Java™ Platform
Standard Ed. 6

java.nio.channels
Interface GatheringByteChannel

All Superinterfaces:
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
 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 inherited from interface java.nio.channels.WritableByteChannel
write
 
Methods inherited from interface java.nio.channels.Channel
close, isOpen
 

Method Detail

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

Java™ Platform
Standard Ed. 6

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For further API reference and developer documentation, see Java SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

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