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GatheringByteChannel

public interface GatheringByteChannel
implements WritableByteChannel

java.nio.channels.GatheringByteChannel
Known Indirect Subclasses


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.

Summary

Public methods

abstract long write(ByteBuffer[] srcs)

Writes a sequence of bytes to this channel from the given buffers.

abstract long write(ByteBuffer[] srcs, int offset, int length)

Writes a sequence of bytes to this channel from a subsequence of the given buffers.

Inherited methods

From interface java.nio.channels.WritableByteChannel
From interface java.nio.channels.Channel
From interface java.io.Closeable
From interface java.lang.AutoCloseable

Public methods

write

Added in API level 1
long write (ByteBuffer[] srcs)

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 ByteBuffer: The buffers from which bytes are to be retrieved
Returns
long 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

write

Added in API level 1
long write (ByteBuffer[] srcs, 
                int offset, 
                int length)

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 ByteBuffer: The buffers from which bytes are to be retrieved
offset int: 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 int: The maximum number of buffers to be accessed; must be non-negative and no larger than srcs.length - offset
Returns
long 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
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