micrometer和Spring Boot 2.x是无缝集成的。

但是在有的情况下，我们需要在很老的框架下，也使用它，比如Spring 3.X。我略作了调整，改成了JDK 1.8。

为了简单期间，我从mykong上找了3.X的脚手架工程，可以参考这里。

1 添加pom依赖

<!-- for micrometer -->
<dependency>
  <groupId>javax.servlet</groupId>
  <artifactId>javax.servlet-api</artifactId>
  <version>3.0.1</version>
</dependency>

<dependency>
  <groupId>io.micrometer</groupId>
  <artifactId>micrometer-registry-jmx</artifactId>
  <version>1.8.7</version>
</dependency>

注意这里用的是servlet3.0，如果是2.5的话，后面没法拿response.status。

2 添加拦截器

这里的关键是需要手工造一个Registry，我这里直接用的JmxMeterRegistry，Prometheus也一样的原理。

package com.mkyong.web.interceptor;

import io.micrometer.core.instrument.Clock;
import io.micrometer.core.instrument.Counter;
import io.micrometer.core.instrument.DistributionSummary;
import io.micrometer.core.instrument.MeterRegistry;
import io.micrometer.jmx.JmxConfig;
import io.micrometer.jmx.JmxMeterRegistry;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.Optional;

public class MeterInterceptor implements HandlerInterceptor {

    private MeterRegistry meterRegistry = new JmxMeterRegistry(new JmxConfig() {
        @Override
        public String get(String s) {
            return null;
        }
    }, Clock.SYSTEM);

    private ThreadLocal<Long> tlTimer = new ThreadLocal<Long>();

    private static Optional<String> getMethod(HttpServletRequest request, Object handler) {
        if (handler instanceof HandlerMethod) {
            return Optional.of(String.format("%s_%s_%s", ((HandlerMethod) handler).getBeanType().getSimpleName(),
                    ((HandlerMethod) handler).getMethod().getName(), request.getMethod()));
        } else {
            return Optional.empty();
        }
    }

    private void recordTimeDistribution(HttpServletRequest request, Object handler, long ms) {
        Optional<String> methodOp = getMethod(request, handler);
        if (methodOp.isPresent()) {
            DistributionSummary.builder("app_requests_time_ms")
                    .tag("method", methodOp.get())
                    .publishPercentiles(0.5, 0.95)
                    .publishPercentileHistogram()
                    .register(meterRegistry)
                    .record(ms);
        }
    }

    public Optional<Counter> getCounterOfTotalCounts(HttpServletRequest request, Object handler) {
        Optional<String> methodOp = getMethod(request, handler);
        if (methodOp.isPresent()) {
            return Optional.of(meterRegistry.counter("app_requests_total_counts", "method",
                    methodOp.get()));
        } else {
            return Optional.empty();
        }
    }

    public Optional<Counter> getCounterOfExceptionCounts(HttpServletRequest request, Object handler) {
        Optional<String> methodOp = getMethod(request, handler);
        if (methodOp.isPresent()) {
            return Optional.of(meterRegistry.counter("app_requests_exption_counts", "method",
                    methodOp.get()));
        } else {
            return Optional.empty();
        }
    }

    public Optional<Counter> getCounterOfRespCodeCounts(HttpServletRequest request, HttpServletResponse response,
                                                        Object handler) {
        Optional<String> methodOp = getMethod(request, handler);
        if (methodOp.isPresent()) {
            return Optional.of(meterRegistry.counter(String.format("app_requests_resp%d_counts", response.getStatus()),
                    "method", methodOp.get()));
        } else {
            return Optional.empty();
        }
    }

    @Override
    public boolean preHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
        tlTimer.set(System.currentTimeMillis());
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {

    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        // record time
        recordTimeDistribution(request, handler, System.currentTimeMillis() - tlTimer.get());
        tlTimer.remove();

        // total counts
        getCounterOfTotalCounts(request, handler).ifPresent(counter -> counter.increment());
        // different response code count
        getCounterOfRespCodeCounts(request, response, handler).ifPresent(counter -> counter.increment());
        if (ex != null) {
            // exception counts
            getCounterOfExceptionCounts(request, handler).ifPresent(counter -> counter.increment());
        }
    }
}

3 在xml中声明

<mvc:interceptors>
  <bean class="com.mkyong.web.interceptor.MeterInterceptor" />
</mvc:interceptors>

4 启动，测试

mvn jetty:run

访问http://127.0.0.1/spring3，成功后，多访问几次

然后打开jconsole，就能看到统计的jmx了。