com.ryantenney.metrics.spring.InjectMetricAnnotationBeanPostProcessor.java Source code

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Here is the source code for com.ryantenney.metrics.spring.InjectMetricAnnotationBeanPostProcessor.java

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/*
 * Copyright 2012 Ryan W Tenney (http://ryan.10e.us)
 *            and Martello Technologies (http://martellotech.com)
 *
 * 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.Field;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.aop.support.AopUtils;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.core.Ordered;
import org.springframework.util.ReflectionUtils;
import org.springframework.util.ReflectionUtils.FieldCallback;

import com.codahale.metrics.Counter;
import com.codahale.metrics.Histogram;
import com.codahale.metrics.Meter;
import com.codahale.metrics.Metric;
import com.codahale.metrics.MetricRegistry;
import com.codahale.metrics.Timer;
import com.ryantenney.metrics.annotation.InjectMetric;

class InjectMetricAnnotationBeanPostProcessor implements BeanPostProcessor, Ordered {

    private static final Logger LOG = LoggerFactory.getLogger(InjectMetricAnnotationBeanPostProcessor.class);

    private static final AnnotationFilter FILTER = new AnnotationFilter(InjectMetric.class);

    private final MetricRegistry metrics;

    public InjectMetricAnnotationBeanPostProcessor(final MetricRegistry metrics) {
        this.metrics = metrics;
    }

    @Override
    public Object postProcessBeforeInitialization(Object bean, String beanName) {
        return bean;
    }

    @Override
    public Object postProcessAfterInitialization(final Object bean, String beanName) {
        final Class<?> targetClass = AopUtils.getTargetClass(bean);

        ReflectionUtils.doWithFields(targetClass, new FieldCallback() {
            @Override
            public void doWith(Field field) throws IllegalAccessException {
                final InjectMetric annotation = field.getAnnotation(InjectMetric.class);
                final String metricName = Util.forInjectMetricField(targetClass, field, annotation);

                final Class<?> type = field.getType();
                Metric metric = null;
                if (Meter.class == type) {
                    metric = metrics.meter(metricName);
                } else if (Timer.class == type) {
                    metric = metrics.timer(metricName);
                } else if (Counter.class == type) {
                    metric = metrics.counter(metricName);
                } else if (Histogram.class == type) {
                    metric = metrics.histogram(metricName);
                } else {
                    throw new IllegalStateException("Cannot inject a metric of type " + type.getCanonicalName());
                }

                ReflectionUtils.makeAccessible(field);
                ReflectionUtils.setField(field, bean, metric);

                LOG.debug("Injected metric {} for field {}.{}", metricName, targetClass.getCanonicalName(),
                        field.getName());
            }
        }, FILTER);

        return bean;
    }

    @Override
    public int getOrder() {
        return LOWEST_PRECEDENCE - 2;
    }

}