Spring Boot 4 Microservices & REST APIs · 课时

使用 Micrometer 自定义指标

记录应用专属的指标

第 3 / 4 课13 个步骤

使用 Micrometer 自定义指标 是 CoddyKit 上的免费 Spring Boot 4 Microservices & REST APIs 课时。这是第 3 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。

Micrometer: The Metrics Facade

Spring Boot uses Micrometer as a vendor-neutral metrics facade — the SLF4J of metrics. You instrument code against one API, then export to Prometheus, Datadog, CloudWatch, and others by adding a registry.

The MeterRegistry

The central component is the MeterRegistry. Boot auto-configures one and registers it as a bean, so you simply inject it wherever you need to record measurements.

@Service
public class OrderService {
    private final MeterRegistry registry;
    public OrderService(MeterRegistry registry) {
        this.registry = registry;
    }
}

Counters

A Counter records a value that only increases — perfect for counting events like orders placed or errors encountered. Create it once and increment it as events occur.

@Service
public class OrderService {
    private final Counter ordersPlaced;
    public OrderService(MeterRegistry registry) {
        this.ordersPlaced = registry.counter("orders.placed");
    }
    public void place(Order o) {
        // ... business logic
        ordersPlaced.increment();
    }
}

Tags (Dimensions)

Add tags to slice a metric by dimension — channel, region, status. Each unique tag combination is a separate time series, so keep tag cardinality bounded.

registry.counter("orders.placed",
        "channel", "web",
        "region", "eu")
    .increment();

Timers

A Timer measures both how often something happens and how long it takes, yielding count, total time, and max. Use it to track operation latency.

Timer timer = registry.timer("orders.process.time");
timer.record(() -> processOrder(order));

Recording Time Manually

When you cannot wrap the work in a lambda, capture a Timer.Sample at the start and stop it against a timer at the end.

Timer.Sample sample = Timer.start(registry);
try {
    processOrder(order);
} finally {
    sample.stop(registry.timer("orders.process.time"));
}

Gauges

A Gauge reports a value that can go up or down — a queue depth, active sessions, cache size. You register a function that Micrometer samples on demand.

registry.gauge("orders.queue.size",
    orderQueue, q -> q.size());

Distribution Summaries

A DistributionSummary tracks the distribution of arbitrary values, such as request payload sizes, providing count, total, and percentiles.

DistributionSummary summary = registry.summary("orders.amount");
summary.record(order.getTotal().doubleValue());

Declarative Timing with @Timed

The @Timed annotation times a method without manual instrumentation. It requires a TimedAspect bean to be registered.

@Bean
TimedAspect timedAspect(MeterRegistry registry) {
    return new TimedAspect(registry);
}

@Timed(value = "orders.process.time")
public void process(Order o) { /* ... */ }

Exporting to Prometheus

Add the Prometheus registry dependency and expose the prometheus endpoint. Micrometer then publishes a scrape endpoint with all your meters.

# dependency: micrometer-registry-prometheus
management:
  endpoints:
    web:
      exposure:
        include: prometheus,metrics,health
# scrape: /actuator/prometheus

Cardinality Discipline

The biggest metrics pitfall is high-cardinality tags. Never tag with user ids, request ids, or raw URLs — each unique value multiplies time series and can overwhelm your backend.

Quick Check

Test your understanding of meter types.

在交互式课程中回答

Recap

Micrometer instruments your app.

Inject the auto-configured MeterRegistry
Counter for monotonic counts, Timer for latency
Gauge for fluctuating values, DistributionSummary for distributions
Use bounded tags; avoid high cardinality
Export to Prometheus and friends via a registry dependency

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常见问题解答

「使用 Micrometer 自定义指标」课时是免费的吗？

是的 — 「使用 Micrometer 自定义指标」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。

「使用 Micrometer 自定义指标」这节课中我会学到什么？

记录应用专属的指标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 3 节课，共 4 节。

「使用 Micrometer 自定义指标」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。

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