com.google.firebase.database.util.JsonMapper Maven / Gradle / Ivy

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/*
 * Copyright 2017 Google Inc.
 *
 * 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.
 */

package com.google.firebase.database.util;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonSyntaxException;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonToken;
import java.io.IOException;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * Helper class to convert from/to JSON strings. TODO: This class should ideally not live in
 * firebase-database-connection, but it's required by both firebase-database and
 * firebase-database-connection, so leave it here for now.
 */
public class JsonMapper {

  private static final Gson GSON = new GsonBuilder().serializeNulls().create();

  public static String serializeJson(Object object) throws IOException {
    try {
      return GSON.toJson(object);
    } catch (JsonSyntaxException e) {
      throw new IOException(e);
    }
  }

  public static Map parseJson(String json) throws IOException {
    try {
      JsonReader jsonReader = new JsonReader(new StringReader(json));
      return unwrapJsonObject(jsonReader);
    } catch (IllegalStateException | JsonSyntaxException e) {
      throw new IOException(e);
    }
  }

  public static Object parseJsonValue(String json) throws IOException {
    try {
      JsonReader jsonReader = new JsonReader(new StringReader(json));
      jsonReader.setLenient(true);
      return unwrapJson(jsonReader);
    } catch (IllegalStateException | JsonSyntaxException e) {
      throw new IOException(e);
    }
  }

  private static Map unwrapJsonObject(JsonReader jsonReader) throws IOException {
    Map map = new HashMap<>();
    jsonReader.beginObject();
    while (jsonReader.peek() != JsonToken.END_OBJECT) {
      String key = jsonReader.nextName();
      map.put(key, unwrapJson(jsonReader));
    }
    jsonReader.endObject();
    return map;
  }

  private static List