Module java.base
Package java.nio.channels

Interface GatheringByteChannel

All Superinterfaces:
AutoCloseable, Channel, Closeable, WritableByteChannel
All Known Implementing Classes:
DatagramChannel, FileChannel, Pipe.SinkChannel, SocketChannel
public interface GatheringByteChannel extends WritableByteChannel
A channel that can write bytes from a sequence of buffers.

A gathering write operation writes, in a single invocation, a sequence of bytes from one or more of a given sequence of buffers. Gathering writes 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 scattering read operations are defined in the ScatteringByteChannel interface.

Since:
1.4

  • Method Summary

    Modifier and Type
    Method
    Description
    long
    write​(ByteBuffer[] srcs)
    Writes a sequence of bytes to this channel from the given buffers.
    long
    write​(ByteBuffer[] srcs, int offset, int length)
    Writes a sequence of bytes to this channel from a subsequence of the given buffers.

    Methods declared in interface java.nio.channels.Channel

    close, isOpen

    Methods declared in interface java.nio.channels.WritableByteChannel

    write

  • Method Details

    • write

      long write​(ByteBuffer[] srcs, int offset, int length) throws IOException
      Writes a sequence of bytes to this channel from a subsequence of the given buffers.

      An attempt is made to write up to r bytes to this channel, where r is the total number of bytes remaining in the specified subsequence of the given buffer array, that is, 

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

      Suppose that a byte sequence of length n is written, where 0 <= n <= r. Up to the first srcs[offset].remaining() bytes of this sequence are written from buffer srcs[offset], up to the next srcs[offset+1].remaining() bytes are written from buffer srcs[offset+1], and so forth, until the entire byte sequence is written. As many bytes as possible are written from 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.

      Unless otherwise specified, a write operation will return only after writing all of the r requested bytes. Some types of channels, depending upon their state, may write only some of the bytes or possibly none at all. A socket channel in non-blocking mode, for example, cannot write any more bytes than are free in the socket's output buffer.

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

      Parameters:
      srcs - The buffers from which bytes are to be retrieved
      offset - The offset within the buffer array of the first buffer from which bytes are to be retrieved; must be non-negative and no larger than srcs.length
      length - The maximum number of buffers to be accessed; must be non-negative and no larger than srcs.length - offset
      Returns:
      The number of bytes written, possibly zero
      Throws:
      IndexOutOfBoundsException - If the preconditions on the offset and length parameters do not hold
      NonWritableChannelException - If this channel was not opened for writing
      ClosedChannelException - If this channel is closed
      AsynchronousCloseException - If another thread closes this channel while the write operation is in progress
      ClosedByInterruptException - If another thread interrupts the current thread while the write operation is in progress, thereby closing the channel and setting the current thread's interrupt status
      IOException - If some other I/O error occurs

    • write

      long write​(ByteBuffer[] srcs) throws IOException
      Writes a sequence of bytes to this channel from the given buffers.

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

       c.write(srcs, 0, srcs.length);
      Parameters:
      srcs - The buffers from which bytes are to be retrieved
      Returns:
      The number of bytes written, possibly zero
      Throws:
      NonWritableChannelException - If this channel was not opened for writing
      ClosedChannelException - If this channel is closed
      AsynchronousCloseException - If another thread closes this channel while the write operation is in progress
      ClosedByInterruptException - If another thread interrupts the current thread while the write operation is in progress, thereby closing the channel and setting the current thread's interrupt status
      IOException - If some other I/O error occurs