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 *      https://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 */
017
018package org.apache.commons.io.output;
019
020import java.io.FilterWriter;
021import java.io.IOException;
022import java.io.Writer;
023
024import org.apache.commons.io.IOUtils;
025
026/**
027 * Writer which breaks larger output blocks into chunks. Native code may need to copy the input array; if the write buffer is very large this can cause OOME.
028 *
029 * @since 2.5
030 */
031public class ChunkedWriter extends FilterWriter {
032
033    /**
034     * The default chunk size to use: {@value} bytes.
035     */
036    private static final int DEFAULT_CHUNK_SIZE = IOUtils.DEFAULT_BUFFER_SIZE;
037
038    /**
039     * The maximum chunk size to us when writing data arrays.
040     */
041    private final int chunkSize;
042
043    /**
044     * Constructs a new writer that uses a chunk size of {@link #DEFAULT_CHUNK_SIZE}
045     *
046     * @param writer the writer to wrap.
047     */
048    public ChunkedWriter(final Writer writer) {
049        this(writer, DEFAULT_CHUNK_SIZE);
050    }
051
052    /**
053     * Constructs a new writer that uses the specified chunk size.
054     *
055     * @param writer    the writer to wrap.
056     * @param chunkSize the chunk size to use; must be a positive number.
057     * @throws IllegalArgumentException if the chunk size is <= 0.
058     */
059    public ChunkedWriter(final Writer writer, final int chunkSize) {
060        super(writer);
061        if (chunkSize <= 0) {
062            throw new IllegalArgumentException();
063        }
064        this.chunkSize = chunkSize;
065    }
066
067    /**
068     * Writes the data buffer in chunks to the underlying writer.
069     *
070     * @param data      The data.
071     * @param srcOffset the offset.
072     * @param length    the number of bytes to write.
073     * @throws NullPointerException if the data is {@code null}.
074     * @throws IndexOutOfBoundsException if {@code srcOffset} or {@code length} are negative,
075     *                                   or if {@code srcOffset + length} is greater than {@code data.length}.
076     * @throws IOException If an I/O error occurs.
077     */
078    @Override
079    public void write(final char[] data, final int srcOffset, final int length) throws IOException {
080        IOUtils.checkFromIndexSize(data, srcOffset, length);
081        int bytes = length;
082        int dstOffset = srcOffset;
083        while (bytes > 0) {
084            final int chunk = Math.min(bytes, chunkSize);
085            out.write(data, dstOffset, chunk);
086            bytes -= chunk;
087            dstOffset += chunk;
088        }
089    }
090}