FileUtils.java

/*
 * Copyright 2014-2016 CyberVision, 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 org.kaaproject.kaa.server.common.utils;

import org.apache.commons.io.IOUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Properties;

public class FileUtils {

  private static final Logger LOG = LoggerFactory.getLogger(FileUtils.class);

  private FileUtils() {
  }

  /**
   * Read resource.
   *
   * @param resource the resource
   * @return the string
   * @throws IOException Signals that an I/O exception has occurred.
   */
  public static String readResource(String resource) throws IOException {
    String result = null;
    try {
      StringBuffer fileData = new StringBuffer();
      InputStream input = Thread.currentThread().getContextClassLoader()
          .getResourceAsStream(resource);
      BufferedReader reader = new BufferedReader(new InputStreamReader(input));
      char[] buf = new char[1024];
      int numRead = 0;
      while ((numRead = reader.read(buf)) != -1) {
        String readData = String.valueOf(buf, 0, numRead);
        fileData.append(readData);
      }
      reader.close();
      result = fileData.toString();
    } catch (IOException exception) {
      LOG.error("Unable to read from specified resource '"
          + resource + "'! Error: " + exception.getMessage(), exception);
      throw exception;
    }
    return result;
  }

  /**
   * Read resource bytes.
   *
   * @param resource the resource
   * @return the byte array
   * @throws IOException Signals that an I/O exception has occurred.
   */
  public static byte[] readResourceBytes(String resource) throws IOException {
    try (InputStream input = Thread.currentThread().getContextClassLoader()
        .getResourceAsStream(resource)) {
      return IOUtils.toByteArray(input);
    } catch (IOException exception) {
      LOG.error("Unable to read from specified resource '"
          + resource + "'! Error: " + exception.getMessage(), exception);
      throw exception;
    }
  }

  /**
   * Read resource peroperties.
   *
   * @param resource the resource
   * @return the properties
   * @throws IOException Signals that an I/O exception has occurred.
   */
  public static Properties readResourceProperties(String resource) throws IOException {
    Properties result = null;
    try {
      InputStream input = Thread.currentThread().getContextClassLoader()
          .getResourceAsStream(resource);
      result = new Properties();
      result.load(input);
      input.close();
    } catch (IOException exception) {
      LOG.error("Unable to read from specified resource '"
          + resource + "'! Error: " + exception.getMessage(), exception);
      throw exception;
    }
    return result;
  }
}