Module java.base
Package java.nio.channels

Interface ScatteringByteChannel

All Superinterfaces:
AutoCloseable, Channel, Closeable, ReadableByteChannel
All Known Implementing Classes:
DatagramChannel, FileChannel, Pipe.SourceChannel, SocketChannel
public interface ScatteringByteChannel
extends ReadableByteChannel
A channel that can read bytes into a sequence of buffers.

A scattering read operation reads, in a single invocation, a sequence of bytes into one or more of a given sequence of buffers. Scattering reads are often useful when implementing network protocols or file formats that, for example, group data into segments consisting of one or more fixed-length headers followed by a variable-length body. Similar gathering write operations are defined in the GatheringByteChannel interface.

Since:
1.4

  • Method Summary

    Modifier and Type Method Description
    long read​(ByteBuffer[] dsts)
    Reads a sequence of bytes from this channel into the given buffers.
    long read​(ByteBuffer[] dsts, int offset, int length)
    Reads a sequence of bytes from this channel into a subsequence of the given buffers.

    Methods declared in interface java.nio.channels.Channel

    close, isOpen

    Methods declared in interface java.nio.channels.ReadableByteChannel

    read

  • Method Details

    • read

      long read​(ByteBuffer[] dsts, int offset, int length) throws IOException
      Reads a sequence of bytes from this channel into a subsequence of the given buffers.

      An invocation of this method attempts to read up to r bytes from this channel, where r is the total number of bytes remaining the specified subsequence of the given buffer array, that is, 

       dsts[offset].remaining()
     + dsts[offset+1].remaining()
     + ... + dsts[offset+length-1].remaining()
      at the moment that this method is invoked.

      Suppose that a byte sequence of length n is read, where 0 <= n <= r. Up to the first dsts[offset].remaining() bytes of this sequence are transferred into buffer dsts[offset], up to the next dsts[offset+1].remaining() bytes are transferred into buffer dsts[offset+1], and so forth, until the entire byte sequence is transferred into the given buffers. As many bytes as possible are transferred into each buffer, hence the final position of each updated buffer, except the last updated buffer, is guaranteed to be equal to that buffer's limit.

      This method may be invoked at any time. If another thread has already initiated a read operation upon this channel, however, then an invocation of this method will block until the first operation is complete.

      Parameters:
      dsts - The buffers into which bytes are to be transferred
      offset - The offset within the buffer array of the first buffer into which bytes are to be transferred; must be non-negative and no larger than dsts.length
      length - The maximum number of buffers to be accessed; must be non-negative and no larger than dsts.length - offset
      Returns:
      The number of bytes read, possibly zero, or -1 if the channel has reached end-of-stream
      Throws:
      IndexOutOfBoundsException - If the preconditions on the offset and length parameters do not hold
      IllegalArgumentException - If any of the buffers is read-only
      NonReadableChannelException - If this channel was not opened for reading
      ClosedChannelException - If this channel is closed
      AsynchronousCloseException - If another thread closes this channel while the read operation is in progress
      ClosedByInterruptException - If another thread interrupts the current thread while the read operation is in progress, thereby closing the channel and setting the current thread's interrupt status
      IOException - If some other I/O error occurs

    • read

      long read​(ByteBuffer[] dsts) throws IOException
      Reads a sequence of bytes from this channel into the given buffers.

      An invocation of this method of the form c.read(dsts) behaves in exactly the same manner as the invocation 

       c.read(dsts, 0, dsts.length);
      Parameters:
      dsts - The buffers into which bytes are to be transferred
      Returns:
      The number of bytes read, possibly zero, or -1 if the channel has reached end-of-stream
      Throws:
      IllegalArgumentException - If any of the buffers is read-only
      NonReadableChannelException - If this channel was not opened for reading
      ClosedChannelException - If this channel is closed
      AsynchronousCloseException - If another thread closes this channel while the read operation is in progress
      ClosedByInterruptException - If another thread interrupts the current thread while the read operation is in progress, thereby closing the channel and setting the current thread's interrupt status
      IOException - If some other I/O error occurs