| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package java.io; |
| |
| /** |
| * The base class for all writers. A writer is a means of writing data to a |
| * target in a character-wise manner. Most output streams expect the |
| * {@link #flush()} method to be called before closing the stream, to ensure all |
| * data is actually written out. |
| * <p> |
| * This abstract class does not provide a fully working implementation, so it |
| * needs to be subclassed, and at least the {@link #write(char[], int, int)}, |
| * {@link #close()} and {@link #flush()} methods needs to be overridden. |
| * Overriding some of the non-abstract methods is also often advised, since it |
| * might result in higher efficiency. |
| * <p> |
| * Many specialized readers for purposes like reading from a file already exist |
| * in this package. |
| * |
| * @see Reader |
| */ |
| public abstract class Writer implements Appendable, Closeable, Flushable { |
| /** |
| * The object used to synchronize access to the writer. |
| */ |
| protected Object lock; |
| |
| /** |
| * Constructs a new {@code Writer} with {@code this} as the object used to |
| * synchronize critical sections. |
| */ |
| protected Writer() { |
| lock = this; |
| } |
| |
| /** |
| * Constructs a new {@code Writer} with {@code lock} used to synchronize |
| * critical sections. |
| * |
| * @param lock |
| * the {@code Object} used to synchronize critical sections. |
| * @throws NullPointerException |
| * if {@code lock} is {@code null}. |
| */ |
| protected Writer(Object lock) { |
| if (lock == null) { |
| throw new NullPointerException("lock == null"); |
| } |
| this.lock = lock; |
| } |
| |
| /** |
| * Closes this writer. Implementations of this method should free any |
| * resources associated with the writer. |
| * |
| * @throws IOException |
| * if an error occurs while closing this writer. |
| */ |
| public abstract void close() throws IOException; |
| |
| /** |
| * Flushes this writer. Implementations of this method should ensure that |
| * all buffered characters are written to the target. |
| * |
| * @throws IOException |
| * if an error occurs while flushing this writer. |
| */ |
| public abstract void flush() throws IOException; |
| |
| /** |
| * Writes the entire character buffer {@code buf} to the target. |
| * |
| * @param buf |
| * the non-null array containing characters to write. |
| * @throws IOException |
| * if this writer is closed or another I/O error occurs. |
| */ |
| public void write(char[] buf) throws IOException { |
| write(buf, 0, buf.length); |
| } |
| |
| /** |
| * Writes {@code count} characters starting at {@code offset} in {@code buf} |
| * to the target. |
| * |
| * @param buf |
| * the non-null character array to write. |
| * @param offset |
| * the index of the first character in {@code buf} to write. |
| * @param count |
| * the maximum number of characters to write. |
| * @throws IndexOutOfBoundsException |
| * if {@code offset < 0} or {@code count < 0}, or if {@code |
| * offset + count} is greater than the size of {@code buf}. |
| * @throws IOException |
| * if this writer is closed or another I/O error occurs. |
| */ |
| public abstract void write(char[] buf, int offset, int count) throws IOException; |
| |
| /** |
| * Writes one character to the target. Only the two least significant bytes |
| * of the integer {@code oneChar} are written. |
| * |
| * @param oneChar |
| * the character to write to the target. |
| * @throws IOException |
| * if this writer is closed or another I/O error occurs. |
| */ |
| public void write(int oneChar) throws IOException { |
| synchronized (lock) { |
| char[] oneCharArray = new char[1]; |
| oneCharArray[0] = (char) oneChar; |
| write(oneCharArray); |
| } |
| } |
| |
| /** |
| * Writes the characters from the specified string to the target. |
| * |
| * @param str |
| * the non-null string containing the characters to write. |
| * @throws IOException |
| * if this writer is closed or another I/O error occurs. |
| */ |
| public void write(String str) throws IOException { |
| write(str, 0, str.length()); |
| } |
| |
| /** |
| * Writes {@code count} characters from {@code str} starting at {@code |
| * offset} to the target. |
| * |
| * @param str |
| * the non-null string containing the characters to write. |
| * @param offset |
| * the index of the first character in {@code str} to write. |
| * @param count |
| * the number of characters from {@code str} to write. |
| * @throws IOException |
| * if this writer is closed or another I/O error occurs. |
| * @throws IndexOutOfBoundsException |
| * if {@code offset < 0} or {@code count < 0}, or if {@code |
| * offset + count} is greater than the length of {@code str}. |
| */ |
| public void write(String str, int offset, int count) throws IOException { |
| if ((offset | count) < 0 || offset > str.length() - count) { |
| throw new StringIndexOutOfBoundsException(str, offset, count); |
| } |
| char[] buf = new char[count]; |
| str.getChars(offset, offset + count, buf, 0); |
| synchronized (lock) { |
| write(buf, 0, buf.length); |
| } |
| } |
| |
| /** |
| * Appends the character {@code c} to the target. This method works the same |
| * way as {@link #write(int)}. |
| * |
| * @param c |
| * the character to append to the target stream. |
| * @return this writer. |
| * @throws IOException |
| * if this writer is closed or another I/O error occurs. |
| */ |
| public Writer append(char c) throws IOException { |
| write(c); |
| return this; |
| } |
| |
| /** |
| * Appends the character sequence {@code csq} to the target. This method |
| * works the same way as {@code Writer.write(csq.toString())}. If {@code |
| * csq} is {@code null}, then the string "null" is written to the target |
| * stream. |
| * |
| * @param csq |
| * the character sequence appended to the target. |
| * @return this writer. |
| * @throws IOException |
| * if this writer is closed or another I/O error occurs. |
| */ |
| public Writer append(CharSequence csq) throws IOException { |
| if (csq == null) { |
| csq = "null"; |
| } |
| write(csq.toString()); |
| return this; |
| } |
| |
| /** |
| * Appends a subsequence of the character sequence {@code csq} to the |
| * target. This method works the same way as {@code |
| * Writer.writer(csq.subsequence(start, end).toString())}. If {@code |
| * csq} is {@code null}, then the specified subsequence of the string "null" |
| * will be written to the target. |
| * |
| * @param csq |
| * the character sequence appended to the target. |
| * @param start |
| * the index of the first char in the character sequence appended |
| * to the target. |
| * @param end |
| * the index of the character following the last character of the |
| * subsequence appended to the target. |
| * @return this writer. |
| * @throws IOException |
| * if this writer is closed or another I/O error occurs. |
| * @throws IndexOutOfBoundsException |
| * if {@code start > end}, {@code start < 0}, {@code end < 0} or |
| * either {@code start} or {@code end} are greater or equal than |
| * the length of {@code csq}. |
| */ |
| public Writer append(CharSequence csq, int start, int end) throws IOException { |
| if (csq == null) { |
| csq = "null"; |
| } |
| write(csq.subSequence(start, end).toString()); |
| return this; |
| } |
| |
| /** |
| * Returns true if this writer has encountered and suppressed an error. Used |
| * by PrintWriters as an alternative to checked exceptions. |
| */ |
| boolean checkError() { |
| return false; |
| } |
| } |