On 2018-07-20, Jason Harrop wrote: > Given a ZipFile, its easy to read the size of ZipArchiveEntry
> How to do this when using ZipArchiveInputStream? > The documentation says: ZipFile has access to the central directory and can > extract entries using the data descriptor reliably. The same is true for > ZipArchiveInputStream as long as the entry is DEFLATED. TBH the paragraph doesn't make much sense to me but has very likely been written by my former self. > Assuming the entry is DEFLATED, I'm not sure how to read that? ZipFile uses random access and can read size and crc information from anywhere inside of the archive. ZipArchiveInputStream reads a stream byte by byte and can only provide you with information it has read by the time you ask for it. The structure of a ZIP archive has meta data in the so called local file header followed by the actual content of each entry. Sometimes this local file header contains the entry's size and you can ask ZipArchiveEntry for its size before reading the entry. Under certain circumstances - and using DEFLATE is one of them - the size can be stored after the entry data inside the so called data descriptor. If the archive uses the data descriptor ZipArchiveEntry's getSize can only return "unknown" until you have read all data of the entry. Once you have read the entry's content completely, ZipArchiveEntry will know the size. This is what the "Note" in https://commons.apache.org/proper/commons-compress/javadocs/api-release/org/apache/commons/compress/archivers/zip/ZipArchiveEntry.html#getSize-- says. Stefan --------------------------------------------------------------------- To unsubscribe, e-mail: user-unsubscr...@commons.apache.org For additional commands, e-mail: user-h...@commons.apache.org
