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Diffstat (limited to 'gson/src/main/java/org/onap/policy/common/gson/MapDoubleAdapterFactory.java')
-rw-r--r-- | gson/src/main/java/org/onap/policy/common/gson/MapDoubleAdapterFactory.java | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/gson/src/main/java/org/onap/policy/common/gson/MapDoubleAdapterFactory.java b/gson/src/main/java/org/onap/policy/common/gson/MapDoubleAdapterFactory.java new file mode 100644 index 00000000..3892a07f --- /dev/null +++ b/gson/src/main/java/org/onap/policy/common/gson/MapDoubleAdapterFactory.java @@ -0,0 +1,152 @@ +/* + * ============LICENSE_START======================================================= + * ONAP + * ================================================================================ + * Copyright (C) 2019 AT&T Intellectual Property. All rights reserved. + * ================================================================================ + * 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. + * ============LICENSE_END========================================================= + */ + +package org.onap.policy.common.gson; + +import com.google.gson.Gson; +import com.google.gson.TypeAdapter; +import com.google.gson.TypeAdapterFactory; +import com.google.gson.reflect.TypeToken; +import com.google.gson.stream.JsonReader; +import com.google.gson.stream.JsonWriter; +import java.io.IOException; +import java.lang.reflect.ParameterizedType; +import java.lang.reflect.Type; +import java.util.Map; +import java.util.Map.Entry; +import java.util.Set; + +/** + * Adapter factory for Map<String,Object>. By default, GSON treats all Objects, that + * are numbers, as Double. This walks the map and converts Doubles to Integer or Long, if + * possible. + */ +public class MapDoubleAdapterFactory implements TypeAdapterFactory { + + @Override + public <T> TypeAdapter<T> create(Gson gson, TypeToken<T> type) { + if (type.getRawType() != Map.class) { + return null; + } + + Type[] actualParams = ((ParameterizedType) type.getType()).getActualTypeArguments(); + + // only supports Map<String,Object> + if (actualParams[0] != String.class || actualParams[1] != Object.class) { + return null; + } + + TypeAdapter<T> delegate = gson.getDelegateAdapter(this, type); + + return new MapAdapter<T>(delegate); + } + + /** + * Type adapter that performs conversion from Double to Integer/Long. + * + * @param <T> type of object on which this works (always Map.class) + */ + private static class MapAdapter<T> extends TypeAdapter<T> { + + /** + * Used to perform conversion between JSON and Map<String,Object>. + */ + private final TypeAdapter<T> delegate; + + /** + * Constructs the object. + * + * @param delegate JSON/Map converter + */ + public MapAdapter(TypeAdapter<T> delegate) { + this.delegate = delegate; + } + + @Override + public void write(JsonWriter out, T value) throws IOException { + delegate.write(out, value); + } + + @Override + public T read(JsonReader in) throws IOException { + T value = delegate.read(in); + + @SuppressWarnings("rawtypes") + Map map = (Map) value; + + convertFromDouble(map); + + return value; + } + + /** + * Performs conversion of all values in a map. + * + * @param map the map whose values are to be converted + */ + @SuppressWarnings("rawtypes") + private void convertFromDouble(Map map) { + + @SuppressWarnings("unchecked") + Set<Entry> set = map.entrySet(); + + for (Entry entry : set) { + convertFromDouble(entry); + } + } + + /** + * Converts an entry's value. If the value is a Map, then it recursively converts + * the entries of the map. + * + * @param entry entry whose value is to be converted + */ + @SuppressWarnings({"unchecked", "rawtypes"}) + private void convertFromDouble(Entry entry) { + Object obj = entry.getValue(); + + if (obj instanceof Map) { + convertFromDouble((Map) obj); + return; + } + + if (!(obj instanceof Double)) { + return; + } + + Double num = (Double) obj; + long longval = num.longValue(); + + if (num.doubleValue() == longval) { + // it's integral - determine if it's an integer or a long + int intval = (int) longval; + + if (intval == longval) { + // it fits in an integer + entry.setValue(intval); + + } else { + // doesn't fit in an integer - must be a long + entry.setValue(longval); + } + } + } + } +} |