JsonUtil.java

/*
 * 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
 *
 *   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.streams.jackson;

import com.fasterxml.jackson.core.JsonFactory;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.fasterxml.jackson.databind.node.ObjectNode;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
import java.util.List;

/**
 * JSON utilities.
 */
public class JsonUtil {

  private JsonUtil() {}

  private static ObjectMapper mapper = StreamsJacksonMapper.getInstance();
  private static JsonFactory factory = mapper.getFactory();

  public static JsonNode jsonToJsonNode(String json) {
    JsonNode node;
    try {
      JsonParser jp = factory.createJsonParser(json);
      node = mapper.readTree(jp);
    } catch (IOException e) {
      throw new RuntimeException("IO exception while reading JSON", e);
    }
    return node;
  }

  public static String jsonNodeToJson(JsonNode node) {
    try {
      return mapper.writeValueAsString(node);
    } catch (JsonProcessingException e) {
      throw new RuntimeException("IO exception while writing JSON", e);
    }
  }

  public static <T> T jsonToObject(String json, Class<T> clazz) {
    try {
      return mapper.readValue(json, clazz);
    } catch (IOException e) {
      throw new RuntimeException("Could not map to object");
    }
  }

  public static <T> T jsonNodeToObject(JsonNode node, Class<T> clazz) {
    return mapper.convertValue(node, clazz);
  }

  public static <T> JsonNode objectToJsonNode(T obj) {
    return mapper.valueToTree(obj);
  }

  public static <T> List<T> jsoNodeToList(JsonNode node, Class<T> clazz) {
    return mapper.convertValue(node, new TypeReference<List<T>>() {});
  }

  public static <T> String objectToJson(T object) {
    try {
      return mapper.writeValueAsString(object);
    } catch (IOException e) {
      throw new RuntimeException("Could not map to object");
    }
  }

  public static <T> T getObjFromFile(String filePath, Class<T> clazz) {
    return jsonNodeToObject(getFromFile(filePath), clazz);
  }

  public static JsonNode getFromFile(String filePath) {
    JsonFactory factory = mapper.getFactory(); // since 2.1 use mapper.getFactory() instead

    JsonNode node;
    try {
      InputStream stream = getStreamForLocation(filePath);
      JsonParser jp = factory.createParser(stream);
      node = mapper.readTree(jp);
    } catch (IOException e) {
      throw new RuntimeException(e);
    }
    return node;
  }

  private static InputStream getStreamForLocation(String filePath) throws FileNotFoundException {
    InputStream stream;
    if(filePath.startsWith("file:///")) {
      stream = new FileInputStream(filePath.replace("file:///", ""));
    } else if(filePath.startsWith("file:") || filePath.startsWith("/")) {
      stream = new FileInputStream(filePath.replace("file:", ""));
    } else {
      //Assume classpath
      stream = JsonUtil.class.getClassLoader().getResourceAsStream(filePath.replace("classpath:", ""));
    }

    return stream;
  }

  /**
   * Creates an empty array if missing
   * @param node object to create the array within
   * @param field location to create the array
   * @return the Map representing the extensions property
   */
  public static ArrayNode ensureArray(ObjectNode node, String field) {
    String[] path = field.split(".");
    ObjectNode current = node;
    ArrayNode result;
    for( int i = 0; i < path.length; i++) {
      current = ensureObject((ObjectNode) node.get(path[i]), path[i]);
    }
    if (current.get(field) == null)
      current.put(field, mapper.createArrayNode());
    result = (ArrayNode) node.get(field);
    return result;
  }

  /**
   * Creates an empty array if missing
   * @param node objectnode to create the object within
   * @param field location to create the object
   * @return the Map representing the extensions property
   */
  public static ObjectNode ensureObject(ObjectNode node, String field) {
    String[] path = field.split(".");
    ObjectNode current = node;
    ObjectNode result;
    for( int i = 0; i < path.length; i++) {
      if (node.get(field) == null)
        node.put(field, mapper.createObjectNode());
      current = (ObjectNode) node.get(field);
    }
    result = ensureObject((ObjectNode) node.get(path[path.length]), String.join(".", Arrays.copyOfRange(path, 1, path.length)));
    return result;
  }

}