springboot -sse -flux 服务器推送消息

先说BUG处理，遇到提示异步问题 Async support must be enabled on a servlet and for all filters involved in async request processing. This is done in Java code using the Servlet API or by adding "true" to servlet and filter declarations in web.xml.

springboot在@WebFilter注解处，加入urlPatterns = { "/*" },asyncSupported = true

springmvc在web.xml处理

  shiroFilter
  /*
  REQUEST
  ASYNC

• demo1，服务器间隔一定时间推送内容

1.     接口方法

@GetMapping(path = "/sse/{userId}",produces = MediaType.TEXT_EVENT_STREAM_VALUE )
	public Flux> sse(@PathVariable String userId) {
        // 每两秒推送一次
        return Flux.interval(Duration.ofSeconds(2)).map(seq->
            Tuples.of(seq, LocalDateTime.now())).log()//序号和时间
                .map(data-> ServerSentEvent.builder().id(userId).data(data.getT1().toString()).build());//推送内容
        
    }

2.前端代码

• demo2 订阅服务器消息，服务器send推送消息完成后，关闭sse.close

1.接口方法以及工具类

@GetMapping(path = "/sse/sub",produces = MediaType.TEXT_EVENT_STREAM_VALUE )
public SseEmitter subscribe(@RequestParam String questionId,HttpServletResponse response) {
		// 简单异步发消息 ====
        //questionId 订阅id，id对应了sse对象
        new Thread(() -> {
            try {
                Thread.sleep(1000);
                for (int i = 0; i < 10; i++) {
                    Thread.sleep(500);
                    SSEUtils.pubMsg(questionId, questionId + " - kingtao come " + i);
                }
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                // 消息发送完关闭订阅
                SSEUtils.closeSub(questionId);
            }
        }).start();
        // =================

        return SSEUtils.addSub(questionId);
    }

工具类

import org.springframework.web.servlet.mvc.method.annotation.SseEmitter;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

public class SSEUtils {
    // timeout
    private static Long DEFAULT_TIME_OUT = 2*60*1000L;
    // 订阅表
    private static Map subscribeMap = new ConcurrentHashMap<>();

    /** 添加订阅 */
    public static SseEmitter addSub(String questionId) {
        if (null == questionId || "".equals(questionId)) {
            return null;
        }

        SseEmitter emitter = subscribeMap.get(questionId);
        if (null == emitter) {
            emitter = new SseEmitter(DEFAULT_TIME_OUT);
            subscribeMap.put(questionId, emitter);
        }

        return emitter;
    }

    /** 发消息 */
    public static void pubMsg(String questionId, String msg) {
        SseEmitter emitter = subscribeMap.get(questionId);
        if (null != emitter) {
            try {
                // 更规范的消息结构看源码
                emitter.send(SseEmitter.event().data(msg));
            } catch (Exception e) {
                // e.printStackTrace();
            }
        }
    }

    /**
     * 关闭订阅 
     * @param questionId
     */
    public static void closeSub(String questionId) {
        SseEmitter emitter = subscribeMap.get(questionId);
        if (null != emitter) {
            try {
                emitter.complete();
                subscribeMap.remove(questionId);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}

2.前端代码

    
    



    问题id
    
    订阅
    

    F12-console控制台查看消息