The NIO and AIO of Java Foundation article

1. Synchronous and asynchronous

Synchronization: A task runs after the next task is run

Async: Start a new thread after receiving a task to run this task, basically do not occupy the original thread time

2. Blocking and non-blocking

Blocking: When multiple threads access a single piece of data at the same time, only one thread is accessing it and the other is waiting

Non-blocking: Multiple threads can access the same piece of data at the same time

3.nio and IO and AIO differences

NIO: Synchronous non-blocking

IO: Synchronous-blocking

AIO: Asynchronous non-blocking

Efficiency Io<nio<aio

4.buffer buffer: The corresponding data read and write operations

1) subclasses have Bytebuffer,charbuffer,floatbuffer,doublebuffer,intbuffer,longbuffer,shortbuffer, etc., But no Booleanbuffer (because Boolean only true and false is not good at determining its location)

2) 4 Core properties of buffer buffers

Capacity: capacity, representing the maximum amount of data stored in the buffer

Limit: The limit that indicates the size of the data that can be manipulated in the buffer (data after limit cannot read and write operations)

Position: Position representing the position in the buffer where the data is being manipulated

Mark: Mark the location of the current position record

3) Buffer method:

Capacity (): return capacity size = equals Set value

Clear (): Reset Accordingly, limit=capacity= set value position=0

Flip (): The position position becomes the data insertion starting point 0,limit becomes the end of the data insertion, the capacity is not changed, the put will generally use flip ()

Array (): Returns a corresponding array

Hasremaining (): Returns whether the upper bound limit has been reached and is typically used with while mates

Limit (int newlimit): Set upper bounds, generally used to calculate length

Position (int newposition): Set Position location

Remaining (): Returns the number of elements remaining from the position position to the upper bound position

Reset (): Sets the position at the mark () Mark position, in which case the reset is used in conjunction with the MAK

Rewind (): Set the position position to 0 and clear the mark mark

Isdirect (): Returns whether it is a direct buffer

IsReadOnly (): Returns whether this buffer is read-only

HasArray (): Whether this buffer returns an accessible array

4) Conversion between buffer subclasses, as ... , the capacity will make the corresponding byte-length transformation

5) Bytebuffer

Methods to get objects

Bytebuffer.allocate (int capacity): Non-direct buffer

Bytebuffer.allocatedirect (int capacity): Direct buffer

Bytebuffer.wrap (byte[] array): Non-direct buffer

Bytebuffer.wrap (byte[] array, int offset, int length): Non-direct buffer

Bytebuffer Common methods:

Get (byte[] DST): Get buffer Array contents

Get (int index): Gets the buffer content at the specified position

Order (): Gets the byte order of this buffer

Put (byte[] src): buffers are put into data by array

Put (byte B): buffers are placed into data by byte

put (int index, byte b): Place byte data in the specified position

6) General use steps

Create a Buffer object to define the initial capacity

Put put into data

Flip () flipping

Get () Get data

Clear () Reset

5. Channel channels: Connect the channel of the data source, the program cannot directly access the data in the channel, must interact with the Bytebuffer to access the data.

1) methods in the interface

Close (): Close of Channel

Isopen (): Returns whether the channel is open or closed

2) Implement Interface common class

Nio

FileChannel Class Datagramchannel class Serversocketchannel class Socketchannel class

Aio

Asynchronousfilechannel Class Asynchronousserversocketchannel Class Asynchronoussocketchannel class

3) NiO

FileChannel class

Common ways to get objects

Fileinputstream.getchannel ()

Fileoutputstream.getchannel ()

Randomaccessfile.getchannel ()

Filechannel.open (path Path, openoption ... options) (Path:paths.get (String URL),

Openoption ... Variable parameters

Subclass Standardopenoption Enum Type

Common values:

Append: Add at end of file

Create: If the file does not exist and the file is created, overwriting is present, this option ignores the CREATE_NEW option

Create_new: Create if not present, error if present

Write: Writing

READ: Reading)

Common methods:

Force (): Forces the content inside the channel to be written to the appropriate storage device, which is useful for saving data instantly when the system crashes

Lock (): Gets the exclusive lock of the channel (exclusive lock: One thread at a time, shared lock: Concurrent access to shared resources, allowing simultaneous access of licensed multiple threads, such as semaphore)

TransferTo (long position, long count, Writablebytechannel target): Writes a file to another file, similar to Transferform

read(ByteBuffer dst)：读取内容放入buffer缓冲区

read(ByteBuffer[] dst)：读取内容放入缓冲区数组，按先后顺序读（scatter）

Read (bytebuffer[] dsts, int offset, int length): reads the buffer of length array from offset and writes

Size (): Returns the file sizes

Truncate (long size): Intercepting files

Write (Bytebuffer src): Writes a file of buffer buffers

Write (bytebuffer[] srcs): Writes a file of buffer buffers array, in its order (gather)

Write (bytebuffer[] dsts, int offset, int length): reads the buffer of length array from offset and writes

General use steps

Creating objects

Create buffer cache

Reads the content loop read to the buffer

Flip () The corresponding rollover

Write the corresponding writing file

Clear () The corresponding reset, re-use buffer

To close the corresponding

Datagramchannel class

Common ways to get objects

Datagramchannel.open ()

Common methods

Bind (socketaddress Local): Bound port

Connect (socketaddress Remote): Connection port and Address

Disconnect (): Disconnected

IsConnected () Determine if it is connected

Receive (Bytebuffer DST): server-side Accept buffer content

Send (Bytebuffer src, socketaddress target): Sends buffer data to the specified address

Register (Selector sel, int ops): Registers a channel with a given selector, returns a key value

Configureblocking (Boolean block): Adjust blocking mode true blocking mode, false non-blocking mode using selectors requires non-blocking mode

General use steps

Creating Client Objects

Set to direct cache

Creating buffers

Cyclic read read

Flip for the corresponding rollover

Send the buffer, enter the appropriate IP address and port

Clear the corresponding reset buffer

The corresponding Closing object

Create the appropriate object on the server side

Set to direct cache

Bind the appropriate port

Creates a selector polling readiness state where the corresponding flip (), receive (buffer), and clear

Removing iterators

Serversocketchannel class

Common ways to get objects:

Serversocketchannel.open ()

Common methods:

Bind (socketaddress Local): Bound port

Register (Selector sel, int ops): Registers a channel with a given selector, returns a key value

Accept (): Accepts buffer contents

Configureblocking (Boolean block): Adjust blocking mode true blocking mode, false non-blocking mode using selectors requires non-blocking mode

Creating a service-side object

Change to direct cache

Binding port

Create selectors and poll-detect

Loop to read and write accordingly

Removing iterators

Socketchannel class

Common methods for getting objects

Socketchannel.open ()

Common methods

Connect (socketaddress remote): Ibid.

IsConnected (): Ibid.

Read (Bytebuffer DST): Ibid.

Write (Bytebuffer src): ibid.

Write (bytebuffer[] srcs): Ibid.

Write (bytebuffer[] srcs, int offset, int length): Ibid.

Configureblocking (Boolean block): Ibid.

General steps

Common channel objects, and connecting IP addresses and ports

Change to direct cache

Creating a Buffer Object

The corresponding loop flip () write (buffer) clear

Close Channel Object

Selector Selector

Common ways to get objects

Selector.open ()

Common methods

Select (): Swap back the number of buffers that are ready

Selectedkeys (): Keyset (selectedkey.op_connect: Connection Ready, Selectedkey.op_accept: Accept ready, Selectedkey.op_read read ready, Selectedkey.op _write write Ready)

Selectnow (): It's not ready now, it's over.

Select (Long timeout): Up to the end of waiting for timeout not ready

Close (): Close Selector

Selectedkey

IsReadable (): Ready to read

IsWritable (): Ready to write ready

Cancel (): Cancel the selector registration

Isacceptable (): Accept Readiness

Isconnectable (): Is the connection ready

Pipe piping

Sinkchannel Write operations

Sourcechannel Read operation

The rest is basically similar

4) AIO

Asynchronousfilechannel class

Common methods for commonly used objects

Asynchronousfilechannel.open ()

Asynchronousfilechannel. Open (Asynchronouschannelgroup Group): Binding thread pool, (thread pool handles two things: processing IO and distributing competition)

Common methods

Force (Boolean MetaData)

Lock ()

Read (Bytebuffer DST, long position)

Size ()

Truncate (long size)

Write (Bytebuffer src, long position)

Close ()

Asynchronousserversocketchannel class

Common object methods commonly used:

Asynchronousserversocketchannel.open ()

Asynchronousserversocketchannel.open (Asynchronouschannelgroup Group)

Common methods:

Accept ()

Bind (SocketAddress Local)

Asynchronoussocketchannel class

Common ways to get objects

Asynchronoussocketchannel. Open ()

Asynchronoussocketchannel. Open (Asynchronouschannelgroup Group)

Common methods

Bind (SocketAddress Local)

Connect (socketaddress remote)

Read (Bytebuffer DST)

Write (Bytebuffer src)

Shutdowninput ()

Shutdownoutput ()

The NIO and AIO of Java Foundation article