org.apache.solr.util.DistanceUnits Maven / Gradle / Ivy
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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.solr.util;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import com.google.common.collect.ImmutableMap;
import org.locationtech.spatial4j.distance.DistanceUtils;
import org.apache.solr.schema.AbstractSpatialFieldType;
/**
* Used with a spatial field type for all distance measurements.
*
* @see AbstractSpatialFieldType
*/
public class DistanceUnits {
public final static String KILOMETERS_PARAM = "kilometers";
public final static String MILES_PARAM = "miles";
public final static String DEGREES_PARAM = "degrees";
// Singleton distance units instances
public final static DistanceUnits KILOMETERS = new DistanceUnits(KILOMETERS_PARAM, DistanceUtils.EARTH_MEAN_RADIUS_KM,
DistanceUtils.KM_TO_DEG);
public final static DistanceUnits MILES = new DistanceUnits(MILES_PARAM, DistanceUtils.EARTH_MEAN_RADIUS_MI,
DistanceUtils.MILES_TO_KM * DistanceUtils.KM_TO_DEG);
public final static DistanceUnits DEGREES = new DistanceUnits(DEGREES_PARAM, 180.0/Math.PI, 1.0);
//volatile so other threads see when we replace when copy-on-write
private static volatile Map instances = ImmutableMap.of(
KILOMETERS_PARAM, KILOMETERS,
MILES_PARAM, MILES,
DEGREES_PARAM, DEGREES);
private final String stringIdentifier;
private final double earthRadius;
private final double multiplierThisToDegrees;
private final double multiplierDegreesToThis;
private DistanceUnits(String str, double earthRadius, double multiplierThisToDegrees) {
this.stringIdentifier = str;
this.earthRadius = earthRadius;
this.multiplierThisToDegrees = multiplierThisToDegrees;
this.multiplierDegreesToThis = 1.0 / multiplierThisToDegrees;
}
/**
* Parses a string representation of distance units and returns its implementing class instance.
* Preferred way to parse a DistanceUnits would be to use {@link AbstractSpatialFieldType#parseDistanceUnits(String)},
* since it will default to one defined on the field type if the string is null.
*
* @param str String representation of distance units, e.g. "kilometers", "miles" etc. (null ok)
* @return an instance of the concrete DistanceUnits, null if not found.
*/
public static DistanceUnits valueOf(String str) {
return instances.get(str);
}
public static Set getSupportedUnits() {
return instances.keySet();
}
/**
*
* @return Radius of the earth in this distance units
*/
public double getEarthRadius() {
return earthRadius;
}
/**
*
* @return multiplier needed to convert a distance in current units to degrees
*/
public double multiplierFromThisUnitToDegrees() {
return multiplierThisToDegrees;
}
/**
*
* @return multiplier needed to convert a distance in degrees to current units
*/
public double multiplierFromDegreesToThisUnit() {
return multiplierDegreesToThis;
}
/**
*
* @return the string identifier associated with this units instance
*/
public String getStringIdentifier() {
return stringIdentifier;
}
/**
* Custom distance units can be supplied using this method. It's thread-safe.
*
* @param strId string identifier for the units
* @param earthRadius radius of earth in supplied units
* @param multiplierThisToDegrees multiplier to convert to degrees
*/
public static synchronized void addUnits(String strId, double earthRadius, double multiplierThisToDegrees) {
//copy-on-write.
Map map = new HashMap(instances);
map.put(strId, new DistanceUnits(strId, earthRadius, multiplierThisToDegrees));
instances = ImmutableMap.copyOf(map);
}
@Override
public String toString() {
return getStringIdentifier();
}
}