背压和操作符
转换并控制响应式流
背压和操作符 是 CoddyKit 上的免费 Spring Boot 4 Microservices & REST APIs 课时。 这是第 4 节课，共 4 节。 你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。 这是 Spring Boot 4 Microservices & REST APIs 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Spring Boot 4 Microservices & REST APIs 课程共包含 4 节课。
本课时的部分内容尚未翻译，以英文显示。
Operators Build Pipelines
Reactive operators chain together to form a processing pipeline. Each operator returns a new publisher describing the next step.
Common ones: map, flatMap, filter, take, buffer.
map vs flatMap
map transforms each item synchronously (1-to-1). flatMap transforms each item into another publisher and flattens the results — use it for async work.
Using map
map for pure, synchronous transformations.
Flux<Integer> lengths = Flux.just("a", "bb", "ccc")
.map(String::length);
lengths.subscribe(System.out::println); // 1, 2, 3Using flatMap
flatMap when each item triggers an async call returning a Mono or Flux.
Flux<User> users = Flux.just("1", "2", "3")
.flatMap(id -> userService.findById(id));
users.subscribe(System.out::println);flatMap Ordering
flatMap interleaves results as inner publishers complete, so order is not guaranteed. Use concatMap to preserve order.
Flux<User> ordered = Flux.just("1", "2", "3")
.concatMap(id -> userService.findById(id));What is Backpressure
Backpressure is the mechanism by which a slow consumer tells a fast producer to slow down.
Subscribers request a number of items; the producer only emits up to that demand. This prevents memory overflow.
Limiting with take
take requests only the first N items, then cancels the upstream.
Flux<Long> first3 = Flux.interval(Duration.ofMillis(100))
.take(3);
first3.subscribe(System.out::println); // 0, 1, 2Buffering Items
buffer groups items into lists, useful for batching.
Flux<List<Integer>> batches = Flux.range(1, 10)
.buffer(3);
batches.subscribe(System.out::println);
// [1,2,3], [4,5,6], [7,8,9], [10]onBackpressureBuffer
When a producer is faster than the consumer, strategies control overflow: buffer, drop, or latest.
Flux.interval(Duration.ofMillis(1))
.onBackpressureBuffer(100)
.subscribe(System.out::println);Throttling with limitRate
limitRate caps how many items are requested upstream at a time, applying controlled backpressure.
Flux.range(1, 1000)
.limitRate(10)
.subscribe(System.out::println);Combining Operators
Real pipelines chain several operators to filter, transform, and limit a stream.
Flux.range(1, 100)
.filter(n -> n % 2 == 0)
.map(n -> n * n)
.take(5)
.subscribe(System.out::println);Quick Check
Test your understanding of operators and backpressure.
Recap
You learned about operators and backpressure:
map= sync transform;flatMap= async, unordered;concatMap= async, ordered- Backpressure lets slow consumers control fast producers
take,buffer,limitRateshape the stream
常见问题解答
「背压和操作符」课时是免费的吗？
是的 — 「背压和操作符」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Spring Boot 4 Microservices & REST APIs 课程的其余内容，请升级到 CoddyKit PRO。 Spring Boot 4 Microservices & REST APIs 课程共包含 4 节课。
「背压和操作符」这节课中我会学到什么？
转换并控制响应式流 你通过在浏览器中直接运行的动手代码来练习 Spring Boot 4 Microservices & REST APIs，全天候 AI 导师会在你学习这节课的过程中回答你的问题。
学习 Spring Boot 4 Microservices & REST APIs 需要有经验吗？
无需任何先前经验。CoddyKit 上的 Spring Boot 4 Microservices & REST APIs 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。 这是第 4 节课，共 4 节。
「背压和操作符」课时需要多长时间？
大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。
我能在这节 Spring Boot 4 Microservices & REST APIs 课中编写并运行代码吗？
能。每节 Spring Boot 4 Microservices & REST APIs 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。