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/*
 * 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.commons.text;

import java.util.Map;
import java.util.ResourceBundle;

import org.apache.commons.text.lookup.StringLookup;
import org.apache.commons.text.lookup.StringLookupFactory;

/**
 * Lookup a String key to a String value.
 * 

* This class represents the simplest form of a string to string map. It has a benefit over a map in that it can create * the result on demand based on the key. *

* This class comes complete with various factory methods. If these do not suffice, you can subclass and implement your * own matcher. *

* For example, it would be possible to implement a lookup that used the key as a primary key, and looked up the value * on demand from the database * * @param the type of the values supported by the lookup * @since 1.0 * @deprecated Deprecated as of 1.3, use {@link StringLookupFactory} instead. This class will be removed in 2.0. */ @Deprecated public abstract class StrLookup implements StringLookup { /** * Lookup that always returns null. */ private static final StrLookup NONE_LOOKUP = new MapStrLookup<>(null); /** * Lookup based on system properties. */ private static final StrLookup SYSTEM_PROPERTIES_LOOKUP = new SystemPropertiesStrLookup(); // ----------------------------------------------------------------------- /** * Returns a lookup which always returns null. * * @return a lookup that always returns null, not null */ public static StrLookup noneLookup() { return NONE_LOOKUP; } /** * Returns a new lookup which uses a copy of the current {@link System#getProperties() System properties}. *

* If a security manager blocked access to system properties, then null will be returned from every lookup. *

* If a null key is used, this lookup will throw a NullPointerException. * * @return a lookup using system properties, not null */ public static StrLookup systemPropertiesLookup() { return SYSTEM_PROPERTIES_LOOKUP; } /** * Returns a lookup which looks up values using a map. *

* If the map is null, then null will be returned from every lookup. The map result object is converted to a string * using toString(). * * @param the type of the values supported by the lookup * @param map the map of keys to values, may be null * @return a lookup using the map, not null */ public static StrLookup mapLookup(final Map map) { return new MapStrLookup<>(map); } /** * Returns a lookup which looks up values using a ResourceBundle. *

* If the ResourceBundle is null, then null will be returned from every lookup. The map result object is converted * to a string using toString(). * * @param resourceBundle the map of keys to values, may be null * @return a lookup using the map, not null * @see StringLookupFactory#resourceBundleStringLookup(String) */ public static StrLookup resourceBundleLookup(final ResourceBundle resourceBundle) { return new ResourceBundleLookup(resourceBundle); } // ----------------------------------------------------------------------- /** * Constructor. */ protected StrLookup() { super(); } // ----------------------------------------------------------------------- /** * Lookup implementation that uses a Map. * * @param the type of the values supported by the lookup */ static class MapStrLookup extends StrLookup { /** Map keys are variable names and value. */ private final Map map; /** * Creates a new instance backed by a Map. * * @param map the map of keys to values, may be null */ MapStrLookup(final Map map) { this.map = map; } /** * Looks up a String key to a String value using the map. *

* If the map is null, then null is returned. The map result object is converted to a string using toString(). * * @param key the key to be looked up, may be null * @return the matching value, null if no match */ @Override public String lookup(final String key) { if (map == null) { return null; } final Object obj = map.get(key); if (obj == null) { return null; } return obj.toString(); } @Override public String toString() { return super.toString() + " [map=" + map + "]"; } } // ----------------------------------------------------------------------- /** * Lookup implementation based on a ResourceBundle. */ private static final class ResourceBundleLookup extends StrLookup { /** ResourceBundle keys are variable names and value. */ private final ResourceBundle resourceBundle; /** * Creates a new instance backed by a ResourceBundle. * * @param resourceBundle the ResourceBundle of keys to values, may be null */ private ResourceBundleLookup(final ResourceBundle resourceBundle) { this.resourceBundle = resourceBundle; } @Override public String lookup(final String key) { if (resourceBundle == null || key == null || !resourceBundle.containsKey(key)) { return null; } return resourceBundle.getString(key); } @Override public String toString() { return super.toString() + " [resourceBundle=" + resourceBundle + "]"; } } // ----------------------------------------------------------------------- /** * Lookup implementation based on system properties. */ private static final class SystemPropertiesStrLookup extends StrLookup { /** * {@inheritDoc} This implementation directly accesses system properties. */ @Override public String lookup(final String key) { if (key.length() > 0) { try { return System.getProperty(key); } catch (final SecurityException scex) { // Squelched. All lookup(String) will return null. return null; } } return null; } } }





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