org.eclipse.steady.shared.json.JsonReader Maven / Gradle / Ivy

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Contains class definitions shared between the different Maven modules. They can be classified as follows: Classes for JSON (de)serialization, classes supporting service connectivity, utility classes and classes used to ensure consistency across modules.

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/**
 * This file is part of Eclipse Steady.
 *
 * 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.
 *
 * SPDX-License-Identifier: Apache-2.0
 * SPDX-FileCopyrightText: Copyright (c) 2018-2020 SAP SE or an SAP affiliate company and Eclipse Steady contributors
 */
package org.eclipse.steady.shared.json;

import java.io.IOException;
import java.nio.file.Path;

import org.apache.logging.log4j.Logger;
import org.eclipse.steady.shared.util.FileUtil;

/**
 * Reads a serialized object from disk.
 *
 * @param  type of objects handled by the reader.
 */
public class JsonReader {

  private static final Logger log = org.apache.logging.log4j.LogManager.getLogger();

  private Class clazz;

  /**
   * Constructor for JsonReader.
   *
   * @param _clazz a {@link java.lang.Class} object.
   */
  public JsonReader(Class _clazz) {
    this.clazz = _clazz;
  }

  /**
   * read.
   *
   * @param _path a {@link java.nio.file.Path} object.
   * @return a T object.
   */
  @SuppressWarnings("unchecked")
  public T read(Path _path) {
    T object = null;
    if (FileUtil.isAccessibleFile(_path)) {
      try {
        final String json = FileUtil.readFile(_path);
        object = (T) JacksonUtil.asObject(json, this.clazz);
      } catch (IOException e) {
        log.error("Error reading from file [" + _path + "]: " + e.getMessage(), e);
      } catch (ClassCastException e) {
        log.error("Error reading from file [" + _path + "]: " + e.getMessage(), e);
      } catch (Exception e) {
        log.error("Error reading from file [" + _path + "]: " + e.getMessage(), e);
      }
    }
    return object;
  }
}