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This article mainly explains "how to achieve the function of Netty". The content of the explanation is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "how to achieve the function of Netty".

Netty is the framework that was first learned at the beginning of the year. The recent book rental system wants to use the chat function to achieve one-to-one dialogue chat. When the user logs in to the server, the user ip is bound to id and put into the channelgroup. Each cycle traverses the corresponding channel of the ip, otherwise, the false is returned, and the online status belongs to the handler message function.

1. One-on-one chat

two。 Show the number of people online

3. Login authentication

4. Input box optimization

5. Can support expression

Long live open source

When looking for the implementation of Netty one-to-one chat function, in addition to reviewing the function points, you can also find something new, a small demo, but others do not do so, refined to verification, but also take into account the performance, take a look at the implementation effect page

Nickname input is required. After login, it is not a simple addition of data.

Private static ReentrantReadWriteLock rwLock = new ReentrantReadWriteLock (true); private static ConcurrentMap userInfos = new ConcurrentHashMap (); private static AtomicInteger userCount = new AtomicInteger (0)

Read-write lock

Concurrent packet

Atomic counting

Because the online statistics of users are finally realized, atomic AtomicInteger is used.

Private static AtomicInteger uidGener = new AtomicInteger (1000)

Private boolean isAuth = false; / / whether to authenticate private long time = 0; / / login time private int userId; / / UID private String nick; / / nickname private String addr; / / address private Channel channel;// channel

Log in to the user information, determine the nickname, get the ip, and put each user ip,channel into the channelGroup one by one.

How do I send a message?

In message processing Handler, override the channelread0 method

1. Gets whether the channel of this user information exists

two。 There is a broadcast of user id, nickname, and received messages to the page for display.

3. Message is not null, read-write lock is added, and the current user's channel is found.

4. Traverses the user information and returns it through the netty write callback

If (msg instanceof FullHttpRequest) {handleHttpRequest (ctx, (FullHttpRequest) msg);} else if (msg instanceof WebSocketFrame) {handleWebSocket (ctx, (WebSocketFrame) msg);}

Connect Handler acceptance to Server

1. Timed shutdown of failed channel

two。 Regularly send ping messages to the client

Message processing flow of Netty

Define the parent-child thread group-> define the relevant processing channel processor in childInitializer-- > provide your own processor in the callback

Now start the callback.

.childHandler (new ChannelInitializer () {

@ Override protected void initChannel (SocketChannel ch) throws Exception {put group into the message pipeline ch.pipeline () .addLast (defLoopGroup, / / request decoder new HttpServerCodec () / / convert multiple messages into a single message object new HttpObjectAggregator (65536), / / support sending large code streams asynchronously Generally used to send file stream new ChunkedWriteHandler (), / / detect whether the link reads idle new IdleStateHandler (60,0,0), / / handle handshake and authentication new UserAuthHandler () / / send new MessageHandler for processing messages () })

Regular processing of failure messages

/ / scan all Channel regularly and close the failed Channel executorService.scheduleAtFixedRate (new Runnable () {@ Override public void run () {logger.info ("scanNotActiveChannel -"); UserInfoManager.scanNotActiveChannel ();}}, 3,60, TimeUnit.SECONDS)

/ / regularly send Ping messages executorService.scheduleAtFixedRate (new Runnable () {@ Override public void run () {UserInfoManager.broadCastPing ();}}, 3,50, TimeUnit.SECONDS) to all clients.

The front-end page hasn't changed much.

1. Bind websocket

2.websocket calls onmessage to process messages

Window.socket = new WebSocket ("ws://localhost:9688/websocket")

Processing technology:

1. Thread pool

2.Lambad expression

3. Read-write locks improve performance

4. Atomic reference ensures atomicity and thread safety

Debug

The user logs in to determine whether it is a given message type

Get nickname, user information, code

= = success, save user information

Do not log in for the first time without this user id and channel, do not broadcast messages

User count 0 broadCastPing userCount: 0

When sending a message to the page

Trigger a scheduled message broadcast to traverse the size

Processing message ctx.fireChannelRead (frame.retain ())

At this time, broadcast user count broadCastPing userCount: 1

Websocket realizes a real long connection between the client and the server, saving bandwidth and focusing on the content itself.

Websocket:1--: bidirectional data transfer

2Murray: based on Http

3Murray: non-browser situations

Thank you for your reading, the above is the content of "how to achieve Netty function", after the study of this article, I believe you have a deeper understanding of how to achieve Netty function, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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