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298 lines
8.7 KiB
Java
298 lines
8.7 KiB
Java
/* CharArrayWriter.java -- Write chars to a buffer
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Copyright (C) 1998, 1999, 2001 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.io;
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/**
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* This class allows data to be written to a char array buffer and
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* and then retrieved by an application. The internal char array
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* buffer is dynamically resized to hold all the data written. Please
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* be aware that writing large amounts to data to this stream will
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* cause large amounts of memory to be allocated.
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* <p>
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* The size of the internal buffer defaults to 32 and it is resized
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* in increments of 1024 chars. This behavior can be over-ridden by using the
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* following two properties:
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* <p>
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* <ul>
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* <li><xmp>gnu.java.io.CharArrayWriter.initialBufferSize</xmp>
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* <li><xmp>gnu.java.io.CharArrayWriter.bufferIncrementSize</xmp>
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* </ul>
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* <p>
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* There is a constructor that specified the initial buffer size and
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* that is the preferred way to set that value because it it portable
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* across all Java class library implementations.
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* <p>
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*
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* @author Aaron M. Renn (arenn@urbanophile.com)
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* @author Tom Tromey <tromey@cygnus.com>
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*/
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public class CharArrayWriter extends Writer
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{
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/**
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* The default initial buffer size
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*/
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private static final int DEFAULT_INITIAL_BUFFER_SIZE = 32;
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/**
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* This method initializes a new <code>CharArrayWriter</code> with
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* the default buffer size of 32 chars. If a different initial
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* buffer size is desired, see the constructor
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* <code>CharArrayWriter(int size)</code>.
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*/
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public CharArrayWriter ()
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{
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this (DEFAULT_INITIAL_BUFFER_SIZE);
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}
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/**
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* This method initializes a new <code>CharArrayWriter</code> with
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* a specified initial buffer size.
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*
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* @param size The initial buffer size in chars
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*/
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public CharArrayWriter (int size)
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{
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super ();
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buf = new char[size];
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}
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/**
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* Closes the stream. This method is guaranteed not to free the contents
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* of the internal buffer, which can still be retrieved.
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*/
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public void close ()
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{
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closed = true;
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}
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/**
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* This method flushes all buffered chars to the stream.
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*/
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public void flush () throws IOException
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{
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synchronized (lock)
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{
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if (closed)
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throw new IOException ("Stream closed");
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}
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}
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/**
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* This method discards all of the chars that have been written to the
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* internal buffer so far by setting the <code>count</code> variable to
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* 0. The internal buffer remains at its currently allocated size.
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*/
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public void reset ()
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{
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synchronized (lock)
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{
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count = 0;
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// Allow this to reopen the stream.
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// FIXME - what does the JDK do?
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closed = false;
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}
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}
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/**
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* This method returns the number of chars that have been written to
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* the buffer so far. This is the same as the value of the protected
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* <code>count</code> variable. If the <code>reset</code> method is
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* called, then this value is reset as well. Note that this method does
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* not return the length of the internal buffer, but only the number
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* of chars that have been written to it.
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*
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* @return The number of chars in the internal buffer
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*
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* @see reset
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*/
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public int size ()
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{
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return count;
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}
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/**
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* This method returns a char array containing the chars that have been
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* written to this stream so far. This array is a copy of the valid
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* chars in the internal buffer and its length is equal to the number of
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* valid chars, not necessarily to the the length of the current
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* internal buffer. Note that since this method allocates a new array,
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* it should be used with caution when the internal buffer is very large.
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*/
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public char[] toCharArray ()
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{
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synchronized (lock)
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{
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char[] nc = new char[count];
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System.arraycopy(buf, 0, nc, 0, count);
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return nc;
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}
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}
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/**
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* Returns the chars in the internal array as a <code>String</code>. The
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* chars in the buffer are converted to characters using the system default
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* encoding. There is an overloaded <code>toString()</code> method that
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* allows an application specified character encoding to be used.
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*
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* @return A <code>String</code> containing the data written to this
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* stream so far
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*/
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public String toString ()
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{
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synchronized (lock)
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{
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return new String (buf, 0, count);
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}
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}
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/**
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* This method writes the writes the specified char into the internal
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* buffer.
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*
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* @param oneChar The char to be read passed as an int
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*/
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public void write (int oneChar) throws IOException
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{
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synchronized (lock)
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{
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if (closed)
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throw new IOException ("Stream closed");
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resize (1);
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buf[count++] = (char) oneChar;
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}
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}
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/**
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* This method writes <code>len</code> chars from the passed in array
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* <code>buf</code> starting at index <code>offset</code> into that buffer
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*
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* @param buffer The char array to write data from
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* @param offset The index into the buffer to start writing data from
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* @param len The number of chars to write
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*/
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public void write (char[] buffer, int offset, int len) throws IOException
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{
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synchronized (lock)
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{
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if (closed)
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throw new IOException ("Stream closed");
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if (len >= 0)
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resize (len);
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System.arraycopy(buffer, offset, buf, count, len);
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count += len;
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}
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}
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/**
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* This method writes <code>len</code> chars from the passed in
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* <code>String</code> <code>buf</code> starting at index
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* <code>offset</code> into the internal buffer.
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*
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* @param str The <code>String</code> to write data from
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* @param offset The index into the string to start writing data from
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* @param len The number of chars to write
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*/
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public void write (String str, int offset, int len) throws IOException
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{
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synchronized (lock)
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{
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if (closed)
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throw new IOException ("Stream closed");
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if (len >= 0)
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resize (len);
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str.getChars(offset, offset + len, buf, count);
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count += len;
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}
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}
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/**
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* This method writes all the chars that have been written to this stream
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* from the internal buffer to the specified <code>Writer</code>.
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*
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* @param out The <code>Writer</code> to write to
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*
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* @exception IOException If an error occurs
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*/
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public void writeTo (Writer out) throws IOException
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{
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synchronized (lock)
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{
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out.write(buf, 0, count);
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}
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}
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/**
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* This private method makes the buffer bigger when we run out of room
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* by allocating a larger buffer and copying the valid chars from the
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* old array into it. This is obviously slow and should be avoided by
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* application programmers by setting their initial buffer size big
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* enough to hold everything if possible.
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*/
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private final void resize (int len)
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{
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if (count + len >= buf.length)
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{
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int newlen = buf.length * 2;
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if (count + len > newlen)
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newlen = count + len;
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char[] newbuf = new char[newlen];
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System.arraycopy(buf, 0, newbuf, 0, count);
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buf = newbuf;
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}
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}
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/**
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* The internal buffer where the data written is stored
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*/
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protected char[] buf;
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/**
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* The number of chars that have been written to the buffer
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*/
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protected int count;
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/**
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* True if the stream has been closed.
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*/
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private boolean closed;
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}
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