如何在每次更改变量时生成事件流？

Question

我想每次改变整数变量时发送更新

@PutMapping
public void update() {
    integer = random.nextInt();
}

@GetMapping(produces = MediaType.TEXT_EVENT_STREAM_VALUE)
public Flux<Integer> eventFlux() {
    Flux<Integer> eventFlux = Flux.fromStream(
            Stream.generate(() -> integer)
    );
    return Flux.zip(eventFlux, onUpdate()).map(Tuple2::getT1);
}

private Flux<Long> onUpdate() {
    return Flux.interval(Duration.ofSeconds(1));
}

Answer 1

您可以使用一个FLUXPORTER作为：

• 上游用户；您可以使用它向其中添加数字：

    @PutMapping("/{number}")
    public void update(@PathVariable Integer number) {
        processor.onNext(number);
    }

• 下游Publisher（Flux）；哪些客户端可以订阅接收添加的号码：

    @GetMapping(produces = MediaType.TEXT_EVENT_STREAM_VALUE)
    public Flux<Integer> eventFlux() {
        return processor;
    }

以下是一个完整的工作示例：

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.reactive.config.EnableWebFlux;
import org.springframework.web.reactive.config.WebFluxConfigurer;

import reactor.core.publisher.DirectProcessor;
import reactor.core.publisher.Flux;
import reactor.core.publisher.FluxProcessor;

@SpringBootApplication
@EnableWebFlux
@RestController
public class EventStreamApp implements WebFluxConfigurer {

    public static void main(String[] args) {
        SpringApplication.run(EventStreamApp.class);
    }

    private FluxProcessor<Integer, Integer> processor = DirectProcessor.create();

    @PutMapping("/{number}")
    public void update(@PathVariable Integer number) {
        processor.onNext(number);
    }

    @GetMapping(produces = MediaType.TEXT_EVENT_STREAM_VALUE)
    public Flux<Integer> eventFlux() {
        return processor;
    }
}

GitHub上的完整代码

希望这能有所帮助。