Java tutorial
/** * This file is part of Graylog. * * Graylog 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. * * Graylog 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 Graylog. If not, see <http://www.gnu.org/licenses/>. */ package org.graylog2.indexer.gson; import com.google.common.collect.ImmutableMap; import com.google.common.reflect.TypeToken; import com.google.gson.Gson; import com.google.gson.JsonArray; import com.google.gson.JsonElement; import com.google.gson.JsonObject; import com.google.gson.JsonPrimitive; import javax.annotation.Nullable; import java.lang.reflect.Type; import java.util.Map; import java.util.Set; public final class GsonUtils { public static final Type MAP_STRING_OBJECT_TYPE = new TypeToken<Map<String, Object>>() { }.getType(); private GsonUtils() { } @Nullable public static JsonObject asJsonObject(JsonElement jsonElement) { return jsonElement instanceof JsonObject ? (JsonObject) jsonElement : null; } @Nullable public static JsonArray asJsonArray(JsonElement jsonElement) { return jsonElement instanceof JsonArray ? (JsonArray) jsonElement : null; } @Nullable public static String asString(JsonElement jsonElement) { return jsonElement instanceof JsonPrimitive ? jsonElement.getAsString() : null; } @Nullable public static Boolean asBoolean(JsonElement jsonElement) { return jsonElement instanceof JsonPrimitive && ((JsonPrimitive) jsonElement).isBoolean() ? jsonElement.getAsBoolean() : null; } @Nullable public static Long asLong(JsonElement jsonElement) { return jsonElement instanceof JsonPrimitive && ((JsonPrimitive) jsonElement).isNumber() ? jsonElement.getAsLong() : null; } @Nullable public static Integer asInteger(JsonElement jsonElement) { return jsonElement instanceof JsonPrimitive && ((JsonPrimitive) jsonElement).isNumber() ? jsonElement.getAsInt() : null; } @Nullable public static Map<String, JsonElement> entrySetAsMap(JsonObject jsonObject) { if (jsonObject == null) { return null; } else { final ImmutableMap.Builder<String, JsonElement> mapBuilder = ImmutableMap.builder(); final Set<Map.Entry<String, JsonElement>> entrySet = jsonObject.entrySet(); for (Map.Entry<String, JsonElement> entry : entrySet) { mapBuilder.put(entry.getKey(), entry.getValue()); } return mapBuilder.build(); } } @Nullable public static Map<String, Object> asMap(Gson gson, JsonObject jsonObject) { return gson.fromJson(jsonObject, MAP_STRING_OBJECT_TYPE); } }