io.helidon.webclient.sse.SseSourceHandlerProvider Maven / Gradle / Ivy
/*
* Copyright (c) 2023, 2024 Oracle and/or its affiliates.
*
* 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 io.helidon.webclient.sse;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UncheckedIOException;
import java.nio.charset.StandardCharsets;
import java.time.Duration;
import io.helidon.common.GenericType;
import io.helidon.common.media.type.MediaTypes;
import io.helidon.http.media.MediaContext;
import io.helidon.http.sse.SseEvent;
import io.helidon.webclient.api.HttpClientResponse;
import io.helidon.webclient.spi.Source;
import io.helidon.webclient.spi.SourceHandlerProvider;
/**
* A handler for SSE sources.
*/
public class SseSourceHandlerProvider implements SourceHandlerProvider {
private static final char BOM = 0xFEFF;
private static final String ID = "id:";
private static final String DATA = "data:";
private static final String RETRY = "retry:";
private static final String EVENT = "event:";
@Override
public boolean supports(GenericType> type, HttpClientResponse response) {
return SseSource.TYPE.equals(type) && response.headers().contentType()
.map(ct -> ct.mediaType().equals(MediaTypes.TEXT_EVENT_STREAM)).orElse(false);
}
@Override
public > void handle(X source, HttpClientResponse response, MediaContext mediaContext) {
InputStream is = response.inputStream();
try (BufferedReader reader = new BufferedReader(new InputStreamReader(is, StandardCharsets.UTF_8))) {
String line;
boolean emit = false;
boolean first = true;
StringBuilder data = new StringBuilder();
SseEvent.Builder sseBuilder = SseEvent.builder().mediaContext(mediaContext);
source.onOpen();
while ((line = reader.readLine()) != null) {
if (first && line.charAt(0) == BOM) { // optional BOM
line = line.substring(1);
}
first = false;
if (line.isBlank()) {
if (emit) {
sseBuilder.data(data.toString());
source.onEvent(sseBuilder.build());
data.setLength(0);
sseBuilder = SseEvent.builder().mediaContext(mediaContext);
emit = false;
}
continue;
}
emit = true;
if (line.startsWith(DATA)) {
data.append(skipPrefix(line));
} else if (line.startsWith(EVENT)) {
sseBuilder.name(skipPrefix(line));
} else if (line.startsWith(ID)) {
sseBuilder.id(skipPrefix(line));
} else if (line.startsWith(RETRY)) {
long delay = Long.parseLong(skipPrefix(line));
sseBuilder.reconnectDelay(Duration.ofMillis(delay));
} else if (line.startsWith(":")) {
sseBuilder.comment(line.length() > 1 ? line.substring(1) : "");
} else {
emit = false;
}
}
source.onClose();
} catch (IOException e) {
source.onError(e);
throw new UncheckedIOException(e);
} catch (NumberFormatException e) {
source.onError(e);
throw e;
}
}
private static String skipPrefix(String line) {
StringBuilder builder = new StringBuilder(line.length());
int state = 0;
for (int i = 0; i < line.length(); i++) {
switch (state) {
case 0:
if (line.charAt(i) == ':') {
state = 1; // found delimiter
}
break;
case 1:
char ch = line.charAt(i);
if (ch != ' ') {
builder.append(ch);
state = 2; // stop skipping spaces
}
break;
case 2:
builder.append(line.charAt(i));
break;
default:
throw new IllegalStateException("Illegal SSE parser state for text/event-stream");
}
}
return builder.toString();
}
}