<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

<!-- 若使用WebFlux方式 -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-webflux</artifactId>
</dependency>

@RestController
public class SseController {

    @GetMapping("/sse")
    public SseEmitter handleSse() {
        SseEmitter emitter = new SseEmitter();
        ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor();

        Runnable task = () -> {
            try {
                String data = "Time: " + LocalDateTime.now();
                emitter.send(
                    SseEmitter.event()
                        .data(data)
                        .id(String.valueOf(System.currentTimeMillis()))
                );
            } catch (IOException e) {
                emitter.completeWithError(e);
                executor.shutdown();
            }
        };

        // 定時(shí)發(fā)送（立即執(zhí)行，每秒一次）
        executor.scheduleAtFixedRate(task, 0, 1, TimeUnit.SECONDS);

        // 客戶(hù)端斷開(kāi)處理
        emitter.onCompletion(executor::shutdown);
        emitter.onTimeout(executor::shutdown);

        return emitter;
    }
}

@RestController
public class SseWebFluxController {

    @GetMapping(value = "/sse-stream", 
               produces = MediaType.TEXT_EVENT_STREAM_VALUE)
    public Flux<ServerSentEvent<String>> streamEvents() {
        return Flux.interval(Duration.ofSeconds(1))
            .map(sequence -> ServerSentEvent.<String>builder()
                .id(String.valueOf(sequence))
                .event("time-update")
                .data("SSE from WebFlux - " + LocalDateTime.now())
                .build());
    }
}

const eventSource = new EventSource('/sse');

eventSource.onmessage = (e) => {
    console.log('Received:', e.data);
};

eventSource.addEventListener('time-update', (e) => {
    console.log('Custom event:', e.data);
});

@Configuration
public class WebConfig implements WebMvcConfigurer {
    @Override
    public void addCorsMappings(CorsRegistry registry) {
        registry.addMapping("/sse*")
                .allowedOrigins("*");
    }
}