012、Project Reactor

最新推荐文章于 2025-05-28 21:57:15 发布

转载最新推荐文章于 2025-05-28 21:57:15 发布 · 1.1k 阅读

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原文链接：https://my.oschina.net/tita/blog/3062656

文章标签：

#java #数据库

本文详细介绍了ProjectReactor的原理及其在Spring框架中的应用，包括解决回调地狱问题、依赖引入、示例代码演示以及与Redis和MongoDB的集成。

一、什么是Project Reactor

官网 https://projectreactor.io/

由表及里学 ProjectReactor http://blog.yannxia.top/2018/06/26/java/spring/projectreactor/

即响应式编程。主要解决了回调地狱（callback hell）的问题。

二、如何使用

1. 引入依赖

		<dependency>
			<groupId>io.projectreactor</groupId>
			<artifactId>reactor-core</artifactId>
		</dependency>

2. 例子

	@Override
	public void run(ApplicationArguments args) throws Exception {

		Flux.range(1, 6)
		        .doOnRequest(n -> log.info("Request {} number", n)) // 注意顺序造成的区别
		        .publishOn(Schedulers.elastic())
				.doOnComplete(() -> log.info("Publisher COMPLETE 1"))
				.map(i -> {
					log.info("Publish   thread: {}, i: {}", Thread.currentThread(), i);
//					return i / (3 - i);
					return i;
				})
//				.onErrorReturn(-1)  // onErrorReturn 和  onErrorResume 顺序，在前优先
				.onErrorResume(e -> {
					log.error("ErrorResume: {}", e.toString());
					return Mono.just(-2);
				})
				.doOnComplete(() -> log.info("Publisher COMPLETE 2"))
				.subscribeOn(Schedulers.elastic())
				.subscribe(i -> log.info("Subscribe thread: {}, i: {}", Thread.currentThread(), i)
						,e -> log.error("error: {}", e.toString())
						,() -> log.info("Subscriber COMPLETE")
//						,s -> s.request(4)
						);
		
		Thread.sleep(2000);
	}

二、redis with reactive

1. 引入依赖

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-redis-reactive</artifactId>
		</dependency>

2. 例子

	private void reactiveRedis() throws InterruptedException {
		ReactiveHashOperations<String, String, String> opsForHash = redisTemplate.opsForHash();
		
		String KEY = "reactor-redis";
		
		CountDownLatch countDownLatch = new CountDownLatch(1);
		
		Flux.fromArray(new String[] {"123", "456"})
		    .publishOn(Schedulers.single())
		    .doOnComplete(() -> log.info("list ok"))
		    .flatMap(c -> {
                log.info("try to put {}: {}", c, c);
                return opsForHash.put(KEY, c, c);
            })
		    .doOnComplete(() -> log.info("set ok"))
		    .concatWith(redisTemplate.expire(KEY, Duration.ofMinutes(1)))
		    .doOnComplete(() -> log.info("expire ok"))
		    .onErrorResume(e -> {
                log.error("exception {}", e.getMessage());
                return Mono.just(false);
            })
		    .subscribe(b -> log.info("subscribe: {}", b)
		    		,
                    e -> log.error("Exception {}", e.getMessage())
                    ,
                    () -> countDownLatch.countDown()
                    );
		    ;
		    
		    countDownLatch.await();
	}

三、mongodb with reactive

1. 引入依赖

		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-data-mongodb-reactive</artifactId>
		</dependency>

2. 例子

	private void reactiveMongo() throws InterruptedException {
		CountDownLatch cdl = new CountDownLatch(2);
		
		List<Coffee> objectsToSave = Arrays.asList(new Coffee().setName("猫屎咖啡").setPrice(19).setCreateTime(new Date()).setUpdateTime(new Date()),
				new Coffee().setName("拿铁咖啡").setPrice(15).setCreateTime(new Date()).setUpdateTime(new Date()));
		
		mongoTemplate.insertAll(objectsToSave)
		    .publishOn(Schedulers.elastic())
		    .doOnNext(c -> log.info("Next: {}", c))
		    .doOnComplete(() -> {
		    	log.info("Runnable");
		    	mongoTemplate.updateMulti(Query.query(Criteria.where("price").gte(16)),
						        new Update().inc("price", -5)
								    .currentDate("updateTime"),
								Coffee.class)
				    .doFinally(s -> {
						cdl.countDown();
						log.info("Finnally 2, {}", s);
					})
					.subscribe(r -> log.info("Result is {}", r));
		    })
		    .doFinally(s -> {
				cdl.countDown();
				log.info("Finnally 1, {}", s);
			})
		    .count()
		    .subscribe(c -> log.info("Insert {} records", c));
		
		cdl.await();
	}

源码

转载于:https://my.oschina.net/tita/blog/3062656