Java tutorial
/* * Copyright (c) 2009, SQL Power Group Inc. * * This file is part of SQL Power Library. * * SQL Power Library is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 3 of the License, or * (at your option) any later version. * * SQL Power Library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ package ca.sqlpower.object; import java.util.Collection; import java.util.Collections; import java.util.HashSet; import java.util.Set; import org.apache.commons.collections.map.MultiValueMap; /** * This is a default implementation of a variable resolver the {@link SPObject} * implementations can use. It implements the {@link SPVariableResolver} * and you can use it to store variables. * * <p>It is backed by a MultiMap object. Keep that in mind ;) * * @see {@link SPVariableResolver} * @author Luc Boudreau * */ public class SPSimpleVariableResolver implements SPVariableResolver { protected final MultiValueMap variables = new MultiValueMap(); private String namespace = null; private String userFriendlyName; private final SPObject owner; public SPSimpleVariableResolver(SPObject owner, String namespace, String userFriendlyName) { this(owner, namespace, userFriendlyName, true); } public SPSimpleVariableResolver(SPObject owner, String namespace, String userFriendlyName, boolean register) { this.owner = owner; this.namespace = namespace; this.userFriendlyName = userFriendlyName; if (register) { SPResolverRegistry.register(owner, this); } } /** * This is a hook method that sub classes can override. It gets called * before all lookup operations (resolve, match and resolves). * @param key The key we were asked to lookup info on. */ protected void beforeLookups(String key) { // Nothing to do here. Only sub-classes implement this. } /** * This is a hook method that sub classes can override. It gets called * before the keySet operation. * @param namespace The namespace we were asked to lookup info on. */ protected void beforeKeyLookup(String namespace) { // Nothing to do here. Only sub-classes implement this. } /** * Defines this variable resolver's namespace. * @param namespace The namespace to use. Can be null. */ public void setNamespace(String namespace) { this.namespace = namespace; } /** * Clears all currently stored variables. */ public void clear() { this.variables.clear(); } /** * Closes this resolver and removes it from the registry */ public void cleanup() { SPResolverRegistry.deregister(owner, this); this.clear(); } public void store(String key, Object value) { if (this.namespace != null && SPVariableHelper.getNamespace(key) != null && !this.namespace.equals(SPVariableHelper.getNamespace(key))) { throw new IllegalArgumentException( "Cannot store a namespaced variable of a different namespace than this resolver is configured with."); } this.variables.put(SPVariableHelper.getKey(key), value); } public void update(String key, Object value) { if (this.variables.containsKey(SPVariableHelper.getKey(key))) { this.variables.remove(SPVariableHelper.getKey(key)); } this.variables.put(SPVariableHelper.getKey(key), value); } public void delete(String key) { this.variables.remove(SPVariableHelper.getKey(key)); } public Collection<Object> matches(String key, String partialValue) { // Call the subclass hook. this.beforeLookups(key); String namespace = SPVariableHelper.getNamespace(key); if (this.resolvesNamespace(namespace)) { Set<Object> matches = new HashSet<Object>(); Collection<Object> values = this.resolveCollection(key); for (Object obj : values) { String stringRep = obj.toString(); if (stringRep.startsWith(partialValue)) { matches.add(obj); } } return matches; } return Collections.emptySet(); } public Object resolve(String key) { return this.resolve(key, null); } public Object resolve(String key, Object defaultValue) { // Call the subclass hook. this.beforeLookups(key); String namespace = SPVariableHelper.getNamespace(key); if (this.resolvesNamespace(namespace)) { Collection<Object> value = this.variables.getCollection(SPVariableHelper.getKey(key)); if (value == null || value.size() == 0) { return defaultValue; } else { return value.iterator().next(); } } else { return defaultValue; } } public Collection<Object> resolveCollection(String key) { return this.resolveCollection(key, null); } public Collection<Object> resolveCollection(String key, Object defaultValue) { // Call the subclass hook. this.beforeLookups(key); String namespace = SPVariableHelper.getNamespace(key); if (this.resolvesNamespace(namespace)) { Collection<Object> value = this.variables.getCollection(SPVariableHelper.getKey(key)); if (value != null) { return value; } } return Collections.singleton(defaultValue); } public boolean resolves(String key) { // Call the subclass hook. this.beforeLookups(key); String namespace = SPVariableHelper.getNamespace(key); if (this.resolvesNamespace(namespace)) { return this.variables.containsKey(SPVariableHelper.getKey(key)); } return false; } public boolean resolvesNamespace(String namespace) { if (namespace == null) { return true; } return namespace.equals(this.namespace); } public Collection<String> keySet(String namespace) { // Call the subclass hook. this.beforeKeyLookup(namespace); if (this.resolvesNamespace(namespace)) { if (this.namespace == null) { return this.variables.keySet(); } else { Set<String> keys = new HashSet<String>(); for (Object key : this.variables.keySet()) { keys.add(this.namespace.concat(NAMESPACE_DELIMITER).concat(key.toString())); } return keys; } } return Collections.emptySet(); } public String getNamespace() { return this.namespace; } public String getUserFriendlyName() { return this.userFriendlyName; } public void setUserFriendlyName(String userFriendlyName) { this.userFriendlyName = userFriendlyName; } }