001/* 002 * Units of Measurement Reference Implementation 003 * Copyright (c) 2005-2020, Units of Measurement project. 004 * 005 * All rights reserved. 006 * 007 * Redistribution and use in source and binary forms, with or without modification, 008 * are permitted provided that the following conditions are met: 009 * 010 * 1. Redistributions of source code must retain the above copyright notice, 011 * this list of conditions and the following disclaimer. 012 * 013 * 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions 014 * and the following disclaimer in the documentation and/or other materials provided with the distribution. 015 * 016 * 3. Neither the name of JSR-385, Indriya nor the names of their contributors may be used to endorse or promote products 017 * derived from this software without specific prior written permission. 018 * 019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" 020 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, 021 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 022 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE 023 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 024 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 025 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 026 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 027 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, 028 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 029 */ 030package tech.units.indriya.spi; 031 032import javax.measure.Quantity; 033import javax.measure.spi.FormatService; 034import javax.measure.spi.QuantityFactory; 035import javax.measure.spi.ServiceProvider; 036import javax.measure.spi.SystemOfUnitsService; 037import javax.measure.spi.UnitFormatService; 038 039import tech.units.indriya.quantity.DefaultQuantityFactory; 040 041import java.util.ArrayList; 042import java.util.Collections; 043import java.util.Comparator; 044import java.util.List; 045import java.util.Map; 046import java.util.ServiceLoader; 047import java.util.concurrent.ConcurrentHashMap; 048import java.util.logging.Level; 049import java.util.logging.Logger; 050 051/** 052 * This class extends the {@link javax.measure.spi.ServiceProvider} class and hereby uses the JDK {@link java.util.ServiceLoader} to load the required 053 * services. 054 * 055 * @author Werner Keil 056 * @version 1.1 057 * @since 2.0 058 */ 059public abstract class AbstractServiceProvider extends ServiceProvider implements Comparable<ServiceProvider> { 060 061 /** 062 * List of services loaded, per class. 063 */ 064 @SuppressWarnings("rawtypes") 065 private final Map<Class, List<Object>> servicesLoaded = new ConcurrentHashMap<>(); 066 067 private static final Comparator<Object> SERVICE_COMPARATOR = AbstractServiceProvider::compareServices; 068 069 @SuppressWarnings("rawtypes") 070 private final Map<Class, QuantityFactory> QUANTITY_FACTORIES = new ConcurrentHashMap<>(); 071 072 /** 073 * Loads and registers services. 074 * 075 * @param serviceType 076 * The service type. 077 * @param <T> 078 * the concrete type. 079 * @return the items found, never {@code null}. 080 */ 081 protected <T> List<T> getServices(final Class<T> serviceType) { 082 @SuppressWarnings("unchecked") 083 List<T> found = (List<T>) servicesLoaded.get(serviceType); 084 if (found != null) { 085 return found; 086 } 087 return loadServices(serviceType); 088 } 089 090 protected <T> T getService(Class<T> serviceType) { 091 List<T> services = getServices(serviceType); 092 if (services.isEmpty()) { 093 return null; 094 } 095 return services.get(0); 096 } 097 098 private static int compareServices(Object o1, Object o2) { 099 int prio1 = 0; 100 int prio2 = 0; 101 if (prio1 < prio2) { 102 return 1; 103 } 104 if (prio2 < prio1) { 105 return -1; 106 } 107 return o2.getClass().getSimpleName().compareTo(o1.getClass().getSimpleName()); 108 } 109 110 /** 111 * Loads and registers services. 112 * 113 * @param serviceType 114 * The service type. 115 * @param <T> 116 * the concrete type. 117 * @return the items found, never {@code null}. 118 */ 119 private <T> List<T> loadServices(final Class<T> serviceType) { 120 List<T> services = new ArrayList<>(); 121 try { 122 for (T t : ServiceLoader.load(serviceType)) { 123 services.add(t); 124 } 125 Collections.sort(services, SERVICE_COMPARATOR); 126 @SuppressWarnings("unchecked") 127 final List<T> previousServices = (List<T>) servicesLoaded.putIfAbsent(serviceType, (List<Object>) services); 128 return Collections.unmodifiableList(previousServices != null ? previousServices : services); 129 } catch (Exception e) { 130 Logger.getLogger(AbstractServiceProvider.class.getName()).log(Level.WARNING, "Error loading services of type " + serviceType, e); 131 Collections.sort(services, SERVICE_COMPARATOR); 132 return services; 133 } 134 } 135 136 @Override 137 public int compareTo(ServiceProvider o) { 138 return Integer.compare(getPriority(), o.getPriority()); 139 } 140 141 @Override 142 public SystemOfUnitsService getSystemOfUnitsService() { 143 return getService(SystemOfUnitsService.class); 144 } 145 146 @Override 147 public UnitFormatService getUnitFormatService() { 148 return getService(UnitFormatService.class); 149 } 150 151 @Override 152 public FormatService getFormatService() { 153 return getService(FormatService.class); 154 } 155 156 /** 157 * Return a factory for this quantity 158 * 159 * @param quantity 160 * the quantity type 161 * @return the {@link QuantityFactory} 162 * @throws NullPointerException 163 */ 164 @Override 165 @SuppressWarnings("unchecked") 166 public final <Q extends Quantity<Q>> QuantityFactory<Q> getQuantityFactory(Class<Q> quantity) { 167 if (quantity == null) 168 throw new NullPointerException(); 169 if (!QUANTITY_FACTORIES.containsKey(quantity)) { 170 synchronized (QUANTITY_FACTORIES) { 171 QUANTITY_FACTORIES.put(quantity, DefaultQuantityFactory.getInstance(quantity)); 172 } 173 } 174 return QUANTITY_FACTORIES.get(quantity); 175 } 176 177 @Override 178 public abstract String toString(); 179}