Java tutorial
/** * Copyright (C) 2012 Ryan W Tenney (ryan@10e.us) * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.ryantenney.metrics.spring; import java.lang.reflect.Method; import org.springframework.core.Ordered; import org.springframework.util.ReflectionUtils; import com.codahale.metrics.MetricRegistry; import com.codahale.metrics.annotation.Gauge; import static com.ryantenney.metrics.spring.AnnotationFilter.INSTANCE_METHODS; class GaugeMethodAnnotationBeanPostProcessor extends AbstractAnnotationBeanPostProcessor implements Ordered { private static final AnnotationFilter FILTER = new AnnotationFilter(Gauge.class, INSTANCE_METHODS); private final MetricRegistry metrics; public GaugeMethodAnnotationBeanPostProcessor(final MetricRegistry metrics) { super(Members.ALL, Phase.POST_INIT, FILTER); this.metrics = metrics; } @Override protected void withMethod(final Object bean, String beanName, Class<?> targetClass, final Method method) { if (method.getParameterTypes().length > 0) { throw new IllegalStateException( "Method " + method.getName() + " is annotated with @Gauge but requires parameters."); } final Gauge annotation = method.getAnnotation(Gauge.class); final String metricName = Util.forGauge(targetClass, method, annotation); metrics.register(metricName, new com.codahale.metrics.Gauge<Object>() { @Override public Object getValue() { return ReflectionUtils.invokeMethod(method, bean); } }); LOG.debug("Created gauge {} for method {}.{}", metricName, targetClass.getCanonicalName(), method.getName()); } @Override public int getOrder() { return LOWEST_PRECEDENCE; } }