Java/File Input Output/StringWriter

A string writer that is able to write large amounts of data.

 
/**
 * 
 * JFreeReport : a free Java reporting library
 * 
 *
 * Project Info:  http://reporting.pentaho.org/
 *
 * (C) Copyright 2001-2007, by Object Refinery Ltd, Pentaho Corporation and Contributors.
 *
 * This library 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 2.1 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
 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
 * in the United States and other countries.]
 *
 * ------------
 * MemoryStringWriter.java
 * ------------
 * (C) Copyright 2001-2007, by Object Refinery Ltd, Pentaho Corporation and Contributors.
 */
import java.io.IOException;
import java.io.Writer;
/**
 * A string writer that is able to write large amounts of data. The original
 * StringWriter contained in Java doubles its buffersize everytime the buffer
 * overflows. This is nice with small amounts of data, but awfull for huge
 * buffers.
 * 
 * @author Thomas Morgner
 */
public class MemoryStringWriter extends Writer {
  private int bufferIncrement;
  private int cursor;
  private char[] buffer;
  private int maximumBufferIncrement;
  /**
   * Create a new character-stream writer whose critical sections will
   * synchronize on the writer itself.
   */
  public MemoryStringWriter() {
    this(4096);
  }
  /**
   * Create a new character-stream writer whose critical sections will
   * synchronize on the writer itself.
   */
  public MemoryStringWriter(final int bufferSize) {
    this(bufferSize, bufferSize * 4);
  }
  public MemoryStringWriter(final int bufferSize, final int maximumBufferIncrement) {
    this.maximumBufferIncrement = maximumBufferIncrement;
    this.bufferIncrement = bufferSize;
    this.buffer = new char[bufferSize];
  }
  /**
   * Write a portion of an array of characters.
   * 
   * @param cbuf
   *          Array of characters
   * @param off
   *          Offset from which to start writing characters
   * @param len
   *          Number of characters to write
   * @throws java.io.IOException
   *           If an I/O error occurs
   */
  public synchronized void write(final char[] cbuf, final int off, final int len)
      throws IOException {
    if (len < 0) {
      throw new IllegalArgumentException();
    }
    if (off < 0) {
      throw new IndexOutOfBoundsException();
    }
    if (cbuf == null) {
      throw new NullPointerException();
    }
    if ((len + off) > cbuf.length) {
      throw new IndexOutOfBoundsException();
    }
    ensureSize(cursor + len);
    System.arraycopy(cbuf, off, this.buffer, cursor, len);
    cursor += len;
  }
  private void ensureSize(final int size) {
    if (this.buffer.length >= size) {
      return;
    }
    final int computedSize = (int) Math.min((this.buffer.length + 1) * 1.5, this.buffer.length
        + maximumBufferIncrement);
    final int newSize = Math.max(size, computedSize);
    final char[] newBuffer = new char[newSize];
    System.arraycopy(this.buffer, 0, newBuffer, 0, cursor);
    this.buffer = newBuffer;
  }
  /**
   * Flush the stream. If the stream has saved any characters from the various
   * write() methods in a buffer, write them immediately to their intended
   * destination. Then, if that destination is another character or byte stream,
   * flush it. Thus one flush() invocation will flush all the buffers in a chain
   * of Writers and OutputStreams. <p/> If the intended destination of this
   * stream is an abstraction provided by the underlying operating system, for
   * example a file, then flushing the stream guarantees only that bytes
   * previously written to the stream are passed to the operating system for
   * writing; it does not guarantee that they are actually written to a physical
   * device such as a disk drive.
   * 
   * @throws java.io.IOException
   *           If an I/O error occurs
   */
  public void flush() throws IOException {
  }
  /**
   * Close the stream, flushing it first. Once a stream has been closed, further
   * write() or flush() invocations will cause an IOException to be thrown.
   * Closing a previously-closed stream, however, has no effect.
   * 
   * @throws java.io.IOException
   *           If an I/O error occurs
   */
  public void close() throws IOException {
  }
  public int getCursor() {
    return cursor;
  }
  public String toString() {
    return new String(buffer, 0, cursor);
  }
}

String IO

  
import java.io.IOException;
import java.io.StringReader;
import java.io.StringWriter;
public class StringIOApp {
  public static void main(String args[]) throws IOException {
    StringWriter outStream = new StringWriter();
    String s = "This is a test.";
    for (int i = 0; i < s.length(); ++i)
      outStream.write(s.charAt(i));
    System.out.println("outstream: " + outStream);
    System.out.println("size: " + outStream.toString().length());
    StringReader inStream;
    inStream = new StringReader(outStream.toString());
    int ch = 0;
    StringBuffer sb = new StringBuffer("");
    while ((ch = inStream.read()) != -1)
      sb.append((char) ch);
    s = sb.toString();
    System.out.println(s.length() + " characters were read");
    System.out.println("They are: " + s);
  }
}