ojluni/src/main/java/java/io/BufferedWriter.java - platform/libcore.git - Git at Google

 /*
  * Copyright (c) 1996, 2011, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this
  * particular file as subject to the "Classpath" exception as provided
  * by Oracle in the LICENSE file that accompanied this code.
  *
  * This code 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
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */

 package java.io;


 /**
  * Writes text to a character-output stream, buffering characters so as to
  * provide for the efficient writing of single characters, arrays, and strings.
  *
  * <p> The buffer size may be specified, or the default size may be accepted.
  * The default is large enough for most purposes.
  *
  * <p> A newLine() method is provided, which uses the platform's own notion of
  * line separator as defined by the system property <tt>line.separator</tt>.
  * Not all platforms use the newline character ('\n') to terminate lines.
  * Calling this method to terminate each output line is therefore preferred to
  * writing a newline character directly.
  *
  * <p> In general, a Writer sends its output immediately to the underlying
  * character or byte stream.  Unless prompt output is required, it is advisable
  * to wrap a BufferedWriter around any Writer whose write() operations may be
  * costly, such as FileWriters and OutputStreamWriters.  For example,
  *
  * <pre>
  * PrintWriter out
  *   = new PrintWriter(new BufferedWriter(new FileWriter("foo.out")));
  * </pre>
  *
  * will buffer the PrintWriter's output to the file.  Without buffering, each
  * invocation of a print() method would cause characters to be converted into
  * bytes that would then be written immediately to the file, which can be very
  * inefficient.
  *
  * @see PrintWriter
  * @see FileWriter
  * @see OutputStreamWriter
  * @see java.nio.file.Files#newBufferedWriter
  *
  * @author      Mark Reinhold
  * @since       JDK1.1
  */

 public class BufferedWriter extends Writer {

     private Writer out;

     private char cb[];
     private int nChars, nextChar;

     private static int defaultCharBufferSize = 8192;

     /**
      * Line separator string.  This is the value of the line.separator
      * property at the moment that the stream was created.
      */
     private String lineSeparator;

     /**
      * Creates a buffered character-output stream that uses a default-sized
      * output buffer.
      *
      * @param  out  A Writer
      */
     public BufferedWriter(Writer out) {
         this(out, defaultCharBufferSize);
     }

     /**
      * Creates a new buffered character-output stream that uses an output
      * buffer of the given size.
      *
      * @param  out  A Writer
      * @param  sz   Output-buffer size, a positive integer
      *
      * @exception  IllegalArgumentException  If sz is <= 0
      */
     public BufferedWriter(Writer out, int sz) {
         super(out);
         if (sz <= 0)
             throw new IllegalArgumentException("Buffer size <= 0");
         this.out = out;
         cb = new char[sz];
         nChars = sz;
         nextChar = 0;

         lineSeparator = java.security.AccessController.doPrivileged(
             new sun.security.action.GetPropertyAction("line.separator"));
     }

     /** Checks to make sure that the stream has not been closed */
     private void ensureOpen() throws IOException {
         if (out == null)
             throw new IOException("Stream closed");
     }

     /**
      * Flushes the output buffer to the underlying character stream, without
      * flushing the stream itself.  This method is non-private only so that it
      * may be invoked by PrintStream.
      */
     void flushBuffer() throws IOException {
         synchronized (lock) {
             ensureOpen();
             if (nextChar == 0)
                 return;
             out.write(cb, 0, nextChar);
             nextChar = 0;
         }
     }

     /**
      * Writes a single character.
      *
      * @exception  IOException  If an I/O error occurs
      */
     public void write(int c) throws IOException {
         synchronized (lock) {
             ensureOpen();
             if (nextChar >= nChars)
                 flushBuffer();
             cb[nextChar++] = (char) c;
         }
     }

     /**
      * Our own little min method, to avoid loading java.lang.Math if we've run
      * out of file descriptors and we're trying to print a stack trace.
      */
     private int min(int a, int b) {
         if (a < b) return a;
         return b;
     }

     /**
      * Writes a portion of an array of characters.
      *
      * <p> Ordinarily this method stores characters from the given array into
      * this stream's buffer, flushing the buffer to the underlying stream as
      * needed.  If the requested length is at least as large as the buffer,
      * however, then this method will flush the buffer and write the characters
      * directly to the underlying stream.  Thus redundant
      * <code>BufferedWriter</code>s will not copy data unnecessarily.
      *
      * @param  cbuf  A character array
      * @param  off   Offset from which to start reading characters
      * @param  len   Number of characters to write
      *
      * @exception  IOException  If an I/O error occurs
      */
     public void write(char cbuf[], int off, int len) throws IOException {
         synchronized (lock) {
             ensureOpen();
             if ((off < 0) || (off > cbuf.length) || (len < 0) ||
                 ((off + len) > cbuf.length) || ((off + len) < 0)) {
                 throw new IndexOutOfBoundsException();
             } else if (len == 0) {
                 return;
             }

             if (len >= nChars) {
                 /* If the request length exceeds the size of the output buffer,
                    flush the buffer and then write the data directly.  In this
                    way buffered streams will cascade harmlessly. */
                 flushBuffer();
                 out.write(cbuf, off, len);
                 return;
             }

             int b = off, t = off + len;
             while (b < t) {
                 int d = min(nChars - nextChar, t - b);
                 System.arraycopy(cbuf, b, cb, nextChar, d);
                 b += d;
                 nextChar += d;
                 if (nextChar >= nChars)
                     flushBuffer();
             }
         }
     }

     /**
      * Writes a portion of a String.
      *
      * <p> If the value of the <tt>len</tt> parameter is negative then no
      * characters are written.  This is contrary to the specification of this
      * method in the {@linkplain java.io.Writer#write(java.lang.String,int,int)
      * superclass}, which requires that an {@link IndexOutOfBoundsException} be
      * thrown.
      *
      * @param  s     String to be written
      * @param  off   Offset from which to start reading characters
      * @param  len   Number of characters to be written
      *
      * @exception  IOException  If an I/O error occurs
      */
     public void write(String s, int off, int len) throws IOException {
         synchronized (lock) {
             ensureOpen();

             int b = off, t = off + len;
             while (b < t) {
                 int d = min(nChars - nextChar, t - b);
                 s.getChars(b, b + d, cb, nextChar);
                 b += d;
                 nextChar += d;
                 if (nextChar >= nChars)
                     flushBuffer();
             }
         }
     }

     /**
      * Writes a line separator.  The line separator string is defined by the
      * system property <tt>line.separator</tt>, and is not necessarily a single
      * newline ('\n') character.
      *
      * @exception  IOException  If an I/O error occurs
      */
     public void newLine() throws IOException {
         write(lineSeparator);
     }

     /**
      * Flushes the stream.
      *
      * @exception  IOException  If an I/O error occurs
      */
     public void flush() throws IOException {
         synchronized (lock) {
             flushBuffer();
             out.flush();
         }
     }

     public void close() throws IOException {
         synchronized (lock) {
             if (out == null) {
                 return;
             }
             try {
                 flushBuffer();
             } finally {
                 out.close();
                 out = null;
                 cb = null;
             }
         }
     }
 }
	/*
	* Copyright (c) 1996, 2011, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code 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
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package java.io;


	/**
	* Writes text to a character-output stream, buffering characters so as to
	* provide for the efficient writing of single characters, arrays, and strings.
	*
	* <p> The buffer size may be specified, or the default size may be accepted.
	* The default is large enough for most purposes.
	*
	* <p> A newLine() method is provided, which uses the platform's own notion of
	* line separator as defined by the system property <tt>line.separator</tt>.
	* Not all platforms use the newline character ('\n') to terminate lines.
	* Calling this method to terminate each output line is therefore preferred to
	* writing a newline character directly.
	*
	* <p> In general, a Writer sends its output immediately to the underlying
	* character or byte stream. Unless prompt output is required, it is advisable
	* to wrap a BufferedWriter around any Writer whose write() operations may be
	* costly, such as FileWriters and OutputStreamWriters. For example,
	*
	* <pre>
	* PrintWriter out
	* = new PrintWriter(new BufferedWriter(new FileWriter("foo.out")));
	* </pre>
	*
	* will buffer the PrintWriter's output to the file. Without buffering, each
	* invocation of a print() method would cause characters to be converted into
	* bytes that would then be written immediately to the file, which can be very
	* inefficient.
	*
	* @see PrintWriter
	* @see FileWriter
	* @see OutputStreamWriter
	* @see java.nio.file.Files#newBufferedWriter
	*
	* @author Mark Reinhold
	* @since JDK1.1
	*/

	public class BufferedWriter extends Writer {

	private Writer out;

	private char cb[];
	private int nChars, nextChar;

	private static int defaultCharBufferSize = 8192;

	/**
	* Line separator string. This is the value of the line.separator
	* property at the moment that the stream was created.
	*/
	private String lineSeparator;

	/**
	* Creates a buffered character-output stream that uses a default-sized
	* output buffer.
	*
	* @param out A Writer
	*/
	public BufferedWriter(Writer out) {
	this(out, defaultCharBufferSize);
	}

	/**
	* Creates a new buffered character-output stream that uses an output
	* buffer of the given size.
	*
	* @param out A Writer
	* @param sz Output-buffer size, a positive integer
	*
	* @exception IllegalArgumentException If sz is <= 0
	*/
	public BufferedWriter(Writer out, int sz) {
	super(out);
	if (sz <= 0)
	throw new IllegalArgumentException("Buffer size <= 0");
	this.out = out;
	cb = new char[sz];
	nChars = sz;
	nextChar = 0;

	lineSeparator = java.security.AccessController.doPrivileged(
	new sun.security.action.GetPropertyAction("line.separator"));
	}

	/** Checks to make sure that the stream has not been closed */
	private void ensureOpen() throws IOException {
	if (out == null)
	throw new IOException("Stream closed");
	}

	/**
	* Flushes the output buffer to the underlying character stream, without
	* flushing the stream itself. This method is non-private only so that it
	* may be invoked by PrintStream.
	*/
	void flushBuffer() throws IOException {
	synchronized (lock) {
	ensureOpen();
	if (nextChar == 0)
	return;
	out.write(cb, 0, nextChar);
	nextChar = 0;
	}
	}

	/**
	* Writes a single character.
	*
	* @exception IOException If an I/O error occurs
	*/
	public void write(int c) throws IOException {
	synchronized (lock) {
	ensureOpen();
	if (nextChar >= nChars)
	flushBuffer();
	cb[nextChar++] = (char) c;
	}
	}

	/**
	* Our own little min method, to avoid loading java.lang.Math if we've run
	* out of file descriptors and we're trying to print a stack trace.
	*/
	private int min(int a, int b) {
	if (a < b) return a;
	return b;
	}

	/**
	* Writes a portion of an array of characters.
	*
	* <p> Ordinarily this method stores characters from the given array into
	* this stream's buffer, flushing the buffer to the underlying stream as
	* needed. If the requested length is at least as large as the buffer,
	* however, then this method will flush the buffer and write the characters
	* directly to the underlying stream. Thus redundant
	* <code>BufferedWriter</code>s will not copy data unnecessarily.
	*
	* @param cbuf A character array
	* @param off Offset from which to start reading characters
	* @param len Number of characters to write
	*
	* @exception IOException If an I/O error occurs
	*/
	public void write(char cbuf[], int off, int len) throws IOException {
	synchronized (lock) {
	ensureOpen();
	if ((off < 0) \|\| (off > cbuf.length) \|\| (len < 0) \|\|
	((off + len) > cbuf.length) \|\| ((off + len) < 0)) {
	throw new IndexOutOfBoundsException();
	} else if (len == 0) {
	return;
	}

	if (len >= nChars) {
	/* If the request length exceeds the size of the output buffer,
	flush the buffer and then write the data directly. In this
	way buffered streams will cascade harmlessly. */
	flushBuffer();
	out.write(cbuf, off, len);
	return;
	}

	int b = off, t = off + len;
	while (b < t) {
	int d = min(nChars - nextChar, t - b);
	System.arraycopy(cbuf, b, cb, nextChar, d);
	b += d;
	nextChar += d;
	if (nextChar >= nChars)
	flushBuffer();
	}
	}
	}

	/**
	* Writes a portion of a String.
	*
	* <p> If the value of the <tt>len</tt> parameter is negative then no
	* characters are written. This is contrary to the specification of this
	* method in the {@linkplain java.io.Writer#write(java.lang.String,int,int)
	* superclass}, which requires that an {@link IndexOutOfBoundsException} be
	* thrown.
	*
	* @param s String to be written
	* @param off Offset from which to start reading characters
	* @param len Number of characters to be written
	*
	* @exception IOException If an I/O error occurs
	*/
	public void write(String s, int off, int len) throws IOException {
	synchronized (lock) {
	ensureOpen();

	int b = off, t = off + len;
	while (b < t) {
	int d = min(nChars - nextChar, t - b);
	s.getChars(b, b + d, cb, nextChar);
	b += d;
	nextChar += d;
	if (nextChar >= nChars)
	flushBuffer();
	}
	}
	}

	/**
	* Writes a line separator. The line separator string is defined by the
	* system property <tt>line.separator</tt>, and is not necessarily a single
	* newline ('\n') character.
	*
	* @exception IOException If an I/O error occurs
	*/
	public void newLine() throws IOException {
	write(lineSeparator);
	}

	/**
	* Flushes the stream.
	*
	* @exception IOException If an I/O error occurs
	*/
	public void flush() throws IOException {
	synchronized (lock) {
	flushBuffer();
	out.flush();
	}
	}

	public void close() throws IOException {
	synchronized (lock) {
	if (out == null) {
	return;
	}
	try {
	flushBuffer();
	} finally {
	out.close();
	out = null;
	cb = null;
	}
	}
	}
	}