Streaming GZIPOutputStream

StreamingGZIPOutputStream.java

/*
 * Copyright © 2011 Mike Duigou. No rights reserved.
 */
import java.io.IOException;
import java.io.OutputStream;
import java.util.zip.Deflater;
import java.util.zip.GZIPOutputStream;

/**
 * Extends GZIPOutputStream to improve behaviour of created streams for incrementally streamed content. This
 * allows shorter reads on the receiving end to get the next uncompressed chunk and, for cases where the
 * stream might fail unexpectedly, a greater chance of being able to read up to the end of the stream. The
 * resulting stream may be slightly less efficiently compressed (higher overhead) than the default
 * implementation, especially if the {@link #flush()} method is called frequently.
 *
 * @implSpec Flush compressed data to the output stream for each deflate operation.
 */
public class StreamingGZIPOutputStream extends GZIPOutputStream {
    
    public StreamingGZIPOutputStream(OutputStream out) throws IOException {
        this(out, 512);
    }

    public StreamingGZIPOutputStream(OutputStream out, int size) throws IOException {
        super(out, size, true);
    }

    @Override
    protected void deflate() throws IOException {
        // This forces eager flush for each deflate operation
        int len = def.deflate(buf, 0, buf.length, Deflater.SYNC_FLUSH);
        if (len > 0) {
            out.write(buf, 0, len);
        }
    }
}