FileReaderWriter.java

/*
 * ******************************************************************************
 * MontiCore Language Workbench
 * Copyright (c) 2015, MontiCore, All rights reserved.
 *
 * This project is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3.0 of the License, or (at your option) any later version.
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this project. If not, see <http://www.gnu.org/licenses/>.
 * ******************************************************************************
 */

package de.monticore.io;

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

import org.apache.commons.io.FileUtils;

import com.google.common.base.Charsets;

import de.se_rwth.commons.logging.Log;

/**
 * This class handles all I/O commands in Monticore.
 * <p>
 * Important conventions: File locations are always encoded as Path objects.
 * When creating Path objects please make use of the {@link Path#resolve} method
 * whenever applicable. This convention extends beyond the FileHandler. Do
 * <b>not</b> exchange information between classes using String literals or File
 * objects. Doing so within classes is permitted, though discouraged.<br>
 * Failure to adhere to such a convention has caused innumerable trivial bugs in
 * past implementations.
 * <p>
 * This class uses UTF_8 encoding per default.
 * 
 * @author Sebastian Oberhoff
 */
public class FileReaderWriter {
  
  private Charset charset;
  
  /**
   * Sets the encoding for all subsequent operations until another encoding is
   * assigned.
   * 
   * @param charset The encoding to be used
   */
  public void setCharset(Charset charset) {
    this.charset = charset;
  }
  
  /**
   * Uses the default encoding UTF_8;
   */
  public FileReaderWriter() {
    this.charset = Charsets.UTF_8;
  }
  
  /**
   * @param charset The initial encoding to be used until another encoding is
   * assigned.
   * @see #setCharset
   */
  public FileReaderWriter(Charset charset) {
    this.charset = charset;
  }
  
  /**
   * Writes a String to a file using the specified encoding.
   * 
   * @param targetPath The location of the file to be written to.
   * @param content The String that's supposed to be written into the file
   * @see #setCharset(Charset)
   */
  public void storeInFile(Path targetPath, String content) {
    try {
      FileUtils.write(targetPath.toFile(), content, this.charset);
    }
    catch (IOException e) {
      Log.error("0xA1023 IOException occured.", e);
      Log.debug("IOException occured while trying to write to the File " + targetPath + ".", e,
          this.getClass().getName());
    }
  }
  
  /**
   * Reads the String content from a file using the specified encoding.
   * 
   * @param sourcePath The absolute location (fully specifies the filename) of
   * the file to be read
   * @return The String content of the file
   * @see #setCharset(Charset)
   */
  public String readFromFile(Path sourcePath) {
    String content = null;
    try {
      content = FileUtils.readFileToString(sourcePath.toFile(), this.charset);
    }
    catch (IOException e) {
      Log.error("0xA1024 IOException occured.", e);
      Log.debug("IOException while trying to read the content of " + sourcePath
          + ".", e, this.getClass().getName());
    }
    Log.errorIfNull(content);
    return content;
  }
  
}