Module java.base

Package java.nio.channels

Class Channels

java.lang.Object

java.nio.channels.Channels

public final class Channels
extends Object

Utility methods for channels and streams.

This class defines static methods that support the interoperation of the stream classes of the java.io package with the channel classes of this package.

Since:

1.4

Method Summary

Modifier and Type	Method	Description
static ReadableByteChannel	newChannel(InputStream in)	Constructs a channel that reads bytes from the given stream.
static WritableByteChannel	newChannel(OutputStream out)	Constructs a channel that writes bytes to the given stream.
static InputStream	newInputStream(AsynchronousByteChannel ch)	Constructs a stream that reads bytes from the given channel.
static InputStream	newInputStream(ReadableByteChannel ch)	Constructs a stream that reads bytes from the given channel.
static OutputStream	newOutputStream(AsynchronousByteChannel ch)	Constructs a stream that writes bytes to the given channel.
static OutputStream	newOutputStream(WritableByteChannel ch)	Constructs a stream that writes bytes to the given channel.
static Reader	newReader(ReadableByteChannel ch, String csName)	Constructs a reader that decodes bytes from the given channel according to the named charset.
static Reader	newReader(ReadableByteChannel ch, Charset charset)	Constructs a reader that decodes bytes from the given channel according to the given charset.
static Reader	newReader(ReadableByteChannel ch, CharsetDecoder dec, int minBufferCap)	Constructs a reader that decodes bytes from the given channel using the given decoder.
static Writer	newWriter(WritableByteChannel ch, String csName)	Constructs a writer that encodes characters according to the named charset and writes the resulting bytes to the given channel.
static Writer	newWriter(WritableByteChannel ch, Charset charset)	Constructs a writer that encodes characters according to the given charset and writes the resulting bytes to the given channel.
static Writer	newWriter(WritableByteChannel ch, CharsetEncoder enc, int minBufferCap)	Constructs a writer that encodes characters using the given encoder and writes the resulting bytes to the given channel.

Methods declared in class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

newInputStream

public static InputStream newInputStream(ReadableByteChannel ch)

Constructs a stream that reads bytes from the given channel.

The read and transferTo methods of the resulting stream will throw an IllegalBlockingModeException if invoked while the underlying channel is in non-blocking mode. The transferTo method will also throw an IllegalBlockingModeException if invoked to transfer bytes to an output stream that writes to an underlying channel in non-blocking mode. The stream will not be buffered, and it will not support the mark or reset methods. The stream will be safe for access by multiple concurrent threads. Closing the stream will in turn cause the channel to be closed.

Parameters:

ch - The channel from which bytes will be read

Returns:

A new input stream

newOutputStream

public static OutputStream newOutputStream(WritableByteChannel ch)

Constructs a stream that writes bytes to the given channel.

The write methods of the resulting stream will throw an IllegalBlockingModeException if invoked while the underlying channel is in non-blocking mode. The stream will not be buffered. The stream will be safe for access by multiple concurrent threads. Closing the stream will in turn cause the channel to be closed.

Parameters:

ch - The channel to which bytes will be written

Returns:

A new output stream

newInputStream

public static InputStream newInputStream(AsynchronousByteChannel ch)

Constructs a stream that reads bytes from the given channel.

The stream will not be buffered, and it will not support the mark or reset methods. The stream will be safe for access by multiple concurrent threads. Closing the stream will in turn cause the channel to be closed.

Parameters:

ch - The channel from which bytes will be read

Returns:

A new input stream

Since:

1.7

newOutputStream

public static OutputStream newOutputStream(AsynchronousByteChannel ch)

Constructs a stream that writes bytes to the given channel.

The stream will not be buffered. The stream will be safe for access by multiple concurrent threads. Closing the stream will in turn cause the channel to be closed.

Parameters:

ch - The channel to which bytes will be written

Returns:

A new output stream

Since:

1.7

newChannel

public static ReadableByteChannel newChannel(InputStream in)

Constructs a channel that reads bytes from the given stream.

The resulting channel will not be buffered; it will simply redirect its I/O operations to the given stream. Reading from the resulting channel will read from the input stream and thus block until input is available or end of file is reached. Closing the channel will in turn cause the stream to be closed.

Parameters:

in - The stream from which bytes are to be read

Returns:

A new readable byte channel

newChannel

public static WritableByteChannel newChannel(OutputStream out)

Constructs a channel that writes bytes to the given stream.

The resulting channel will not be buffered; it will simply redirect its I/O operations to the given stream. Closing the channel will in turn cause the stream to be closed.

Parameters:

out - The stream to which bytes are to be written

Returns:

A new writable byte channel

newReader

public static Reader newReader(ReadableByteChannel ch,
 CharsetDecoder dec,
 int minBufferCap)

Constructs a reader that decodes bytes from the given channel using the given decoder.

The resulting stream will contain an internal input buffer of at least minBufferCap bytes. The stream's read methods will, as needed, fill the buffer by reading bytes from the underlying channel; if the channel is in non-blocking mode when bytes are to be read then an IllegalBlockingModeException will be thrown. The resulting stream will not otherwise be buffered, and it will not support the mark or reset methods. Closing the stream will in turn cause the channel to be closed.

Parameters:

ch - The channel from which bytes will be read

dec - The charset decoder to be used

minBufferCap - The minimum capacity of the internal byte buffer, or -1 if an implementation-dependent default capacity is to be used

Returns:

A new reader

newReader

public static Reader newReader(ReadableByteChannel ch,
 String csName)

Constructs a reader that decodes bytes from the given channel according to the named charset.

An invocation of this method of the form

    Channels.newReader(ch, csname)

behaves in exactly the same way as the expression

    Channels.newReader(ch, Charset.forName(csName))

Parameters:

ch - The channel from which bytes will be read

csName - The name of the charset to be used

Returns:

A new reader

Throws:

UnsupportedCharsetException - If no support for the named charset is available in this instance of the Java virtual machine

newReader

public static Reader newReader(ReadableByteChannel ch,
 Charset charset)

Constructs a reader that decodes bytes from the given channel according to the given charset.

An invocation of this method of the form

    Channels.newReader(ch, charset)

behaves in exactly the same way as the expression

    Channels.newReader(ch, charset.newDecoder(), -1)

The reader's default action for malformed-input and unmappable-character errors is to report them. When more control over the error handling is required, the constructor that takes a CharsetDecoder should be used.

Parameters:

ch - The channel from which bytes will be read

charset - The charset to be used

Returns:

A new reader

newWriter

public static Writer newWriter(WritableByteChannel ch,
 CharsetEncoder enc,
 int minBufferCap)

Constructs a writer that encodes characters using the given encoder and writes the resulting bytes to the given channel.

The resulting stream will contain an internal output buffer of at least minBufferCap bytes. The stream's write methods will, as needed, flush the buffer by writing bytes to the underlying channel; if the channel is in non-blocking mode when bytes are to be written then an IllegalBlockingModeException will be thrown. The resulting stream will not otherwise be buffered. Closing the stream will in turn cause the channel to be closed.

Implementation Note:

The value of minBufferCap is ignored.

Parameters:

ch - The channel to which bytes will be written

enc - The charset encoder to be used

minBufferCap - The minimum capacity of the internal byte buffer, or -1 if an implementation-dependent default capacity is to be used. The value of minBufferCap may be ignored

Returns:

A new writer

newWriter

public static Writer newWriter(WritableByteChannel ch,
 String csName)

Constructs a writer that encodes characters according to the named charset and writes the resulting bytes to the given channel.

An invocation of this method of the form

    Channels.newWriter(ch, csname)

behaves in exactly the same way as the expression

    Channels.newWriter(ch, Charset.forName(csName))

Parameters:

ch - The channel to which bytes will be written

csName - The name of the charset to be used

Returns:

A new writer

Throws:

UnsupportedCharsetException - If no support for the named charset is available in this instance of the Java virtual machine

newWriter

public static Writer newWriter(WritableByteChannel ch,
 Charset charset)

Constructs a writer that encodes characters according to the given charset and writes the resulting bytes to the given channel.

An invocation of this method of the form

    Channels.newWriter(ch, charset)

behaves in exactly the same way as the expression

    Channels.newWriter(ch, charset.newEncoder(), -1)

The writer's default action for malformed-input and unmappable-character errors is to report them. When more control over the error handling is required, the constructor that takes a CharsetEncoder should be used.

Parameters:

ch - The channel to which bytes will be written

charset - The charset to be used

Returns:

A new writer