| /* |
| * 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; |
| |
| |
| /** |
| * Abstract class for writing to character streams. The only methods that a |
| * subclass must implement are write(char[], int, int), flush(), and close(). |
| * Most subclasses, however, will override some of the methods defined here in |
| * order to provide higher efficiency, additional functionality, or both. |
| * |
| * @see Writer |
| * @see BufferedWriter |
| * @see CharArrayWriter |
| * @see FilterWriter |
| * @see OutputStreamWriter |
| * @see FileWriter |
| * @see PipedWriter |
| * @see PrintWriter |
| * @see StringWriter |
| * @see Reader |
| * |
| * @author Mark Reinhold |
| * @since JDK1.1 |
| */ |
| |
| public abstract class Writer implements Appendable, Closeable, Flushable { |
| |
| /** |
| * Temporary buffer used to hold writes of strings and single characters |
| */ |
| private char[] writeBuffer; |
| |
| /** |
| * Size of writeBuffer, must be >= 1 |
| */ |
| private static final int WRITE_BUFFER_SIZE = 1024; |
| |
| /** |
| * The object used to synchronize operations on this stream. For |
| * efficiency, a character-stream object may use an object other than |
| * itself to protect critical sections. A subclass should therefore use |
| * the object in this field rather than <tt>this</tt> or a synchronized |
| * method. |
| */ |
| protected Object lock; |
| |
| /** |
| * Creates a new character-stream writer whose critical sections will |
| * synchronize on the writer itself. |
| */ |
| protected Writer() { |
| this.lock = this; |
| } |
| |
| /** |
| * Creates a new character-stream writer whose critical sections will |
| * synchronize on the given object. |
| * |
| * @param lock |
| * Object to synchronize on |
| */ |
| protected Writer(Object lock) { |
| if (lock == null) { |
| throw new NullPointerException(); |
| } |
| this.lock = lock; |
| } |
| |
| /** |
| * Writes a single character. The character to be written is contained in |
| * the 16 low-order bits of the given integer value; the 16 high-order bits |
| * are ignored. |
| * |
| * <p> Subclasses that intend to support efficient single-character output |
| * should override this method. |
| * |
| * @param c |
| * int specifying a character to be written |
| * |
| * @throws IOException |
| * If an I/O error occurs |
| */ |
| public void write(int c) throws IOException { |
| synchronized (lock) { |
| if (writeBuffer == null){ |
| writeBuffer = new char[WRITE_BUFFER_SIZE]; |
| } |
| writeBuffer[0] = (char) c; |
| write(writeBuffer, 0, 1); |
| } |
| } |
| |
| /** |
| * Writes an array of characters. |
| * |
| * @param cbuf |
| * Array of characters to be written |
| * |
| * @throws IOException |
| * If an I/O error occurs |
| */ |
| public void write(char cbuf[]) throws IOException { |
| write(cbuf, 0, cbuf.length); |
| } |
| |
| /** |
| * Writes a portion of an array of characters. |
| * |
| * @param cbuf |
| * Array of characters |
| * |
| * @param off |
| * Offset from which to start writing characters |
| * |
| * @param len |
| * Number of characters to write |
| * |
| * @throws IOException |
| * If an I/O error occurs |
| */ |
| abstract public void write(char cbuf[], int off, int len) throws IOException; |
| |
| /** |
| * Writes a string. |
| * |
| * @param str |
| * String to be written |
| * |
| * @throws IOException |
| * If an I/O error occurs |
| */ |
| public void write(String str) throws IOException { |
| write(str, 0, str.length()); |
| } |
| |
| /** |
| * Writes a portion of a string. |
| * |
| * @param str |
| * A String |
| * |
| * @param off |
| * Offset from which to start writing characters |
| * |
| * @param len |
| * Number of characters to write |
| * |
| * @throws IndexOutOfBoundsException |
| * If <tt>off</tt> is negative, or <tt>len</tt> is negative, |
| * or <tt>off+len</tt> is negative or greater than the length |
| * of the given string |
| * |
| * @throws IOException |
| * If an I/O error occurs |
| */ |
| public void write(String str, int off, int len) throws IOException { |
| synchronized (lock) { |
| char cbuf[]; |
| if (len <= WRITE_BUFFER_SIZE) { |
| if (writeBuffer == null) { |
| writeBuffer = new char[WRITE_BUFFER_SIZE]; |
| } |
| cbuf = writeBuffer; |
| } else { // Don't permanently allocate very large buffers. |
| cbuf = new char[len]; |
| } |
| str.getChars(off, (off + len), cbuf, 0); |
| write(cbuf, 0, len); |
| } |
| } |
| |
| /** |
| * Appends the specified character sequence to this writer. |
| * |
| * <p> An invocation of this method of the form <tt>out.append(csq)</tt> |
| * behaves in exactly the same way as the invocation |
| * |
| * <pre> |
| * out.write(csq.toString()) </pre> |
| * |
| * <p> Depending on the specification of <tt>toString</tt> for the |
| * character sequence <tt>csq</tt>, the entire sequence may not be |
| * appended. For instance, invoking the <tt>toString</tt> method of a |
| * character buffer will return a subsequence whose content depends upon |
| * the buffer's position and limit. |
| * |
| * @param csq |
| * The character sequence to append. If <tt>csq</tt> is |
| * <tt>null</tt>, then the four characters <tt>"null"</tt> are |
| * appended to this writer. |
| * |
| * @return This writer |
| * |
| * @throws IOException |
| * If an I/O error occurs |
| * |
| * @since 1.5 |
| */ |
| public Writer append(CharSequence csq) throws IOException { |
| if (csq == null) |
| write("null"); |
| else |
| write(csq.toString()); |
| return this; |
| } |
| |
| /** |
| * Appends a subsequence of the specified character sequence to this writer. |
| * <tt>Appendable</tt>. |
| * |
| * <p> An invocation of this method of the form <tt>out.append(csq, start, |
| * end)</tt> when <tt>csq</tt> is not <tt>null</tt> behaves in exactly the |
| * same way as the invocation |
| * |
| * <pre> |
| * out.write(csq.subSequence(start, end).toString()) </pre> |
| * |
| * @param csq |
| * The character sequence from which a subsequence will be |
| * appended. If <tt>csq</tt> is <tt>null</tt>, then characters |
| * will be appended as if <tt>csq</tt> contained the four |
| * characters <tt>"null"</tt>. |
| * |
| * @param start |
| * The index of the first character in the subsequence |
| * |
| * @param end |
| * The index of the character following the last character in the |
| * subsequence |
| * |
| * @return This writer |
| * |
| * @throws IndexOutOfBoundsException |
| * If <tt>start</tt> or <tt>end</tt> are negative, <tt>start</tt> |
| * is greater than <tt>end</tt>, or <tt>end</tt> is greater than |
| * <tt>csq.length()</tt> |
| * |
| * @throws IOException |
| * If an I/O error occurs |
| * |
| * @since 1.5 |
| */ |
| public Writer append(CharSequence csq, int start, int end) throws IOException { |
| CharSequence cs = (csq == null ? "null" : csq); |
| write(cs.subSequence(start, end).toString()); |
| return this; |
| } |
| |
| /** |
| * Appends the specified character to this writer. |
| * |
| * <p> An invocation of this method of the form <tt>out.append(c)</tt> |
| * behaves in exactly the same way as the invocation |
| * |
| * <pre> |
| * out.write(c) </pre> |
| * |
| * @param c |
| * The 16-bit character to append |
| * |
| * @return This writer |
| * |
| * @throws IOException |
| * If an I/O error occurs |
| * |
| * @since 1.5 |
| */ |
| public Writer append(char c) throws IOException { |
| write(c); |
| return this; |
| } |
| |
| /** |
| * Flushes the stream. If the stream has saved any characters from the |
| * various write() methods in a buffer, write them immediately to their |
| * intended destination. Then, if that destination is another character or |
| * byte stream, flush it. Thus one flush() invocation will flush all the |
| * buffers in a chain of Writers and OutputStreams. |
| * |
| * <p> If the intended destination of this stream is an abstraction provided |
| * by the underlying operating system, for example a file, then flushing the |
| * stream guarantees only that bytes previously written to the stream are |
| * passed to the operating system for writing; it does not guarantee that |
| * they are actually written to a physical device such as a disk drive. |
| * |
| * @throws IOException |
| * If an I/O error occurs |
| */ |
| abstract public void flush() throws IOException; |
| |
| /** |
| * Closes the stream, flushing it first. Once the stream has been closed, |
| * further write() or flush() invocations will cause an IOException to be |
| * thrown. Closing a previously closed stream has no effect. |
| * |
| * @throws IOException |
| * If an I/O error occurs |
| */ |
| abstract public void close() throws IOException; |
| |
| } |
