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
023import org.apache.commons.io.IOUtils;
024
025/**
026 * Writer which breaks larger output blocks into chunks.
027 * Native code may need to copy the input array; if the write buffer
028 * is very large this can cause OOME.
029 *
030 * @since 2.5
031 */
032public class ChunkedWriter extends FilterWriter {
033
034    /**
035     * The default chunk size to use: {@value} bytes.
036     */
037    private static final int DEFAULT_CHUNK_SIZE = IOUtils.DEFAULT_BUFFER_SIZE;
038
039    /**
040     * The maximum chunk size to us when writing data arrays
041     */
042    private final int chunkSize;
043
044    /**
045     * Constructs a new writer that uses a chunk size of {@link #DEFAULT_CHUNK_SIZE}
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     *
074     * @throws IOException upon error
075     */
076    @Override
077    public void write(final char[] data, final int srcOffset, final int length) throws IOException {
078        int bytes = length;
079        int dstOffset = srcOffset;
080        while (bytes > 0) {
081            final int chunk = Math.min(bytes, chunkSize);
082            out.write(data, dstOffset, chunk);
083            bytes -= chunk;
084            dstOffset += chunk;
085        }
086    }
087
088}