Top Description Methods
java.nio.channels

public Interface ScatteringByteChannel

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

Authors
Mark Reinhold, JSR-51 Expert Group
Since
1.4

Method Summary

Modifier and TypeMethod and Description
public long

Returns:

The number of bytes read, possibly zero, or -1 if the channel has reached end-of-stream
read(ByteBuffer[]
The buffers into which bytes are to be transferred
dsts, int
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
offset, int
The maximum number of buffers to be accessed; must be non-negative and no larger than dsts.length - offset
length)

Reads a sequence of bytes from this channel into a subsequence of the given buffers.

public long

Returns:

The number of bytes read, possibly zero, or -1 if the channel has reached end-of-stream
read(ByteBuffer[]
The buffers into which bytes are to be transferred
dsts)

Reads a sequence of bytes from this channel into the given buffers.

Inherited from java.nio.channels.ReadableByteChannel:
read

Method Detail

readback to summary
public 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 in the specified subsequence of the given buffer array, that is,

dsts[offset].remaining() + dsts[offset+1].remaining() + ... + dsts[offset+length-1].remaining() 
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:ByteBuffer[]

The buffers into which bytes are to be transferred

offset:int

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:int

The maximum number of buffers to be accessed; must be non-negative and no larger than dsts.length - offset

Returns:long

The number of bytes read, possibly zero, or -1 if the channel has reached end-of-stream

Exceptions
IOException:
If some other I/O error occurs
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
readback to summary
public 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); 
c.read(dsts, 0, dsts.length);
Parameters
dsts:ByteBuffer[]

The buffers into which bytes are to be transferred

Returns:long

The number of bytes read, possibly zero, or -1 if the channel has reached end-of-stream

Exceptions
IOException:
If some other I/O error occurs
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