| /* BufferedWriter.java -- Buffer output into large blocks before writing |
| Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2, or (at your option) |
| any later version. |
| |
| GNU Classpath 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 |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package java.io; |
| |
| /* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3 |
| * "The Java Language Specification", ISBN 0-201-63451-1 |
| * Status: Complete to version 1.1. |
| */ |
| |
| /** |
| * This class accumulates chars written in a buffer instead of immediately |
| * writing the data to the underlying output sink. The chars are instead |
| * as one large block when the buffer is filled, or when the stream is |
| * closed or explicitly flushed. This mode operation can provide a more |
| * efficient mechanism for writing versus doing numerous small unbuffered |
| * writes. |
| * |
| * @author Aaron M. Renn (arenn@urbanophile.com) |
| * @author Tom Tromey (tromey@cygnus.com) |
| * @date September 25, 1998 |
| */ |
| public class BufferedWriter extends Writer |
| { |
| /** |
| * This is the default buffer size |
| */ |
| private static final int DEFAULT_BUFFER_SIZE = 8192; |
| |
| /** |
| * This is the underlying <code>Writer</code> to which this object |
| * sends its output. |
| */ |
| private Writer out; |
| |
| /** |
| * This is the internal char array used for buffering output before |
| * writing it. |
| */ |
| char[] buffer; |
| |
| /** |
| * This is the number of chars that are currently in the buffer and |
| * are waiting to be written to the underlying stream. It always points to |
| * the index into the buffer where the next char of data will be stored |
| */ |
| int count; |
| |
| /** |
| * This method initializes a new <code>BufferedWriter</code> instance |
| * that will write to the specified subordinate <code>Writer</code> |
| * and which will use a default buffer size of 8192 chars. |
| * |
| * @param out The underlying <code>Writer</code> to write data to |
| */ |
| public BufferedWriter (Writer out) |
| { |
| this (out, DEFAULT_BUFFER_SIZE); |
| } |
| |
| /** |
| * This method initializes a new <code>BufferedWriter</code> instance |
| * that will write to the specified subordinate <code>Writer</code> |
| * and which will use the specified buffer size |
| * |
| * @param out The underlying <code>Writer</code> to write data to |
| * @param size The size of the internal buffer |
| */ |
| public BufferedWriter (Writer out, int size) |
| { |
| super(out.lock); |
| this.out = out; |
| this.buffer = new char[size]; |
| this.count = 0; |
| } |
| |
| /** |
| * This method flushes any remaining buffered chars then closes the |
| * underlying output stream. Any further attempts to write to this stream |
| * may throw an exception |
| * |
| * @exception IOException If an error occurs. |
| */ |
| public void close () throws IOException |
| { |
| synchronized (lock) |
| { |
| // It is safe to call localFlush even if the stream is already |
| // closed. |
| localFlush (); |
| out.close(); |
| buffer = null; |
| } |
| } |
| |
| /** |
| * This method causes any currently buffered chars to be immediately |
| * written to the underlying output stream. |
| * |
| * @exception IOException If an error occurs |
| */ |
| public void flush () throws IOException |
| { |
| synchronized (lock) |
| { |
| if (buffer == null) |
| throw new IOException ("Stream closed"); |
| localFlush (); |
| out.flush(); |
| } |
| } |
| |
| /** |
| * This method writes out a system depedent line separator sequence. The |
| * actual value written is detemined from the <xmp>line.separator</xmp> |
| * system property. |
| * |
| * @exception IOException If an error occurs |
| */ |
| public void newLine () throws IOException |
| { |
| write (System.getProperty("line.separator")); |
| } |
| |
| /** |
| * This method writes a single char of data. This will be written to the |
| * buffer instead of the underlying data source. However, if the buffer |
| * is filled as a result of this write request, it will be flushed to the |
| * underlying output stream. |
| * |
| * @param oneChar The char of data to be written, passed as an int |
| * |
| * @exception IOException If an error occurs |
| */ |
| public void write (int oneChar) throws IOException |
| { |
| synchronized (lock) |
| { |
| if (buffer == null) |
| throw new IOException ("Stream closed"); |
| buffer[count++] = (char) oneChar; |
| if (count == buffer.length) |
| localFlush (); |
| } |
| } |
| |
| /** |
| * This method writes <code>len</code> chars from the char array |
| * <code>buf</code> starting at position <code>offset</code> in the buffer. |
| * These chars will be written to the internal buffer. However, if this |
| * write operation fills the buffer, the buffer will be flushed to the |
| * underlying output stream. |
| * |
| * @param buf The array of chars to write. |
| * @param offset The index into the char array to start writing from. |
| * @param len The number of chars to write. |
| * |
| * @exception IOException If an error occurs |
| */ |
| public void write (char[] buf, int offset, int len) throws IOException |
| { |
| synchronized (lock) |
| { |
| if (buffer == null) |
| throw new IOException ("Stream closed"); |
| |
| // Bypass buffering if there is too much incoming data. |
| if (count + len > buffer.length) |
| { |
| localFlush (); |
| out.write(buf, offset, len); |
| } |
| else |
| { |
| System.arraycopy(buf, offset, buffer, count, len); |
| count += len; |
| if (count == buffer.length) |
| localFlush (); |
| } |
| } |
| } |
| |
| /** |
| * This method writes <code>len</code> chars from the <code>String</code> |
| * <code>str</code> starting at position <code>offset</code> in the string. |
| * These chars will be written to the internal buffer. However, if this |
| * write operation fills the buffer, the buffer will be flushed to the |
| * underlying output stream. |
| * |
| * @param str The <code>String</code> to write. |
| * @param offset The index into the string to start writing from. |
| * @param len The number of chars to write. |
| * |
| * @exception IOException If an error occurs |
| */ |
| public void write (String str, int offset, int len) throws IOException |
| { |
| synchronized (lock) |
| { |
| if (buffer == null) |
| throw new IOException ("Stream closed"); |
| |
| if (count + len > buffer.length) |
| { |
| localFlush (); |
| out.write(str, offset, len); |
| } |
| else |
| { |
| str.getChars(offset, offset + len, buffer, count); |
| count += len; |
| if (count == buffer.length) |
| localFlush (); |
| } |
| } |
| } |
| |
| // This should only be called with the lock held. |
| private void localFlush () throws IOException |
| { |
| if (count > 0) |
| { |
| out.write(buffer, 0, count); |
| count = 0; |
| } |
| } |
| } |