Package java.util.zip

Class ZipFile.RAFStream

  • All Implemented Interfaces:
    Closeable, AutoCloseable
    Enclosing class:
    ZipFile
    public static class ZipFile.RAFStream
extends InputStream
    Wrap a stream around a RandomAccessFile. The RandomAccessFile is shared among all streams returned by getInputStream(), so we have to synchronize access to it. (We can optimize this by adding buffering here to reduce collisions.)

    We could support mark/reset, but we don't currently need them.

    • Method Detail

      • available

        public int available()
              throws IOException
        Description copied from class: InputStream
        Returns an estimated number of bytes that can be read or skipped without blocking for more input.

        Note that this method provides such a weak guarantee that it is not very useful in practice.

        Firstly, the guarantee is "without blocking for more input" rather than "without blocking": a read may still block waiting for I/O to complete — the guarantee is merely that it won't have to wait indefinitely for data to be written. The result of this method should not be used as a license to do I/O on a thread that shouldn't be blocked.

        Secondly, the result is a conservative estimate and may be significantly smaller than the actual number of bytes available. In particular, an implementation that always returns 0 would be correct. In general, callers should only use this method if they'd be satisfied with treating the result as a boolean yes or no answer to the question "is there definitely data ready?".

        Thirdly, the fact that a given number of bytes is "available" does not guarantee that a read or skip will actually read or skip that many bytes: they may read or skip fewer.

        It is particularly important to realize that you must not use this method to size a container and assume that you can read the entirety of the stream without needing to resize the container. Such callers should probably write everything they read to a ByteArrayOutputStream and convert that to a byte array. Alternatively, if you're reading from a file, File.length() returns the current length of the file (though assuming the file's length can't change may be incorrect, reading a file is inherently racy).

        The default implementation of this method in InputStream always returns 0. Subclasses should override this method if they are able to indicate the number of bytes available.

        Overrides:
        available in class InputStream
        Returns:
        the estimated number of bytes available
        Throws:
        IOException - if this stream is closed or an error occurs

      • read

        public int read()
         throws IOException
        Description copied from class: InputStream
        Reads a single byte from this stream and returns it as an integer in the range from 0 to 255. Returns -1 if the end of the stream has been reached. Blocks until one byte has been read, the end of the source stream is detected or an exception is thrown.
        Specified by:
        read in class InputStream
        Throws:
        IOException - if the stream is closed or another IOException occurs.

      • read

        public int read​(byte[] buffer,
                int byteOffset,
                int byteCount)
         throws IOException
        Description copied from class: InputStream
        Reads up to byteCount bytes from this stream and stores them in the byte array buffer starting at byteOffset. Returns the number of bytes actually read or -1 if the end of the stream has been reached.
        Overrides:
        read in class InputStream
        Throws:
        IOException - if the stream is closed or another IOException occurs.

      • skip

        public long skip​(long byteCount)
          throws IOException
        Description copied from class: InputStream
        Skips at most byteCount bytes in this stream. The number of actual bytes skipped may be anywhere between 0 and byteCount. If byteCount is negative, this method does nothing and returns 0, but some subclasses may throw.

        Note the "at most" in the description of this method: this method may choose to skip fewer bytes than requested. Callers should always check the return value.

        This default implementation reads bytes into a temporary buffer. Concrete subclasses should provide their own implementation.

        Overrides:
        skip in class InputStream
        Returns:
        the number of bytes actually skipped.
        Throws:
        IOException - if this stream is closed or another IOException occurs.