jaroslav@1258: /*
jaroslav@1258:  * Copyright (c) 1996, 2011, Oracle and/or its affiliates. All rights reserved.
jaroslav@1258:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
jaroslav@1258:  *
jaroslav@1258:  * This code is free software; you can redistribute it and/or modify it
jaroslav@1258:  * under the terms of the GNU General Public License version 2 only, as
jaroslav@1258:  * published by the Free Software Foundation.  Oracle designates this
jaroslav@1258:  * particular file as subject to the "Classpath" exception as provided
jaroslav@1258:  * by Oracle in the LICENSE file that accompanied this code.
jaroslav@1258:  *
jaroslav@1258:  * This code is distributed in the hope that it will be useful, but WITHOUT
jaroslav@1258:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
jaroslav@1258:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
jaroslav@1258:  * version 2 for more details (a copy is included in the LICENSE file that
jaroslav@1258:  * accompanied this code).
jaroslav@1258:  *
jaroslav@1258:  * You should have received a copy of the GNU General Public License version
jaroslav@1258:  * 2 along with this work; if not, write to the Free Software Foundation,
jaroslav@1258:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
jaroslav@1258:  *
jaroslav@1258:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
jaroslav@1258:  * or visit www.oracle.com if you need additional information or have any
jaroslav@1258:  * questions.
jaroslav@1258:  */
jaroslav@1258: 
jaroslav@1258: package java.io;
jaroslav@1258: 
jaroslav@1258: 
jaroslav@1258: /**
jaroslav@1258:  * Writes text to a character-output stream, buffering characters so as to
jaroslav@1258:  * provide for the efficient writing of single characters, arrays, and strings.
jaroslav@1258:  *
jaroslav@1258:  * <p> The buffer size may be specified, or the default size may be accepted.
jaroslav@1258:  * The default is large enough for most purposes.
jaroslav@1258:  *
jaroslav@1258:  * <p> A newLine() method is provided, which uses the platform's own notion of
jaroslav@1258:  * line separator as defined by the system property <tt>line.separator</tt>.
jaroslav@1258:  * Not all platforms use the newline character ('\n') to terminate lines.
jaroslav@1258:  * Calling this method to terminate each output line is therefore preferred to
jaroslav@1258:  * writing a newline character directly.
jaroslav@1258:  *
jaroslav@1258:  * <p> In general, a Writer sends its output immediately to the underlying
jaroslav@1258:  * character or byte stream.  Unless prompt output is required, it is advisable
jaroslav@1258:  * to wrap a BufferedWriter around any Writer whose write() operations may be
jaroslav@1258:  * costly, such as FileWriters and OutputStreamWriters.  For example,
jaroslav@1258:  *
jaroslav@1258:  * <pre>
jaroslav@1258:  * PrintWriter out
jaroslav@1258:  *   = new PrintWriter(new BufferedWriter(new FileWriter("foo.out")));
jaroslav@1258:  * </pre>
jaroslav@1258:  *
jaroslav@1258:  * will buffer the PrintWriter's output to the file.  Without buffering, each
jaroslav@1258:  * invocation of a print() method would cause characters to be converted into
jaroslav@1258:  * bytes that would then be written immediately to the file, which can be very
jaroslav@1258:  * inefficient.
jaroslav@1258:  *
jaroslav@1258:  * @see PrintWriter
jaroslav@1258:  * @see FileWriter
jaroslav@1258:  * @see OutputStreamWriter
jaroslav@1258:  * @see java.nio.file.Files#newBufferedWriter
jaroslav@1258:  *
jaroslav@1258:  * @author      Mark Reinhold
jaroslav@1258:  * @since       JDK1.1
jaroslav@1258:  */
jaroslav@1258: 
jaroslav@1258: public class BufferedWriter extends Writer {
jaroslav@1258: 
jaroslav@1258:     private Writer out;
jaroslav@1258: 
jaroslav@1258:     private char cb[];
jaroslav@1258:     private int nChars, nextChar;
jaroslav@1258: 
jaroslav@1258:     private static int defaultCharBufferSize = 8192;
jaroslav@1258: 
jaroslav@1258:     /**
jaroslav@1258:      * Line separator string.  This is the value of the line.separator
jaroslav@1258:      * property at the moment that the stream was created.
jaroslav@1258:      */
jaroslav@1258:     private String lineSeparator;
jaroslav@1258: 
jaroslav@1258:     /**
jaroslav@1258:      * Creates a buffered character-output stream that uses a default-sized
jaroslav@1258:      * output buffer.
jaroslav@1258:      *
jaroslav@1258:      * @param  out  A Writer
jaroslav@1258:      */
jaroslav@1258:     public BufferedWriter(Writer out) {
jaroslav@1258:         this(out, defaultCharBufferSize);
jaroslav@1258:     }
jaroslav@1258: 
jaroslav@1258:     /**
jaroslav@1258:      * Creates a new buffered character-output stream that uses an output
jaroslav@1258:      * buffer of the given size.
jaroslav@1258:      *
jaroslav@1258:      * @param  out  A Writer
jaroslav@1258:      * @param  sz   Output-buffer size, a positive integer
jaroslav@1258:      *
jaroslav@1258:      * @exception  IllegalArgumentException  If sz is <= 0
jaroslav@1258:      */
jaroslav@1258:     public BufferedWriter(Writer out, int sz) {
jaroslav@1258:         super(out);
jaroslav@1258:         if (sz <= 0)
jaroslav@1258:             throw new IllegalArgumentException("Buffer size <= 0");
jaroslav@1258:         this.out = out;
jaroslav@1258:         cb = new char[sz];
jaroslav@1258:         nChars = sz;
jaroslav@1258:         nextChar = 0;
jaroslav@1258: 
jaroslav@1258:         lineSeparator = java.security.AccessController.doPrivileged(
jaroslav@1258:             new sun.security.action.GetPropertyAction("line.separator"));
jaroslav@1258:     }
jaroslav@1258: 
jaroslav@1258:     /** Checks to make sure that the stream has not been closed */
jaroslav@1258:     private void ensureOpen() throws IOException {
jaroslav@1258:         if (out == null)
jaroslav@1258:             throw new IOException("Stream closed");
jaroslav@1258:     }
jaroslav@1258: 
jaroslav@1258:     /**
jaroslav@1258:      * Flushes the output buffer to the underlying character stream, without
jaroslav@1258:      * flushing the stream itself.  This method is non-private only so that it
jaroslav@1258:      * may be invoked by PrintStream.
jaroslav@1258:      */
jaroslav@1258:     void flushBuffer() throws IOException {
jaroslav@1258:         synchronized (lock) {
jaroslav@1258:             ensureOpen();
jaroslav@1258:             if (nextChar == 0)
jaroslav@1258:                 return;
jaroslav@1258:             out.write(cb, 0, nextChar);
jaroslav@1258:             nextChar = 0;
jaroslav@1258:         }
jaroslav@1258:     }
jaroslav@1258: 
jaroslav@1258:     /**
jaroslav@1258:      * Writes a single character.
jaroslav@1258:      *
jaroslav@1258:      * @exception  IOException  If an I/O error occurs
jaroslav@1258:      */
jaroslav@1258:     public void write(int c) throws IOException {
jaroslav@1258:         synchronized (lock) {
jaroslav@1258:             ensureOpen();
jaroslav@1258:             if (nextChar >= nChars)
jaroslav@1258:                 flushBuffer();
jaroslav@1258:             cb[nextChar++] = (char) c;
jaroslav@1258:         }
jaroslav@1258:     }
jaroslav@1258: 
jaroslav@1258:     /**
jaroslav@1258:      * Our own little min method, to avoid loading java.lang.Math if we've run
jaroslav@1258:      * out of file descriptors and we're trying to print a stack trace.
jaroslav@1258:      */
jaroslav@1258:     private int min(int a, int b) {
jaroslav@1258:         if (a < b) return a;
jaroslav@1258:         return b;
jaroslav@1258:     }
jaroslav@1258: 
jaroslav@1258:     /**
jaroslav@1258:      * Writes a portion of an array of characters.
jaroslav@1258:      *
jaroslav@1258:      * <p> Ordinarily this method stores characters from the given array into
jaroslav@1258:      * this stream's buffer, flushing the buffer to the underlying stream as
jaroslav@1258:      * needed.  If the requested length is at least as large as the buffer,
jaroslav@1258:      * however, then this method will flush the buffer and write the characters
jaroslav@1258:      * directly to the underlying stream.  Thus redundant
jaroslav@1258:      * <code>BufferedWriter</code>s will not copy data unnecessarily.
jaroslav@1258:      *
jaroslav@1258:      * @param  cbuf  A character array
jaroslav@1258:      * @param  off   Offset from which to start reading characters
jaroslav@1258:      * @param  len   Number of characters to write
jaroslav@1258:      *
jaroslav@1258:      * @exception  IOException  If an I/O error occurs
jaroslav@1258:      */
jaroslav@1258:     public void write(char cbuf[], int off, int len) throws IOException {
jaroslav@1258:         synchronized (lock) {
jaroslav@1258:             ensureOpen();
jaroslav@1258:             if ((off < 0) || (off > cbuf.length) || (len < 0) ||
jaroslav@1258:                 ((off + len) > cbuf.length) || ((off + len) < 0)) {
jaroslav@1258:                 throw new IndexOutOfBoundsException();
jaroslav@1258:             } else if (len == 0) {
jaroslav@1258:                 return;
jaroslav@1258:             }
jaroslav@1258: 
jaroslav@1258:             if (len >= nChars) {
jaroslav@1258:                 /* If the request length exceeds the size of the output buffer,
jaroslav@1258:                    flush the buffer and then write the data directly.  In this
jaroslav@1258:                    way buffered streams will cascade harmlessly. */
jaroslav@1258:                 flushBuffer();
jaroslav@1258:                 out.write(cbuf, off, len);
jaroslav@1258:                 return;
jaroslav@1258:             }
jaroslav@1258: 
jaroslav@1258:             int b = off, t = off + len;
jaroslav@1258:             while (b < t) {
jaroslav@1258:                 int d = min(nChars - nextChar, t - b);
jaroslav@1258:                 System.arraycopy(cbuf, b, cb, nextChar, d);
jaroslav@1258:                 b += d;
jaroslav@1258:                 nextChar += d;
jaroslav@1258:                 if (nextChar >= nChars)
jaroslav@1258:                     flushBuffer();
jaroslav@1258:             }
jaroslav@1258:         }
jaroslav@1258:     }
jaroslav@1258: 
jaroslav@1258:     /**
jaroslav@1258:      * Writes a portion of a String.
jaroslav@1258:      *
jaroslav@1258:      * <p> If the value of the <tt>len</tt> parameter is negative then no
jaroslav@1258:      * characters are written.  This is contrary to the specification of this
jaroslav@1258:      * method in the {@linkplain java.io.Writer#write(java.lang.String,int,int)
jaroslav@1258:      * superclass}, which requires that an {@link IndexOutOfBoundsException} be
jaroslav@1258:      * thrown.
jaroslav@1258:      *
jaroslav@1258:      * @param  s     String to be written
jaroslav@1258:      * @param  off   Offset from which to start reading characters
jaroslav@1258:      * @param  len   Number of characters to be written
jaroslav@1258:      *
jaroslav@1258:      * @exception  IOException  If an I/O error occurs
jaroslav@1258:      */
jaroslav@1258:     public void write(String s, int off, int len) throws IOException {
jaroslav@1258:         synchronized (lock) {
jaroslav@1258:             ensureOpen();
jaroslav@1258: 
jaroslav@1258:             int b = off, t = off + len;
jaroslav@1258:             while (b < t) {
jaroslav@1258:                 int d = min(nChars - nextChar, t - b);
jaroslav@1258:                 s.getChars(b, b + d, cb, nextChar);
jaroslav@1258:                 b += d;
jaroslav@1258:                 nextChar += d;
jaroslav@1258:                 if (nextChar >= nChars)
jaroslav@1258:                     flushBuffer();
jaroslav@1258:             }
jaroslav@1258:         }
jaroslav@1258:     }
jaroslav@1258: 
jaroslav@1258:     /**
jaroslav@1258:      * Writes a line separator.  The line separator string is defined by the
jaroslav@1258:      * system property <tt>line.separator</tt>, and is not necessarily a single
jaroslav@1258:      * newline ('\n') character.
jaroslav@1258:      *
jaroslav@1258:      * @exception  IOException  If an I/O error occurs
jaroslav@1258:      */
jaroslav@1258:     public void newLine() throws IOException {
jaroslav@1258:         write(lineSeparator);
jaroslav@1258:     }
jaroslav@1258: 
jaroslav@1258:     /**
jaroslav@1258:      * Flushes the stream.
jaroslav@1258:      *
jaroslav@1258:      * @exception  IOException  If an I/O error occurs
jaroslav@1258:      */
jaroslav@1258:     public void flush() throws IOException {
jaroslav@1258:         synchronized (lock) {
jaroslav@1258:             flushBuffer();
jaroslav@1258:             out.flush();
jaroslav@1258:         }
jaroslav@1258:     }
jaroslav@1258: 
jaroslav@1258:     public void close() throws IOException {
jaroslav@1258:         synchronized (lock) {
jaroslav@1258:             if (out == null) {
jaroslav@1258:                 return;
jaroslav@1258:             }
jaroslav@1258:             try {
jaroslav@1258:                 flushBuffer();
jaroslav@1258:             } finally {
jaroslav@1258:                 out.close();
jaroslav@1258:                 out = null;
jaroslav@1258:                 cb = null;
jaroslav@1258:             }
jaroslav@1258:         }
jaroslav@1258:     }
jaroslav@1258: }