframework.http.MediaType;
import org.springframework.http.ReactiveHttpInputMessage;
import static java.util.stream.Collectors.joining;
/**
* Reader that supports a stream of {@link ServerSentEvent}s and also plain
* {@link Object}s which is the same as an {@link ServerSentEvent} with data
* only.
*
* @author Sebastien Deleuze
* @author Rossen Stoyanchev
* @since 5.0
*/
public class ServerSentEventHttpMessageReader implements HttpMessageReader<Object> {
private static final IntPredicate NEWLINE_DELIMITER = b -> b == '\n' || b == '\r';
private static final DataBufferFactory bufferFactory = new DefaultDataBufferFactory();
private static final StringDecoder stringDecoder = StringDecoder.textPlainOnly(false);
private final Decoder<?> decoder;
/**
* Constructor without a {@code Decoder}. In this mode only {@code String}
* is supported as the data of an event.
*/
public ServerSentEventHttpMessageReader() {
this(null);
}
/**
* Constructor with JSON {@code Decoder} for decoding to Objects. Support
* for decoding to {@code String} event data is built-in.
*/
public ServerSentEventHttpMessageReader(Decoder<?> decoder) {
this.decoder = decoder;
}
/**
* Return the configured {@code Decoder}.
*/
public Decoder<?> getDecoder() {
return this.decoder;
}
@Override
public List<MediaType> getReadableMediaTypes() {
return Collections.singletonList(MediaType.TEXT_EVENT_STREAM);
}
@Override
public boolean canRead(ResolvableType elementType, MediaType mediaType) {
return MediaType.TEXT_EVENT_STREAM.includes(mediaType) ||
ServerSentEvent.class.isAssignableFrom(elementType.getRawClass());
}
@Override
public Flux<Object> read(ResolvableType elementType, ReactiveHttpInputMessage message,
Map<String, Object> hints) {
boolean shouldWrap = ServerSentEvent.class.isAssignableFrom(elementType.getRawClass());
ResolvableType valueType = shouldWrap ? elementType.getGeneric(0) : elementType;
return Flux.from(message.getBody())
.concatMap(ServerSentEventHttpMessageReader::splitOnNewline)
.map(buffer -> {
CharBuffer charBuffer = StandardCharsets.UTF_8.decode(buffer.asByteBuffer());
DataBufferUtils.release(buffer);
return charBuffer.toString();
})
.bufferUntil(line -> line.equals("\n"))
.concatMap(rawLines -> {
String[] lines = rawLines.stream().collect(joining()).split("\\r?\\n");
ServerSentEvent<Object> event = buildEvent(lines, valueType, hints);
return (shouldWrap ? Mono.just(event) : Mono.justOrEmpty(event.data()));
})
.cast(Object.class);
}
private static Flux<DataBuffer> splitOnNewline(DataBuffer dataBuffer) {
List<DataBuffer> results = new ArrayList<>();
int startIdx = 0;
int endIdx;
final int limit = dataBuffer.readableByteCount();
do {
endIdx = dataBuffer.indexOf(NEWLINE_DELIMITER, startIdx);
int length = endIdx != -1 ? endIdx - startIdx + 1 : limit - startIdx;
DataBuffer token = dataBuffer.slice(startIdx, length);
results.add(DataBufferUtils.retain(token));
startIdx = endIdx + 1;
}
while (startIdx < limit && endIdx != -1);
DataBufferUtils.release(dataBuffer);
return Flux.fromIterable(results);
}
private ServerSentEvent<Object> buildEvent(String[] lines, ResolvableType valueType,
Map<String, Object> hints) {
ServerSentEvent.Builder<Object> sseBuilder = ServerSentEvent.builder();
StringBuilder mutableData = new StringBuilder();
StringBuilder mutableComment = new StringBuilder();
for (String line : lines) {
if (line.startsWith("id:")) {
sseBuilder.id(line.substring(3));
}
else if (line.startsWith("event:")) {
sseBuilder.event(line.substring(6));
}
else if (line.startsWith("data:")) {
mutableData.append(line.substring(5)).append("\n");
}
else if (line.startsWith("retry:")) {
sseBuilder.retry(Duration.ofMillis(Long.valueOf(line.substring(6))));
}
else if (line.startsWith(":")) {
mutableComment.append(line.substring(1)).append("\n");
}
}
if (mutableData.length() > 0) {
String data = mutableData.toString();
sseBuilder.data(decodeData(data, valueType, hints));
}
if (mutableComment.length() > 0) {
String comment = mutableComment.toString();
sseBuilder.comment(comment.substring(0, comment.length() - 1));
}
return sseBuilder.build();
}
private Object decodeData(String data, ResolvableType dataType, Map<String, Object> hints) {
if (String.class.isAssignableFrom(dataType.getRawClass())) {
return data.substring(0, data.length() - 1);
}
byte[] bytes = data.getBytes(StandardCharsets.UTF_8);
Mono<DataBuffer> input = Mono.just(bufferFactory.wrap(bytes));
return this.decoder
.decodeToMono(input, dataType, MediaType.TEXT_EVENT_STREAM, hints)
.block(Duration.ZERO);
}
@Override
public Mono<Object> readMono(ResolvableType elementType, ReactiveHttpInputMessage message,
Map<String, Object> hints) {
// We're ahead of String + "*/*"
// Let's see if we can aggregate the output (lest we time out)...
if (String.class.equals(elementType.getRawClass())) {
Flux<DataBuffer> body = message.getBody();
return stringDecoder.decodeToMono(body, elementType, null, null).cast(Object.class);
}
return Mono.error(new UnsupportedOperationException(
"ServerSentEventHttpMessageReader only supports reading stream of events as a Flux"));
}
}