/*
* Copyright 2002-2016 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.time.Duration;
import java.util.Optional;
import org.springframework.http.codec.json.Jackson2JsonEncoder;
/**
* Representation for a Server-Sent Event for use with Spring's reactive Web
* support. {@code Flux<ServerSentEvent>} or {@code Observable<ServerSentEvent>} is the
* reactive equivalent to Spring MVC's {@code SseEmitter}.
*
* @param <T> the type of data that this event contains
* @author Sebastien Deleuze
* @author Arjen Poutsma
* @see ServerSentEventHttpMessageWriter
* @see <a href="https://www.w3.org/TR/eventsource/">Server-Sent Events W3C recommendation</a>
* @since 5.0
*/
public class ServerSentEvent<T> {
private final String id;
private final String event;
private final T data;
private final Duration retry;
private final String comment;
private ServerSentEvent(String id, String event, T data, Duration retry, String comment) {
this.id = id;
this.event = event;
this.data = data;
this.retry = retry;
this.comment = comment;
}
/**
* Return a builder for a {@code SseEvent}.
*
* @param <T> the type of data that this event contains
* @return the builder
*/
public static <T> Builder<T> builder() {
return new BuilderImpl<>();
}
/**
* Return a builder for a {@code SseEvent}, populated with the give {@linkplain #data() data}.
*
* @param <T> the type of data that this event contains
* @return the builder
*/
public static <T> Builder<T> builder(T data) {
return new BuilderImpl<>(data);
}
/**
* Return the {@code id} field of this event, if available.
*/
public Optional<String> id() {
return Optional.ofNullable(this.id);
}
/**
* Return the {@code event} field of this event, if available.
*/
public Optional<String> event() {
return Optional.ofNullable(this.event);
}
/**
* Return the {@code data} field of this event, if available.
*/
public Optional<T> data() {
return Optional.ofNullable(this.data);
}
/**
* Return the {@code retry} field of this event, if available.
*/
public Optional<Duration> retry() {
return Optional.ofNullable(this.retry);
}
/**
* Return the comment of this event, if available.
*/
public Optional<String> comment() {
return Optional.ofNullable(this.comment);
}
@Override
public String toString() {
return "ServerSentEvent [id = '" + id + '\'' + ", event='" + event + '\'' +
", data=" + data + ", retry=" + retry + ", comment='" + comment + '\'' +
']';
}
/**
* A mutable builder for a {@code SseEvent}.
*
* @param <T> the type of data that this event contains
*/
public interface Builder<T> {
/**
* Set the value of the {@code id} field.
*
* @param id the value of the id field
* @return {@code this} builder
*/
Builder<T> id(String id);
/**
* Set the value of the {@code event} field.
*
* @param event the value of the event field
* @return {@code this} builder
*/
Builder<T> event(String event);
/**
* Set the value of the {@code data} field. If the {@code data} argument is a multi-line {@code String}, it
* will be turned into multiple {@code data} field lines as defined in Server-Sent Events
* W3C recommendation. If {@code data} is not a String, it will be
* {@linkplain Jackson2JsonEncoder encoded} into JSON.
*
* @param data the value of the data field
* @return {@code this} builder
*/
Builder<T> data(T data);
/**
* Set the value of the {@code retry} field.
*
* @param retry the value of the retry field
* @return {@code this} builder
*/
Builder<T> retry(Duration retry);
/**
* Set SSE comment. If a multi-line comment is provided, it will be turned into multiple
* SSE comment lines as defined in Server-Sent Events W3C
* recommendation.
*
* @param comment the comment to set
* @return {@code this} builder
*/
Builder<T> comment(String comment);
/**
* Builds the event.
*
* @return the built event
*/
ServerSentEvent<T> build();
}
private static class BuilderImpl<T> implements Builder<T> {
private T data;
private String id;
private String event;
private Duration retry;
private String comment;
public BuilderImpl() {
}
public BuilderImpl(T data) {
this.data = data;
}
@Override
public Builder<T> id(String id) {
this.id = id;
return this;
}
@Override
public Builder<T> event(String event) {
this.event = event;
return this;
}
@Override
public Builder<T> data(T data) {
this.data = data;
return this;
}
@Override
public Builder<T> retry(Duration retry) {
this.retry = retry;
return this;
}
@Override
public Builder<T> comment(String comment) {
this.comment = comment;
return this;
}
@Override
public ServerSentEvent<T> build() {
return new ServerSentEvent<T>(this.id, this.event, this.data, this.retry, this.comment);
}
}
}