/* | |
* 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. | |
* <p> | |
* 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. | |
* <p> | |
* This class comes complete with various factory methods. If these do not suffice, you can subclass and implement your | |
* own matcher. | |
* <p> | |
* 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 <V> 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<V> implements StringLookup { | |
/** | |
* Lookup that always returns null. | |
*/ | |
private static final StrLookup<String> NONE_LOOKUP = new MapStrLookup<>(null); | |
/** | |
* Lookup based on system properties. | |
*/ | |
private static final StrLookup<String> 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}. | |
* <p> | |
* If a security manager blocked access to system properties, then null will be returned from every lookup. | |
* <p> | |
* If a null key is used, this lookup will throw a NullPointerException. | |
* | |
* @return a lookup using system properties, not null | |
*/ | |
public static StrLookup<String> systemPropertiesLookup() { | |
return SYSTEM_PROPERTIES_LOOKUP; | |
} | |
/** | |
* Returns a lookup which looks up values using a map. | |
* <p> | |
* 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 <V> 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 <V> StrLookup<V> mapLookup(final Map<String, V> map) { | |
return new MapStrLookup<>(map); | |
} | |
/** | |
* Returns a lookup which looks up values using a ResourceBundle. | |
* <p> | |
* 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 | |
*/ | |
public static StrLookup<String> resourceBundleLookup(final ResourceBundle resourceBundle) { | |
return new ResourceBundleLookup(resourceBundle); | |
} | |
// ----------------------------------------------------------------------- | |
/** | |
* Constructor. | |
*/ | |
protected StrLookup() { | |
super(); | |
} | |
// ----------------------------------------------------------------------- | |
/** | |
* Lookup implementation that uses a Map. | |
* | |
* @param <V> the type of the values supported by the lookup | |
*/ | |
static class MapStrLookup<V> extends StrLookup<V> { | |
/** Map keys are variable names and value. */ | |
private final Map<String, V> map; | |
/** | |
* Creates a new instance backed by a Map. | |
* | |
* @param map the map of keys to values, may be null | |
*/ | |
MapStrLookup(final Map<String, V> map) { | |
this.map = map; | |
} | |
/** | |
* Looks up a String key to a String value using the map. | |
* <p> | |
* 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<String> { | |
/** 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<String> { | |
/** | |
* {@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; | |
} | |
} | |
} |