code: /*
   * 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 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.apache.commons.io.output;
  
  import java.io.File;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.io.OutputStream;
  import java.io.OutputStreamWriter;
  import java.io.Writer;
  import java.nio.charset.Charset;
  import java.nio.charset.CharsetEncoder;
  
  import org.apache.commons.io.FileUtils;
  import org.apache.commons.io.IOUtils;
  
  /**
   * Writer of files that allows the encoding to be set.
   * <p>
   * This class provides a simple alternative to <code>FileWriter</code>
   * that allows an encoding to be set. Unfortunately, it cannot subclass
   * <code>FileWriter</code>.
   * <p>
   * By default, the file will be overwritten, but this may be changed to append.
   * <p>
   * The encoding must be specified using either the name of the {@link Charset},
   * the {@link Charset}, or a {@link CharsetEncoder}. If the default encoding
   * is required then use the {@link java.io.FileWriter} directly, rather than
   * this implementation.
   * <p>
   * 
   *
   * @since Commons IO 1.4
   * @version $Id: FileWriterWithEncoding.java,v 1.1.2.1.2.1 2011/01/15 20:32:25 caniszczyk Exp $
   */
  public class FileWriterWithEncoding extends Writer {
      // Cannot extend ProxyWriter, as requires writer to be
      // known when super() is called
  
      /** The writer to decorate. */
      private final Writer out;
  
      /**
       * Constructs a FileWriterWithEncoding with a file encoding.
       *
       * @param filename  the name of the file to write to, not null
       * @param encoding  the encoding to use, not null
       * @throws NullPointerException if the file name or encoding is null
       * @throws IOException in case of an I/O error
       */
      public FileWriterWithEncoding(String filename, String encoding) throws IOException {
          this(new File(filename), encoding, false);
      }
  
      /**
       * Constructs a FileWriterWithEncoding with a file encoding.
       *
       * @param filename  the name of the file to write to, not null
       * @param encoding  the encoding to use, not null
       * @param append  true if content should be appended, false to overwrite
       * @throws NullPointerException if the file name or encoding is null
       * @throws IOException in case of an I/O error
       */
      public FileWriterWithEncoding(String filename, String encoding, boolean append) throws IOException {
          this(new File(filename), encoding, append);
      }
  
      /**
       * Constructs a FileWriterWithEncoding with a file encoding.
       *
       * @param filename  the name of the file to write to, not null
       * @param encoding  the encoding to use, not null
       * @throws NullPointerException if the file name or encoding is null
       * @throws IOException in case of an I/O error
       */
      public FileWriterWithEncoding(String filename, Charset encoding) throws IOException {
          this(new File(filename), encoding, false);
      }
  
      /**
       * Constructs a FileWriterWithEncoding with a file encoding.
       *
       * @param filename  the name of the file to write to, not null
       * @param encoding  the encoding to use, not null
       * @param append  true if content should be appended, false to overwrite
       * @throws NullPointerException if the file name or encoding is null
       * @throws IOException in case of an I/O error
       */
      public FileWriterWithEncoding(String filename, Charset encoding, boolean append) throws IOException {
          this(new File(filename), encoding, append);
      }
  
      /**
       * Constructs a FileWriterWithEncoding with a file encoding.
       *
       * @param filename  the name of the file to write to, not null
       * @param encoding  the encoding to use, not null
       * @throws NullPointerException if the file name or encoding is null
       * @throws IOException in case of an I/O error
       */
      public FileWriterWithEncoding(String filename, CharsetEncoder encoding) throws IOException {
          this(new File(filename), encoding, false);
      }
  
      /**
       * Constructs a FileWriterWithEncoding with a file encoding.
       *
       * @param filename  the name of the file to write to, not null
       * @param encoding  the encoding to use, not null
       * @param append  true if content should be appended, false to overwrite
       * @throws NullPointerException if the file name or encoding is null
       * @throws IOException in case of an I/O error
       */
      public FileWriterWithEncoding(String filename, CharsetEncoder encoding, boolean append) throws IOException {
          this(new File(filename), encoding, append);
      }
  
      /**
       * Constructs a FileWriterWithEncoding with a file encoding.
       *
       * @param file  the file to write to, not null
       * @param encoding  the encoding to use, not null
       * @throws NullPointerException if the file or encoding is null
       * @throws IOException in case of an I/O error
       */
      public FileWriterWithEncoding(File file, String encoding) throws IOException {
          this(file, encoding, false);
      }
  
      /**
       * Constructs a FileWriterWithEncoding with a file encoding.
       *
       * @param file  the file to write to, not null
       * @param encoding  the encoding to use, not null
       * @param append  true if content should be appended, false to overwrite
       * @throws NullPointerException if the file or encoding is null
       * @throws IOException in case of an I/O error
       */
      public FileWriterWithEncoding(File file, String encoding, boolean append) throws IOException {
          super();
          this.out = initWriter(file, encoding, append);
      }
  
      /**
       * Constructs a FileWriterWithEncoding with a file encoding.
       *
       * @param file  the file to write to, not null
       * @param encoding  the encoding to use, not null
       * @throws NullPointerException if the file or encoding is null
       * @throws IOException in case of an I/O error
       */
      public FileWriterWithEncoding(File file, Charset encoding) throws IOException {
          this(file, encoding, false);
      }
  
      /**
       * Constructs a FileWriterWithEncoding with a file encoding.
       *
       * @param file  the file to write to, not null
       * @param encoding  the encoding to use, not null
       * @param append  true if content should be appended, false to overwrite
       * @throws NullPointerException if the file or encoding is null
       * @throws IOException in case of an I/O error
       */
      public FileWriterWithEncoding(File file, Charset encoding, boolean append) throws IOException {
          super();
          this.out = initWriter(file, encoding, append);
      }
  
      /**
       * Constructs a FileWriterWithEncoding with a file encoding.
       *
       * @param file  the file to write to, not null
       * @param encoding  the encoding to use, not null
       * @throws NullPointerException if the file or encoding is null
       * @throws IOException in case of an I/O error
       */
      public FileWriterWithEncoding(File file, CharsetEncoder encoding) throws IOException {
          this(file, encoding, false);
      }
  
      /**
       * Constructs a FileWriterWithEncoding with a file encoding.
       *
       * @param file  the file to write to, not null
       * @param encoding  the encoding to use, not null
       * @param append  true if content should be appended, false to overwrite
       * @throws NullPointerException if the file or encoding is null
       * @throws IOException in case of an I/O error
       */
      public FileWriterWithEncoding(File file, CharsetEncoder encoding, boolean append) throws IOException {
          super();
          this.out = initWriter(file, encoding, append);
      }
  
      //-----------------------------------------------------------------------
      /**
       * Initialise the wrapped file writer.
       * Ensure that a cleanup occurs if the writer creation fails.
       *
       * @param file  the file to be accessed
       * @param encoding  the encoding to use - may be Charset, CharsetEncoder or String
       * @param append  true to append
       * @return the initialised writer
       * @throws NullPointerException if the file or encoding is null
       * @throws IOException if an error occurs
       */
       private static Writer initWriter(File file, Object encoding, boolean append) throws IOException {
          if (file == null) {
              throw new NullPointerException("File is missing");
          }
          if (encoding == null) {
              throw new NullPointerException("Encoding is missing");
          }
          boolean fileExistedAlready = file.exists();
          OutputStream stream = null;
          Writer writer = null;
          try {
              stream = new FileOutputStream(file, append);
              if (encoding instanceof Charset) {
                  writer = new OutputStreamWriter(stream, (Charset)encoding);
              } else if (encoding instanceof CharsetEncoder) {
                  writer = new OutputStreamWriter(stream, (CharsetEncoder)encoding);
              } else {
                  writer = new OutputStreamWriter(stream, (String)encoding);
              }
          } catch (IOException ex) {
              IOUtils.closeQuietly(writer);
              IOUtils.closeQuietly(stream);
              if (fileExistedAlready == false) {
                  FileUtils.deleteQuietly(file);
              }
              throw ex;
          } catch (RuntimeException ex) {
              IOUtils.closeQuietly(writer);
              IOUtils.closeQuietly(stream);
              if (fileExistedAlready == false) {
                  FileUtils.deleteQuietly(file);
              }
              throw ex;
          }
          return writer;
      }
  
      //-----------------------------------------------------------------------
      /**
       * Write a character.
       * @param idx the character to write
       * @throws IOException if an I/O error occurs
       */
       @Override
      public void write(int idx) throws IOException {
          out.write(idx);
      }
  
      /**
       * Write the characters from an array.
       * @param chr the characters to write
       * @throws IOException if an I/O error occurs
       */
       @Override
      public void write(char[] chr) throws IOException {
          out.write(chr);
      }
  
      /**
       * Write the specified characters from an array.
       * @param chr the characters to write
       * @param st The start offset
       * @param end The number of characters to write
       * @throws IOException if an I/O error occurs
       */
       @Override
      public void write(char[] chr, int st, int end) throws IOException {
          out.write(chr, st, end);
      }
  
      /**
       * Write the characters from a string.
       * @param str the string to write
       * @throws IOException if an I/O error occurs
       */
       @Override
      public void write(String str) throws IOException {
          out.write(str);
      }
  
      /**
       * Write the specified characters from a string.
       * @param str the string to write
       * @param st The start offset
       * @param end The number of characters to write
       * @throws IOException if an I/O error occurs
       */
       @Override
      public void write(String str, int st, int end) throws IOException {
          out.write(str, st, end);
      }
  
      /**
       * Flush the stream.
       * @throws IOException if an I/O error occurs
       */
       @Override
      public void flush() throws IOException {
          out.flush();
      }
  
      /**
       * Close the stream.
       * @throws IOException if an I/O error occurs
       */
       @Override
      public void close() throws IOException {
          out.close();
      }
  }
  