276 lines
9.1 KiB
Java
276 lines
9.1 KiB
Java
|
/*
|
||
|
|
* Copyright (c) 1996, 2016, 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 {@code line.separator}.
|
||
|
|
* 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 1.1
|
||
|
|
*/
|
||
|
|
|
||
|
|
public class BufferedWriter extends Writer {
|
||
|
|
|
||
|
|
private Writer out;
|
||
|
|
|
||
|
|
private char cb[];
|
||
|
|
private int nChars, nextChar;
|
||
|
|
|
||
|
|
private static int defaultCharBufferSize = 8192;
|
||
|
|
|
||
|
|
/**
|
||
|
|
* 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 {@code sz <= 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;
|
||
|
|
}
|
||
|
|
|
||
|
|
/** 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}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
|
||
|
|
*
|
||
|
|
* @throws IndexOutOfBoundsException
|
||
|
|
* If {@code off} is negative, or {@code len} is negative,
|
||
|
|
* or {@code off + len} is negative or greater than the length
|
||
|
|
* of the given array
|
||
|
|
*
|
||
|
|
* @throws 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.
|
||
|
|
*
|
||
|
|
* @implSpec
|
||
|
|
* While the specification of this method in the
|
||
|
|
* {@linkplain java.io.Writer#write(java.lang.String,int,int) superclass}
|
||
|
|
* recommends that an {@link IndexOutOfBoundsException} be thrown
|
||
|
|
* if {@code len} is negative or {@code off + len} is negative,
|
||
|
|
* the implementation in this class does not throw such an exception in
|
||
|
|
* these cases but instead simply writes no characters.
|
||
|
|
*
|
||
|
|
* @param s String to be written
|
||
|
|
* @param off Offset from which to start reading characters
|
||
|
|
* @param len Number of characters to be written
|
||
|
|
*
|
||
|
|
* @throws IndexOutOfBoundsException
|
||
|
|
* If {@code off} is negative,
|
||
|
|
* or {@code off + len} is greater than the length
|
||
|
|
* of the given string
|
||
|
|
*
|
||
|
|
* @throws 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 {@code line.separator}, and is not necessarily a single
|
||
|
|
* newline ('\n') character.
|
||
|
|
*
|
||
|
|
* @exception IOException If an I/O error occurs
|
||
|
|
*/
|
||
|
|
public void newLine() throws IOException {
|
||
|
|
write(System.lineSeparator());
|
||
|
|
}
|
||
|
|
|
||
|
|
/**
|
||
|
|
* Flushes the stream.
|
||
|
|
*
|
||
|
|
* @exception IOException If an I/O error occurs
|
||
|
|
*/
|
||
|
|
public void flush() throws IOException {
|
||
|
|
synchronized (lock) {
|
||
|
|
flushBuffer();
|
||
|
|
out.flush();
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
@SuppressWarnings("try")
|
||
|
|
public void close() throws IOException {
|
||
|
|
synchronized (lock) {
|
||
|
|
if (out == null) {
|
||
|
|
return;
|
||
|
|
}
|
||
|
|
try (Writer w = out) {
|
||
|
|
flushBuffer();
|
||
|
|
} finally {
|
||
|
|
out = null;
|
||
|
|
cb = null;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|
||
|
|
}
|