Asynchronous design
CallBack
Futures
NINE JDK1.4
NIO2 JDK1.7
Standard IO: characters and byte-stream oriented data
NIO: based channel (Channel) and buffer (Buffer), facing the buffer
Read operation: channel - Data -> Buffer
Write: Buffer - Data -> Channel
NIO core:
Buffer
Channel
Selector
Buffer memory fragments essentially, Buffer has three attributes: capacity, position, limit
capacity is the capacity in both the write mode, the write mode position and capacity meaning related Buffer
Buffer Write mode :
When default initialization position = 0, position Maximum = capacity-1
The maximum amount of data that can be written to limit capacity = buffer capacity
Buffer read mode :
position = 0, each reading, position rearward movement
limit = position when writing mode
Buffer's member variables :
capacity:int
limit:int
mark:int
position:int
Buffer's method:
clear():Buffer
flip():Buffer
Buffer's implementation class :
ByteBuffer，CharBuffer等
IO Model:
blocking IO
nonBlocking IO
IO multiplexing
asynchronous IO
Two objects associated with the network IO: process (OR thread) and kernel
Selector scheduler whether a plurality of nonblocking IO, examine one or more NIO Channel state in the readable, writable.
Selector achieve threaded manage multiple Channels, i.e. managing multiple network connections.
Selector belong case of IO multiplexing
Selector.select () polling Find
Channels of four states:
Connect
Accept
Read
Write
SelectionKey corresponding to the four states:
SelectionKey.OP_CONNECT
SelectionKey.OP_ACCEPT
SelectionKey.OP_READ
SelectionKey.OP_WRITE
Java IO
Essence character streams: byte stream read + check code table (code table according to the character mapping)
And the node relationship process flow stream: flow packaging process flow nodes, using the decorative design pattern, to eliminate the difference node stream.
Encoding and decoding
Coding: plaintext character sequence ----> binary sequence of bytes
Decoding: a binary sequence of bytes ----> plaintext character sequence
Netty in:
Encoding: Java objects ----> byte
Decoding: Byte ----> Java Objects
A series of bytes of data network.
Common strings and application / x-www-form-urlencoded MIME string
URLDecoder
URLEncoder