001/*
002 *  Copyright 2013 Chris Pheby
003 *
004 *  Licensed under the Apache License, Version 2.0 (the "License");
005 *  you may not use this file except in compliance with the License.
006 *  You may obtain a copy of the License at
007 *
008 *      http://www.apache.org/licenses/LICENSE-2.0
009 *
010 *  Unless required by applicable law or agreed to in writing, software
011 *  distributed under the License is distributed on an "AS IS" BASIS,
012 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 *  See the License for the specific language governing permissions and
014 *  limitations under the License.
015 */
016package org.jadira.lang.io.buffered;
017
018import java.io.FilterOutputStream;
019import java.io.IOException;
020import java.io.OutputStream;
021
022/**
023 * Provides the basic structure for implementing BufferedOutputStreams. Subclasses typically differ in terms of how they provide the buffer.
024 * Some of the functionality needs to be effectively reproduced from BufferedOutputStream - such methods reference the equivalents in that class.
025 */
026public abstract class AbstractBufferedOutputStream extends FilterOutputStream {
027
028    /** The default buffer size in bytes */
029    public static int DEFAULT_BUFFER_SIZE = 8192;
030
031    private int count;
032
033    /**
034     * A BufferedOutputStream where the buffer is provided by a byte array. Use this class as an alternative to {@link java.io.BufferedOutputStream}
035     * @param out OutputStream to be decorated
036     */
037    public AbstractBufferedOutputStream(OutputStream out) {
038        this(out, DEFAULT_BUFFER_SIZE);
039    }
040
041    /**
042     * Creates a new instance with the given buffer size in bytes.
043     * @param out OutputStream to be decorated
044     * @param size The size of the buffer in bytes
045     * @see java.io.BufferedOutputStream#BufferedOutputStream(OutputStream, int)
046     */
047    public AbstractBufferedOutputStream(OutputStream out, int size) {
048        super(out);
049
050        if (size <= 0) {
051            throw new IllegalArgumentException("Buffer size may not be less than or equal to zero");
052        }
053    }
054
055    private void flushBuffer() throws IOException {
056
057        if (count > 0) {
058            out.write(bytes(), 0, count);
059            count = 0;
060        }
061    }
062
063    /**
064     * @see java.io.BufferedOutputStream#write(int)
065     */
066    public void write(int b) throws IOException {
067
068        if (count >= limit()) {
069            flushBuffer();
070        }
071
072        put((byte) b);
073    }
074
075    /**
076     * @see java.io.BufferedOutputStream#write(byte[], int, int)
077     */
078    public void write(byte b[], int off, int len) throws IOException {
079
080        if (len >= limit()) {
081            flushBuffer();
082            out.write(b, off, len);
083            return;
084        }
085
086        if (len > limit() - count) {
087            flushBuffer();
088        }
089
090        put(count, b, off, len);
091        count += len;
092    }
093
094    /**
095     * @see java.io.BufferedOutputStream#flush
096     */
097    public void flush() throws IOException {
098
099        flushBuffer();
100        out.flush();
101    }
102
103    @Override
104    public void close() throws IOException {
105        try {
106            super.close();
107        } finally {
108            clean();
109        }
110    }
111
112    /**
113     * Return the bytes in the buffer as a byte array
114     * @return The bytes
115     */
116    protected abstract byte[] bytes();
117
118    /**
119     * Put a single byte into the buffer
120     * @param b The byte
121     */
122    protected abstract void put(byte b);
123
124    /**
125     * Puts bytes into the buffer
126     * @param count The number of bytes already written into the buffer
127     * @param b The byte array with the bytes to put
128     * @param off Offset to write from in the bytes, b
129     * @param len The number of bytes to write
130     */
131    protected abstract void put(int count, byte[] b, int off, int len);
132
133    /**
134     * Returns the limit of the buffer
135     * @return The limit
136     */
137    protected abstract int limit();
138
139    /**
140     * Performs any necessary cleaning of the buffer and releasing of resources.
141     */
142    protected abstract void clean();
143}