001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.io.output;
018
019import java.io.FilterWriter;
020import java.io.IOException;
021import java.io.Writer;
022
023/**
024 * Writer which breaks larger output blocks into chunks.
025 * Native code may need to copy the input array; if the write buffer
026 * is very large this can cause OOME.
027 *
028 * @since 2.5
029 */
030public class ChunkedWriter extends FilterWriter {
031
032    /**
033     * The default chunk size to use, i.e. {@value} bytes.
034     */
035    private static final int DEFAULT_CHUNK_SIZE = 1024 * 4;
036
037    /**
038     * The maximum chunk size to us when writing data arrays
039     */
040    private final int chunkSize;
041
042    /**
043     * Creates a new writer that uses the specified chunk size.
044     *
045     * @param writer the writer to wrap
046     * @param chunkSize the chunk size to use; must be a positive number.
047     * @throws IllegalArgumentException if the chunk size is <= 0
048     */
049    public ChunkedWriter(final Writer writer, final int chunkSize) {
050       super(writer);
051       if (chunkSize <= 0) {
052           throw new IllegalArgumentException();
053       }
054       this.chunkSize = chunkSize;
055    }
056
057    /**
058     * Creates a new writer that uses a chunk size of {@link #DEFAULT_CHUNK_SIZE}
059     * @param writer the writer to wrap
060     */
061    public ChunkedWriter(final Writer writer) {
062        this(writer, DEFAULT_CHUNK_SIZE);
063    }
064
065    /**
066     * writes the data buffer in chunks to the underlying writer
067     * @param data The data
068     * @param srcOffset the offset
069     * @param length the number of bytes to write
070     *
071     * @throws IOException upon error
072     */
073    @Override
074    public void write(final char[] data, final int srcOffset, final int length) throws IOException {
075        int bytes = length;
076        int dstOffset = srcOffset;
077        while(bytes > 0) {
078            final int chunk = Math.min(bytes, chunkSize);
079            out.write(data, dstOffset, chunk);
080            bytes -= chunk;
081            dstOffset += chunk;
082        }
083    }
084
085}