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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