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This article introduces how websocket and the lower computer communicate and transmit behavior information through netty, the content is very detailed, interested friends can refer to, hope to be helpful to you.

Introduction to the preface

In the development of the Internet of things, it is often necessary to control devices through the web, including obtaining information, performing operations, starting and stopping, etc., just as we control some devices such as millet boxes, routers, rice cookers or online dogs at home on our mobile phones. Here, all the lower-layer devices can be linked to the server through socket communication, while the user side is linked to the server through http link or websocket link, and makes corresponding actions by sending and receiving data. The figure below is as follows

Official account of Wechat: bugstack wormhole stack & execution process

Case goal

This chapter integrates Springboot+Netty and receives forwarding behavior messages by deploying two servers, nettySocket and webSocket.

The client uses js link websocket to receive server feedback and send instructions to obtain the information of the lower computer.

Start an analog lower computer in test for feedback of information and data. In real development, the communication between the lower computer and the server is usually a well-defined bytecode, so we need to write our own decoder.

Environmental preparation

Jdk 1.8.0

IntelliJ IDEA Community Edition 2018.3.1 x64

Netty 4.1.36.Final

Code sample 1itstack-demo-netty-3-01

2 └── src

3 ├── main

4 │ ├── java

5 │ │ └── org.itstack.demo.ark

6 │ │ ├── domain

7 │ ├── msgobj

8 │ ├── Feedback.java

9 │ ├── QueryInfoReq.java

10 │ └── Text.java

11 │ ├── Device.java

12 │ ├── EasyResult.java

13 │ ├── InfoProtocol.java

14 │ └── ServerInfo.java

15 │ │ ├── server

16 │ ├── socket

17 │ ├── MyChannelInitializer.java

18 │ ├── MyServerHandler.java

19 │ └── NettyServer.java

20 │ └── websocket

21 │ ├── MyWsChannelInitializer.java

22 │ ├── MyWsServerHandler.java

23 │ └── WsNettyServer.java

24 │ │ ├── util

25 │ ├── CacheUtil.java

26 │ ├── MsgUtil.java

27 │ └── MsgUtil.java

28 │ │ ├── web

29 │ └── NettyController.java

30 │ │ └── Application.java

31 │ └── resources

32 │ │ └── application.yml

33 │ └── webapp

34 │ ├── arkWs

35 │ │ ├── js

36 │ └── ws.js

37 │ │ └── arkWsControlCenter.html

38 │ ├── res

39 │ └── WEB-INF

40 │ └── index.jsp

41 │

42 └── test

43 └── java

44 └── org.itstack.demo.test

45 └── ApiTest.java

Demo part of the key code block, complete code download follow official account; bugstack wormhole stack, reply to Netty case

Server/socket/MyServerHandler.java & socket data processing

When there is a lower computer link server, the lower computer information is built, and the actual use can be verified by registration.

When the information of the lower computer is received, it is forwarded to the websocket side, so that the web page side receives the feedback of the lower computer information.

1public class MyServerHandler extends ChannelInboundHandlerAdapter {

two

3 private Logger logger = LoggerFactory.getLogger (MyServerHandler.class)

four

5 / *

6 * this channel becomes active when the client actively links the link on the server. That is, the client and the server establish a communication channel and can transmit data.

7 * /

8 @ Override

9 public void channelActive (ChannelHandlerContext ctx) throws Exception {

10 SocketChannel channel = (SocketChannel) ctx.channel ()

11 String channelId = channel.id () .toString ()

12 System.out.println ("Link report start")

13 System.out.println ("Link report information: a client is linked to this server. ChannelId:" + channelId)

14 System.out.println ("linked report IP:" + channel.localAddress () .getHostString ())

15 System.out.println ("linked report Port:" + channel.localAddress () .getPort ())

16 System.out.println ("link report completed")

seventeen

18 / / build equipment information {lower machine, repeater, IO board}

19 Device device = new Device ()

20 device.setChannelId (channelId)

21 device.setNumber (UUID.randomUUID () .toString ())

22 device.setIp (channel.remoteAddress (). GetHostString ())

23 device.setPort (channel.remoteAddress () .getPort ())

24 device.setConnectTime (new Date ())

25 / / add device information

26 deviceGroup.put (channelId, device)

27 CacheUtil.cacheClientChannel.put (channelId, channel)

28}

twenty-nine

thirty

31 @ Override

32 public void channelRead (ChannelHandlerContext ctx, Object objMsgJsonStr) throws Exception {

33 / / A message from the receiving device

34 System.out.println (new SimpleDateFormat ("yyyy-MM-dd HH:mm:ss") .format (new Date ()) + "received message content:" + objMsgJsonStr)

thirty-five

36 / / forward messages to Ws

37 CacheUtil.wsChannelGroup.writeAndFlush (new TextWebSocketFrame (objMsgJsonStr.toString ()

38}

thirty-nine

40}

Server/websocket/MyWsServerHandler.java & websocket data processing

Websocket data needs to be used after conversion and can support text messages. In this case, json strings are used to facilitate object transmission.

ChannelRead forwards the data, when it receives the data, it sends it to the lower computer, which is mainly controlled by channel in the content.

1public class MyWsServerHandler extends ChannelInboundHandlerAdapter {

two

three

4 @ Override

5 public void channelRead (ChannelHandlerContext ctx, Object msg) throws Exception {

six

7...

eight

9 / / ws

10 if (msg instanceof WebSocketFrame) {

11 WebSocketFrame webSocketFrame = (WebSocketFrame) msg

12 / / close the request

13 if (webSocketFrame instanceof CloseWebSocketFrame) {

14 handshaker.close (ctx.channel (), (CloseWebSocketFrame) webSocketFrame.retain ())

15 return

16}

17 / / ping request

18 if (webSocketFrame instanceof PingWebSocketFrame) {

19 ctx.channel () .write (new PongWebSocketFrame (webSocketFrame.content () .retain ()

20 return

21}

22 / / only text format is supported, not binary messages

23 if (! (webSocketFrame instanceof TextWebSocketFrame)) {

24 throw new Exception ("text formatting only")

25}

twenty-six

27 String request = (TextWebSocketFrame) webSocketFrame) .text ()

28 System.out.println ("Server receives:" + request)

29 InfoProtocol infoProtocol = JSON.parseObject (request, InfoProtocol.class)

30 / / socket forward messages

31 String channelId = infoProtocol.getChannelId ()

32 Channel channel = CacheUtil.cacheClientChannel.get (channelId)

33 if (null = = channel) return

34 channel.writeAndFlush (MsgUtil.buildMsg (infoProtocol))

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36 / / websocket message feedback was sent successfully

37 ctx.writeAndFlush (MsgUtil.buildWsMsgText (ctx.channel (). Id (). ToString (), "convey a message to the lower computer success!"))

38}

thirty-nine

40}

forty-one

42}

Web/NettyController.java & the control layer facilitates access to server-side information

The control layer provides query service list, linked device information, and active trigger message sending.

In addition, if you need to manually control the startup and shutdown of the server, you can provide a method to call here.

1@Controller

2public class NettyController {

three

4 private Logger logger = LoggerFactory.getLogger (NettyController.class)

five

6 @ RequestMapping ("/ index")

7 public String index () {

8 return "index"

9}

ten

11 @ RequestMapping ("/ queryNettyServerList")

12 @ ResponseBody

13 public Collection queryNettyServerList () {

14 try {

15 Collection serverInfos = CacheUtil.serverInfoMap.values ()

16 logger.info ("query server list. {}", JSON.toJSONString (serverInfos))

17 return serverInfos

18} catch (Exception e) {

19 logger.info ("failed to query server list." , e)

20 return null

21}

22}

twenty-three

24 @ RequestMapping ("/ queryDeviceList")

25 @ ResponseBody

26 public Collection queryDeviceList () {

27 try {

28 Collection deviceInfos = CacheUtil.deviceGroup.values ()

29 logger.info ("query list of device links. {}", JSON.toJSONString (deviceInfos))

30 return deviceInfos

31} catch (Exception e) {

32 logger.info ("failed to query the list of device links." , e)

33 return null

34}

35}

thirty-six

37 @ RequestMapping ("/ doSendMsg")

38 @ ResponseBody

39 public EasyResult doSendMsg (String reqStr) {

40 try {

41 logger.info ("send information to the device [you can call this API through another Web service]: {}", reqStr)

42 InfoProtocol infoProtocol = MsgUtil.getMsg (reqStr)

43 String channelId = infoProtocol.getChannelId ()

44 Channel channel = CacheUtil.cacheClientChannel.get (channelId)

45 channel.writeAndFlush (MsgUtil.buildMsg (infoProtocol))

46 return EasyResult.buildSuccessResult ()

47} catch (Exception e) {

48 logger.error ("failed to send message to device: {}", reqStr, e)

49 return EasyResult.buildErrResult (e)

50}

51}

fifty-two

53}

Application.java & initiator layer

Start the socket service when the service is ready by inheriting the CommandLineRunner method

After startup, you need to cycle through to verify whether the startup is complete.

1@SpringBootApplication

2@ComponentScan ("org.itstack.demo.ark")

3public class Application implements CommandLineRunner {

four

5 private Logger logger = LoggerFactory.getLogger (Application.class)

six

7 @ Value ("${netty.socket.port}")

8 private int nettyServerPort

9 @ Value ("${netty.websocket.port}")

10 private int nettyWsServerPort

11 / / default thread pool

12 private static ExecutorService executorService = Executors.newFixedThreadPool (2)

thirteen

14 public static void main (String [] args) {

15 SpringApplication.run (Application.class, args)

16}

seventeen

18 @ Override

19 public void run (String... Args) throws Exception {

20 / / start NettyServer-socket

21 logger.info ("start NettyServer service, startup port: {}", nettyServerPort)

22 NettyServer nettyServer = new NettyServer (new InetSocketAddress (nettyServerPort))

23 Future future = executorService.submit (nettyServer)

24 Channel channel = future.get ()

25 if (null = = channel) {

26 throw new RuntimeException ("netty server-s open error channel is null")

27}

28 while (! channel.isActive ()) {

29 logger.info ("start the NettyServer service, loop waiting to start...")

30 Thread.sleep

31}

32 logger.info ("start NettyServer service, complete: {}", channel.localAddress ())

33 CacheUtil.serverInfoMap.put (nettyServerPort, new ServerInfo ("NettySocket", NetUtil.getHost (), nettyServerPort, new Date ()

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35 / / start NettyServer-websocket

36 logger.info ("start NettyWsServer service, startup port: {}", nettyWsServerPort)

37 WsNettyServer wsNettyServer = new WsNettyServer (new InetSocketAddress (nettyWsServerPort))

38 Future wsFuture = executorService.submit (wsNettyServer)

39 Channel wsChannel = wsFuture.get ()

40 if (null = = wsChannel) {

41 throw new RuntimeException ("netty server-ws open error channel is null")

42}

43 while (! wsChannel.isActive ()) {

44 logger.info ("start the NettyWsServer service, loop waiting to start...")

45 Thread.sleep

46}

47 logger.info ("start NettyWsServer service, complete: {}", wsChannel.localAddress ())

48 CacheUtil.serverInfoMap.put (nettyServerPort, new ServerInfo ("NettyWsSocket", NetUtil.getHost (), nettyServerPort, new Date ()

49}

fifty

51}

Webapp/arkWs/js/ws.js & Link websocket server

1socket = new WebSocket ("ws://localhost:7398/websocket")

two

3 socket.onmessage = function (event) {

four

5 var msg = JSON.parse (event.data)

6 console.info (msg)

seven

8 $("# msgBox") .val ($("# msgBox") .val () + event.data + "\ r\ n")

nine

10}

Case testing

Start the following respectively

Application.java,Plugins/spring-boot/spring-boot:run

ApiTest.java, right start the analog lower computer

Open the server link; http://localhost:8080/ http://localhost:8080/arkWs/arkWsControlCenter.html

Official account of Wechat: bugstack wormhole stack & server and monitoring

Send simulation information and observe the execution result

12019-12-01 15 Initializing Spring FrameworkServlet 11V 49.965 INFO 7620-[nio-8080-exec-1] o.a.c.c..[ tomcat] .[ localhost]. [/]: tomcat 'dispatcherServlet'

22019-12-01 15 o.s.web.servlet.DispatcherServlet 1114 49.965 INFO 7620-[nio-8080-exec-1] o.s.web.servlet.DispatcherServlet: FrameworkServlet 'dispatcherServlet': initialization started

32019-12-01 15 o.s.web.servlet.DispatcherServlet 11 FrameworkServlet 49.980 INFO 7620-[nio-8080-exec-1] o.s.web.servlet.DispatcherServlet: FrameworkServlet 'dispatcherServlet': initialization completed in 15 ms

42019-12-01 15 o.itstack.demo.ark.web.NettyController 11V 51.157 INFO 7620-[nio-8080-exec-3] o.itstack.demo.ark.web.NettyController: query the list of device links. [{"channelId": "281d1279", "connectTime": 1575184302964, "ip": "127.0.0.1", "number": "74de0967-c0b4-4426-a9d1-183feaff2acf", "port": 3972}]

52019-12-01 15 INFO 111.162 INFO 7620-[io-8080-exec-10] o.itstack.demo.ark.web.NettyController: query server list. [{"ip": "10.13.70.50", "openDate": 1575184290501, "port": 7397, "typeInfo": "NettyWsSocket"}]

62019-12-01 15 o.i.d.a.s.websocket.MyWsServerHandler 11V 58.476 INFO 7620-[ntLoopGroup-7-1] o.i.d.a.s.websocket.MyWsServerHandler: link report begins

72019-12-01 15 o.i.d.a.s.websocket.MyWsServerHandler 11V 58.476 INFO 7620-[ntLoopGroup-7-1] o.i.d.a.s.websocket.MyWsServerHandler: link report message: there is a client linked to this server

82019-12-01 15 o.i.d.a.s.websocket.MyWsServerHandler 11V 58.476 INFO 7620-[ntLoopGroup-7-1] o.i.d.a.s.websocket.MyWsServerHandler: link report IP:0:0:0:0:0:0:0:1

92019-12-01 15 o.i.d.a.s.websocket.MyWsServerHandler 11V 58.476 INFO 7620-[ntLoopGroup-7-1] o.i.d.a.s.websocket.MyWsServerHandler: link report Port:7398

102019-12-01 15 o.i.d.a.s.websocket.MyWsServerHandler 11V 58.476 INFO 7620-[ntLoopGroup-7-1] o.i.d.a.s.websocket.MyWsServerHandler: link report completed

11 the server receives: {"channelId": "281d1279", "msgType": 2, "msgObj": {"stateType": "1"}}

122019-12-01 15:12:05 received message content: {"msgObj": {"stateMsg": "temperature information: 91.313348941763 °C", "stateType": 1, "channelId": "93c1120a"}, "msgType": 3, "channelId": "93c1120a"}

13 the server receives: {"channelId": "281d1279", "msgType": 2, "msgObj": {"stateType": "1"}}

142019-12-01 15:12:05 received message content: {"msgObj": {"stateMsg": "temperature information: 44.83794772946285 °C", "stateType": 1, "channelId": "93c1120a"}, "msgType": 3, "channelId": "93c1120a"}

To sum up

In the use of springboot and netty combination, the development of a simple server is very convenient, and in the collection of some springcloud services, can make the project more perfect.

You can try to do some device control services, and you can also control the equipment at home through an H6 link when we are not at home, such as turning on the water heater when we get home soon.

This case is also biased towards simulation, in the actual development process, there will still be a lot of business problems to be solved, especially the communication between the server and the lower computer, the need to write encoders and decoders.

On the websocket and the lower computer how to communicate and transmit behavior information through netty way to share here, I hope the above content can be of some help to you, can learn more knowledge. If you think the article is good, you can share it for more people to see.

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