SpringBoot实时推送的三个经典案例

@Controller
@RequestMapping(“/polling”)
public class PollingController {
// 存放监听某个Id的长轮询集合
public static Multimap<String, DeferredResult> watchRequests = Multimaps.synchronizedMultimap(HashMultimap.create());
@GetMapping(path = "watch/{id}")
@ResponseBody
public DeferredResult<String> watch(@PathVariable String id) {
    DeferredResult<String> deferredResult = new DeferredResult<>(TIME_OUT);
    deferredResult.onCompletion(() -> watchRequests.remove(id, deferredResult));
    watchRequests.put(id, deferredResult);
    return deferredResult;
}
@GetMapping(path = "publish/{id}")
@ResponseBody
public String publish(@PathVariable String id) {
    if (watchRequests.containsKey(id)) {
        Collection<DeferredResult<String>> deferredResults = watchRequests.get(id);
        for (DeferredResult<String> deferredResult : deferredResults) {
            deferredResult.setResult("我更新了" + new Date());
        }
    }
    return "Published";
}
}

@Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {
@Override
public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
registry.addHandler(new WebSocketHandler(), “/ws”).setAllowedOrigins(“*”);
}
}

public class WebSocketHandler extends TextWebSocketHandler {
@Override
protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
String payload = message.getPayload();
session.sendMessage(new TextMessage("Hello, " + payload + “!”));
}
}

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-graphql</artifactId>
    <version>2.7.9</version>
</dependency>

type Message {
id: ID!
content: String!
}

type Subscription {
newMessage: Message
}

@Component
public class GraphQLSubscriptionResolver {
private Publisher messagePublisher = Flux.create(emitter -> {
// 模拟消息发布
ScheduledExecutorService executor = Executors.newScheduledThreadPool(1);
executor.scheduleAtFixedRate(() -> {
Message message = new Message();
message.setId(UUID.randomUUID().toString());
message.setContent("New message at " + new Date());
emitter.next(message);
}, 0, 5, TimeUnit.SECONDS);
});
@SubscriptionMapping
public Publisher<Message> newMessage() {
    return messagePublisher;
}}