The central abstractions of the NIO APIs are:
* *Buffers, which are containers for data; *
Charsets and their
* associated decoders and encoders,
which translate between
* bytes and Unicode characters;
Channels of
* various types, which represent connections
to entities capable of
* performing I/O operations; and
Selectors and selection keys, which together with
* selectable channels define a multiplexed, non-blocking
* I/O facility.
The java.nio package defines the buffer classes, which are used
* throughout the NIO APIs. The charset API is defined in the {@link
* java.nio.charset} package, and the channel and selector APIs are defined in the
* {@link java.nio.channels} package. Each of these subpackages has its own
* service-provider (SPI) subpackage, the contents of which can be used to extend
* the platform's default implementations or to construct alternative
* implementations.
*
*
*
*
* Buffers Description A buffer is a container for a fixed amount of data of a specific
* primitive type. In addition to its content a buffer has a position,
* which is the index of the next element to be read or written, and a
* limit, which is the index of the first element that should not be read
* or written. The base {@link java.nio.Buffer} class defines these properties as
* well as methods for clearing, flipping, and rewinding, for
* marking the current position, and for resetting the position to
* the previous mark.
*
* There is a buffer class for each non-boolean primitive type. Each class
* defines a family of get and put methods for moving data out of
* and in to a buffer, methods for compacting, duplicating, and
* slicing a buffer, and static methods for allocating a new buffer
* as well as for wrapping an existing array into a buffer.
*
* Byte buffers are distinguished in that they can be used as the sources and
* targets of I/O operations. They also support several features not found in the
* other buffer classes:
*
* A byte buffer can be allocated as a
* direct buffer, in which case the Java virtual machine will make a
* best effort to perform native I/O operations directly upon it. A byte buffer can be created by {@link
* java.nio.channels.FileChannel#map mapping A byte buffer provides access to its content as either a heterogeneous
* or homogeneous sequence of binary data
* of any non-boolean primitive type, in either big-endian or little-endian byte order. Unless otherwise noted, passing a null argument to a constructor
* or method in any class or interface in this package will cause a {@link
* java.lang.NullPointerException NullPointerException} to be thrown.
*
* @since 1.4
* @author Mark Reinhold
* @author JSR-51 Expert Group
*/
*
*
*
{@link java.nio.Buffer}
* Position, limit, and capacity;
*
clear, flip, rewind, and mark/reset {@link java.nio.ByteBuffer}
* Get/put, compact, views; allocate, wrap {@link java.nio.MappedByteBuffer}
* A byte buffer mapped to a file {@link java.nio.CharBuffer}
* Get/put, compact; allocate, wrap {@link java.nio.DoubleBuffer}
* ' ' {@link java.nio.FloatBuffer}
* ' ' {@link java.nio.IntBuffer}
* ' ' {@link java.nio.LongBuffer}
* ' ' {@link java.nio.ShortBuffer}
* ' ' {@link java.nio.ByteOrder}
* Typesafe enumeration for byte orders
*
*
*
* } a region of a
* file directly into memory, in which case a few additional file-related
* operations defined in the {@link java.nio.MappedByteBuffer} class are
* available.