FilterWriter.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
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 */

package java.io;

/**
 * Abstract class for writing filtered character streams.
 * The abstract class <code>FilterWriter</code> itself
 * provides default methods that pass all requests to the
 * contained stream. Subclasses of <code>FilterWriter</code>
 * should override some of these methods and may also
 * provide additional methods and fields.
 *
 * @author Mark Reinhold
 * @since 1.1
 */
// 对输出流的简单包装，由子类实现具体的包装行为
public abstract class FilterWriter extends Writer {
    
    /**
     * The underlying character-output stream.
     */
    protected Writer out;   // 包装的输出流
    
    
    
    /*▼ 构造器 ████████████████████████████████████████████████████████████████████████████████┓ */
    
    /**
     * Create a new filtered writer.
     *
     * @param out a Writer object to provide the underlying stream.
     *
     * @throws NullPointerException if <code>out</code> is <code>null</code>
     */
    protected FilterWriter(Writer out) {
        super(out);
        this.out = out;
    }
    
    /*▲ 构造器 ████████████████████████████████████████████████████████████████████████████████┛ */
    
    
    
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    /**
     * Writes a single character.
     *
     * @throws IOException If an I/O error occurs
     */
    // 将指定的字符写入到输出流
    public void write(int c) throws IOException {
        out.write(c);
    }
    
    /**
     * Writes a portion of an array of characters.
     *
     * @param cbuf Buffer of characters to be written
     * @param off  Offset from which to start reading characters
     * @param len  Number of characters to be written
     *
     * @throws IndexOutOfBoundsException If the values of the {@code off} and {@code len} parameters
     *                                   cause the corresponding method of the underlying {@code Writer}
     *                                   to throw an {@code IndexOutOfBoundsException}
     * @throws IOException               If an I/O error occurs
     */
    // 将字符数组cbuf中off处起的len个字符写入到输出流
    public void write(char[] cbuf, int off, int len) throws IOException {
        out.write(cbuf, off, len);
    }
    
    /**
     * Writes a portion of a string.
     *
     * @param str String to be written
     * @param off Offset from which to start reading characters
     * @param len Number of characters to be written
     *
     * @throws IndexOutOfBoundsException If the values of the {@code off} and {@code len} parameters
     *                                   cause the corresponding method of the underlying {@code Writer}
     *                                   to throw an {@code IndexOutOfBoundsException}
     * @throws IOException               If an I/O error occurs
     */
    // 将字符串str中off处起的len个字符写入到输出流
    public void write(String str, int off, int len) throws IOException {
        out.write(str, off, len);
    }
    
    /*▲ 写 ████████████████████████████████████████████████████████████████████████████████┛ */
    
    
    
    /*▼ 杂项 ████████████████████████████████████████████████████████████████████████████████┓ */
    
    /**
     * Flushes the stream.
     *
     * @throws IOException If an I/O error occurs
     */
    // 将内部缓冲区中的字符写入到输出流
    public void flush() throws IOException {
        out.flush();
    }
    
    // 关闭输出流
    public void close() throws IOException {
        out.close();
    }
    
    /*▲ 杂项 ████████████████████████████████████████████████████████████████████████████████┛ */
    
}