Java tutorial
/** * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you 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 org.apache.pulsar.common.stats; import java.util.Collections; import java.util.Map; import com.fasterxml.jackson.databind.annotation.JsonSerialize; import com.google.common.base.Objects; import com.google.common.collect.Maps; /** * WARNING : do not add any getters as the Jackson parser will output that getter. * * You may want to use the ignore annotation provided by jackson parser if you need some getters. * * Dimensions map should be unmodifiable and immutable * * */ public class Metrics { final Map<String, Object> metrics; @JsonSerialize(include = JsonSerialize.Inclusion.NON_EMPTY) final Map<String, String> dimensions; // hide constructor protected Metrics(Map<String, String> unmodifiableDimensionMap) { this.metrics = Maps.newTreeMap(); this.dimensions = unmodifiableDimensionMap; } /** * Creates a metrics object with the dimensions map immutable * * @param application * @param timestamp * @param dimensionsMap * @return */ public static Metrics create(Map<String, String> dimensionMap) { // make the dimensions map unmodifiable and immutable; Map<String, String> map = Maps.newTreeMap(); map.putAll(dimensionMap); return new Metrics(Collections.unmodifiableMap(map)); } public void put(String metricsName, Object value) { metrics.put(metricsName, value); } public Map<String, Object> getMetrics() { return Collections.unmodifiableMap(this.metrics); } public void putAll(Map<String, Object> metrics) { this.metrics.putAll(metrics); } public Map<String, String> getDimensions() { // already unmodifiable return this.dimensions; } public String getDimension(String dimensionName) { return dimensions.get(dimensionName); } @Override public int hashCode() { // the business key will be my metrics dimension [ immutable ] return Objects.hashCode(dimensions); } @Override public boolean equals(Object obj) { // the business key will be my metrics dimension [ immutable ] return (obj instanceof Metrics) && Objects.equal(this.dimensions, ((Metrics) obj).dimensions); } @Override public String toString() { return String.format("dimensions=[%s], metrics=[%s]", dimensions, metrics); } }