Bug ID 4813885 xử lý sự cố này. Nhận xét về "DamonHD", được gửi vào ngày 9 tháng 9 năm 2006 (khoảng nửa chừng báo cáo lỗi) chứa ví dụ về FlushableGZIPOutputStream mà ông đã xây dựng trên đầu trang của Jazzlib'snet.sf.jazzlib.DeflaterOutputStream.
Để tham khảo, đây là một (định dạng lại) chiết xuất:
/**
* Substitute for GZIPOutputStream that maximises compression and has a usable
* flush(). This is also more careful about its output writes for efficiency,
* and indeed buffers them to minimise the number of write()s downstream which
* is especially useful where each write() has a cost such as an OS call, a disc
* write, or a network packet.
*/
public class FlushableGZIPOutputStream extends net.sf.jazzlib.DeflaterOutputStream {
private final CRC32 crc = new CRC32();
private final static int GZIP_MAGIC = 0x8b1f;
private final OutputStream os;
/** Set when input has arrived and not yet been compressed and flushed downstream. */
private boolean somethingWritten;
public FlushableGZIPOutputStream(final OutputStream os) throws IOException {
this(os, 8192);
}
public FlushableGZIPOutputStream(final OutputStream os, final int bufsize) throws IOException {
super(new FilterOutputStream(new BufferedOutputStream(os, bufsize)) {
/** Suppress inappropriate/inefficient flush()es by DeflaterOutputStream. */
@Override
public void flush() {
}
}, new net.sf.jazzlib.Deflater(net.sf.jazzlib.Deflater.BEST_COMPRESSION, true));
this.os = os;
writeHeader();
crc.reset();
}
public synchronized void write(byte[] buf, int off, int len) throws IOException {
somethingWritten = true;
super.write(buf, off, len);
crc.update(buf, off, len);
}
/**
* Flush any accumulated input downstream in compressed form. We overcome
* some bugs/misfeatures here so that:
* <ul>
* <li>We won't allow the GZIP header to be flushed on its own without real compressed
* data in the same write downstream.
* <li>We ensure that any accumulated uncompressed data really is forced through the
* compressor.
* <li>We prevent spurious empty compressed blocks being produced from successive
* flush()es with no intervening new data.
* </ul>
*/
@Override
public synchronized void flush() throws IOException {
if (!somethingWritten) { return; }
// We call this to get def.flush() called,
// but suppress the (usually premature) out.flush() called internally.
super.flush();
// Since super.flush() seems to fail to reliably force output,
// possibly due to over-cautious def.needsInput() guard following def.flush(),
// we try to force the issue here by bypassing the guard.
int len;
while((len = def.deflate(buf, 0, buf.length)) > 0) {
out.write(buf, 0, len);
}
// Really flush the stream below us...
os.flush();
// Further flush()es ignored until more input data data written.
somethingWritten = false;
}
public synchronized void close() throws IOException {
if (!def.finished()) {
def.finish();
do {
int len = def.deflate(buf, 0, buf.length);
if (len <= 0) {
break;
}
out.write(buf, 0, len);
} while (!def.finished());
}
// Write trailer
out.write(generateTrailer());
out.close();
}
// ...
}
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Tôi đang làm việc với Java6. – Hemeroc