Java tutorial
/* * Copyright 2014 MovingBlocks * * 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 org.terasology.world.biomes; import com.google.common.collect.BiMap; import com.google.common.collect.HashBiMap; import com.google.common.collect.ImmutableList; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.terasology.module.ModuleEnvironment; import java.util.Collections; import java.util.List; import java.util.Map; public class BiomeManager implements BiomeRegistry { private static final Logger logger = LoggerFactory.getLogger(BiomeManager.class); // Bi Di map between biome short id and biome private final BiMap<Short, Biome> biomeShortIdMap = HashBiMap.create(); // Map from biome id to biome private final BiMap<String, Biome> biomeIdMap = HashBiMap.create(); /** * Creates a new Biome Manager that auto discovers all biomes in the given environment. */ public BiomeManager(ModuleEnvironment environment) { this(environment, Collections.<String, Short>emptyMap()); } /** * Create a BiomeManager from known state such as a world save, that already contains * a mapping between Biome URIs and their short ids. * * @param knownBiomeIdMap A mapping between Biome URIs (combination of module id + biome id) and * their short ids that are applicable to this world save. */ public BiomeManager(ModuleEnvironment moduleEnvironment, Map<String, Short> knownBiomeIdMap) { for (Class<?> biomeRegistrator : moduleEnvironment.getSubtypesOf(BiomeRegistrator.class)) { BiomeRegistrator registrator; try { registrator = (BiomeRegistrator) biomeRegistrator.newInstance(); } catch (InstantiationException | IllegalAccessException e) { logger.error("Cannot call biome registrator {} because it cannot be instantiated.", biomeRegistrator, e); continue; } registrator.registerBiomes(this); } BiMap<Short, Biome> currentIdMap = HashBiMap.create(biomeShortIdMap); // Make a copy before we start modifying it biomeShortIdMap.clear(); // Always register the unknown biome first, so it gets id 0, which is the default for all chunks registerBiome(UnknownBiome.INSTANCE); for (Map.Entry<String, Short> entry : knownBiomeIdMap.entrySet()) { if (entry.getKey().equals(getUnknownBiome().getId())) { continue; // The unknown biome is handled internally } Biome biome = biomeIdMap.get(entry.getKey()); if (biome == null) { throw new IllegalStateException( "Save game references biome " + entry.getKey() + " which is no " + "longer available."); } if (biomeShortIdMap.put(entry.getValue(), biome) != null) { throw new IllegalStateException("Biome short id " + entry.getValue() + " is present multiple times " + "in the save game (latest is mapped to " + biome.getId() + "."); } logger.info("Restored biome {} with short id {} from save game.", entry.getKey(), entry.getValue()); currentIdMap.values().remove(biome); } // Handle all new biomes that weren't present in the save game for (Biome biome : currentIdMap.values()) { short freeBiomeId = getFreeBiomeId(); biomeShortIdMap.put(freeBiomeId, biome); logger.info("Registered new biome {} with id {} that wasn't present in the save game.", biome.getId(), freeBiomeId); } } public String getBiomeId(Biome biome) { return biomeIdMap.inverse().get(biome); } public void registerBiome(Biome biome) { String fullId = biome.getId(); if (biomeShortIdMap.containsValue(biome)) { throw new IllegalArgumentException("The biome " + fullId + " is already registered."); } if (biomeIdMap.containsKey(fullId)) { throw new IllegalArgumentException("A biome with id " + fullId + " is already registered!"); } short biomeShortId = getFreeBiomeId(); logger.info("Registering biome {} with short id {}.", biome, biomeShortId); biomeShortIdMap.put(biomeShortId, biome); biomeIdMap.put(fullId, biome); } @Override public Biome getBiomeById(String id) { return biomeIdMap.get(id); } @Override public List<Biome> getBiomes() { return ImmutableList.copyOf(biomeIdMap.values()); } /** * Returns a biome with the given id and of the given biome type, only if the biome actually is of the given type. * * @param id * @param biomeClass * @param <T> * @return */ @Override public <T extends Biome> T getBiomeById(String id, Class<T> biomeClass) { Biome biome = getBiomeById(id); if (biome != null) { if (biomeClass.isAssignableFrom(biome.getClass())) { return biomeClass.cast(biome); } } return null; } @Override public <T extends Biome> List<T> getBiomes(Class<T> biomeClass) { ImmutableList.Builder<T> builder = ImmutableList.builder(); for (Biome biome : biomeIdMap.values()) { if (biomeClass.isAssignableFrom(biome.getClass())) { builder.add(biomeClass.cast(biome)); } } return builder.build(); } public Biome getBiomeByShortId(short biomeShortId) { Biome result = biomeShortIdMap.get(biomeShortId); if (result == null) { result = getUnknownBiome(); } return result; } public short getBiomeShortId(Biome biome) { Short result = biomeShortIdMap.inverse().get(biome); if (result == null) { throw new IllegalArgumentException("No short id for biome " + biome + " exists."); } return result; } private short getFreeBiomeId() { short id = 0; while (id < Short.MAX_VALUE) { if (!biomeShortIdMap.containsKey(id)) { return id; } id++; } throw new IllegalStateException("The maximum number of biomes has been reached: " + biomeShortIdMap.size()); } /** * @return A biome that can be used to avoid a null pointer in cases where the real biome is unknown, i.e. * when the chunk has not yet been loaded. * <p/> * TODO: Decide how a caller can determine that he got the unknown biome and not the real one. */ public static Biome getUnknownBiome() { return UnknownBiome.INSTANCE; } }