Top Description Methods
java.nio.channels

public Interface GatheringByteChannel

extends WritableByteChannel
Known Direct Implementers
java.nio.channels.Pipe.SinkChannel, java.nio.channels.SocketChannel, java.nio.channels.DatagramChannel, java.nio.channels.FileChannel
Imports
java.io.IOException, java.nio.ByteBuffer
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.

Authors
Mark Reinhold, JSR-51 Expert Group
Since
1.4

Method Summary

Modifier and TypeMethod and Description
public long

Returns:

The number of bytes written, possibly zero
write(ByteBuffer[]
The buffers from which bytes are to be retrieved
srcs, 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
offset, int
The maximum number of buffers to be accessed; must be non-negative and no larger than srcs.length - offset
length)

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

public long

Returns:

The number of bytes written, possibly zero
write(ByteBuffer[]
The buffers from which bytes are to be retrieved
srcs)

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

Inherited from java.nio.channels.WritableByteChannel:
write

Method Detail

writeback to summary
public 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() 
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

Exceptions
IOException:
If some other I/O error occurs
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
writeback to summary
public 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); 
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

Exceptions
IOException:
If some other I/O error occurs
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