Class Segment


  • public class Segment
    extends java.lang.Object
    A Pack200 archive consists of one or more segments. Each segment is stand-alone, in the sense that every segment has the magic number header; thus, every segment is also a valid archive. However, it is possible to combine (non-GZipped) archives into a single large archive by concatenation alone. Thus all the hard work in unpacking an archive falls to understanding a segment. The first component of a segment is the header; this contains (amongst other things) the expected counts of constant pool entries, which in turn defines how many values need to be read from the stream. Because values are variable width (see Codec), it is not possible to calculate the start of the next segment, although one of the header values does hint at the size of the segment if non-zero, which can be used for buffering purposes. Note that this does not perform any buffering of the input stream; each value will be read on a byte-by-byte basis. It does not perform GZip decompression automatically; both of these are expected to be done by the caller if the stream has the magic header for GZip streams (GZIPInputStream.GZIP_MAGIC). In any case, if GZip decompression is being performed the input stream will be buffered at a higher level, and thus this can read on a byte-oriented basis.
    • Constructor Detail

    • Method Detail

      • unpack

        public void unpack​(java.io.InputStream in,
                           java.util.jar.JarOutputStream out)
                    throws java.io.IOException,
                           Pack200Exception
        Unpacks a packed stream (either .pack. or .pack.gz) into a corresponding JarOuputStream.
        Parameters:
        in - a packed stream.
        out - output stream.
        Throws:
        Pack200Exception - if there is a problem unpacking
        java.io.IOException - if there is a problem with I/O during unpacking
      • writeJar

        public void writeJar​(java.util.jar.JarOutputStream out)
                      throws java.io.IOException,
                             Pack200Exception
        Writes the segment to an output stream. The output stream should be pre-buffered for efficiency. Also takes the same input stream for reading, since the file bits may not be loaded and thus just copied from one stream to another. Doesn't close the output stream when finished, in case there are more entries (e.g. further segments) to be written.
        Parameters:
        out - the JarOutputStream to write data to
        Throws:
        java.io.IOException - if an error occurs while reading or writing to the streams
        Pack200Exception - if an error occurs while processing data
      • setPreRead

        public void setPreRead​(boolean value)
      • setLogLevel

        public void setLogLevel​(int logLevel)
      • setLogStream

        public void setLogStream​(java.io.OutputStream logStream)
      • log

        public void log​(int logLevel,
                        java.lang.String message)
      • overrideDeflateHint

        public void overrideDeflateHint​(boolean deflateHint)
        Override the archive's deflate hint with the given boolean
        Parameters:
        deflateHint - - the deflate hint to use