001 /*
002 * Copyright 1994-2003 Sun Microsystems, Inc. All Rights Reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation. Sun designates this
008 * particular file as subject to the "Classpath" exception as provided
009 * by Sun in the LICENSE file that accompanied this code.
010 *
011 * This code is distributed in the hope that it will be useful, but WITHOUT
012 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014 * version 2 for more details (a copy is included in the LICENSE file that
015 * accompanied this code).
016 *
017 * You should have received a copy of the GNU General Public License version
018 * 2 along with this work; if not, write to the Free Software Foundation,
019 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020 *
021 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022 * CA 95054 USA or visit www.sun.com if you need additional information or
023 * have any questions.
024 */
025
026 package java.io;
027
028 /**
029 * The class implements a buffered output stream. By setting up such
030 * an output stream, an application can write bytes to the underlying
031 * output stream without necessarily causing a call to the underlying
032 * system for each byte written.
033 *
034 * @author Arthur van Hoff
035 * @version 1.40, 05/05/07
036 * @since JDK1.0
037 */
038 public class BufferedOutputStream extends FilterOutputStream {
039 /**
040 * The internal buffer where data is stored.
041 */
042 protected byte buf[];
043
044 /**
045 * The number of valid bytes in the buffer. This value is always
046 * in the range <tt>0</tt> through <tt>buf.length</tt>; elements
047 * <tt>buf[0]</tt> through <tt>buf[count-1]</tt> contain valid
048 * byte data.
049 */
050 protected int count;
051
052 /**
053 * Creates a new buffered output stream to write data to the
054 * specified underlying output stream.
055 *
056 * @param out the underlying output stream.
057 */
058 public BufferedOutputStream(OutputStream out) {
059 this (out, 8192);
060 }
061
062 /**
063 * Creates a new buffered output stream to write data to the
064 * specified underlying output stream with the specified buffer
065 * size.
066 *
067 * @param out the underlying output stream.
068 * @param size the buffer size.
069 * @exception IllegalArgumentException if size <= 0.
070 */
071 public BufferedOutputStream(OutputStream out, int size) {
072 super (out);
073 if (size <= 0) {
074 throw new IllegalArgumentException("Buffer size <= 0");
075 }
076 buf = new byte[size];
077 }
078
079 /** Flush the internal buffer */
080 private void flushBuffer() throws IOException {
081 if (count > 0) {
082 out.write(buf, 0, count);
083 count = 0;
084 }
085 }
086
087 /**
088 * Writes the specified byte to this buffered output stream.
089 *
090 * @param b the byte to be written.
091 * @exception IOException if an I/O error occurs.
092 */
093 public synchronized void write(int b) throws IOException {
094 if (count >= buf.length) {
095 flushBuffer();
096 }
097 buf[count++] = (byte) b;
098 }
099
100 /**
101 * Writes <code>len</code> bytes from the specified byte array
102 * starting at offset <code>off</code> to this buffered output stream.
103 *
104 * <p> Ordinarily this method stores bytes from the given array into this
105 * stream's buffer, flushing the buffer to the underlying output stream as
106 * needed. If the requested length is at least as large as this stream's
107 * buffer, however, then this method will flush the buffer and write the
108 * bytes directly to the underlying output stream. Thus redundant
109 * <code>BufferedOutputStream</code>s will not copy data unnecessarily.
110 *
111 * @param b the data.
112 * @param off the start offset in the data.
113 * @param len the number of bytes to write.
114 * @exception IOException if an I/O error occurs.
115 */
116 public synchronized void write(byte b[], int off, int len)
117 throws IOException {
118 if (len >= buf.length) {
119 /* If the request length exceeds the size of the output buffer,
120 flush the output buffer and then write the data directly.
121 In this way buffered streams will cascade harmlessly. */
122 flushBuffer();
123 out.write(b, off, len);
124 return;
125 }
126 if (len > buf.length - count) {
127 flushBuffer();
128 }
129 System.arraycopy(b, off, buf, count, len);
130 count += len;
131 }
132
133 /**
134 * Flushes this buffered output stream. This forces any buffered
135 * output bytes to be written out to the underlying output stream.
136 *
137 * @exception IOException if an I/O error occurs.
138 * @see java.io.FilterOutputStream#out
139 */
140 public synchronized void flush() throws IOException {
141 flushBuffer();
142 out.flush();
143 }
144 }
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