浅析websocket的基本应用spring boot + vue +C# + WPF

1.基本概念

首先websocket是基于H5的一种通信。在网页中如果定时获取服务器端的实时数据，我们常采用long poll 和ajax轮询的方式。但是在轮询过程中，由于根本没有新数据的改变，而造成一种资源的浪费，同时也不能够保证数据的实时性。long poll是一种保持长连接的方式获取数据，但是需要进行头文件的各种校验，也是一种资源的浪费。

websocket完美的解决了这种两种方式的不足，首先能够保证数据的实时性，同时保证资源的完整利用，是网页和服务端的全双工通信，即可以接收来自网页端的消息，同时可以发送通知网页端。websocket还支持多种方式，本篇讨论java，C#(WPF)和vue，即服务端为java,客户端分别为vue和WPF来进行验证。

2.基本原理

websocket是基于TCP的一种通信，所以在建立通信之前首先需要建立TCP的一系列连接（三次握手等）。

服务端采用Springboot来实现，首先在pom.xml中添加WebSocect的依赖

      <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-websocket</artifactId>
        </dependency>

　　接下来建立WebSocket并实现ServerEndPoint  我这里采用注解的方式

package com.koalin.rpc.websocket;

import com.utils.DateTimeUtils;
import org.springframework.stereotype.Component;

import javax.websocket.OnClose;
import javax.websocket.OnMessage;
import javax.websocket.OnOpen;
import javax.websocket.Session;
import javax.websocket.server.PathParam;
import javax.websocket.server.ServerEndpoint;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.CopyOnWriteArraySet;


/**
 * @version 1.0
 * @ClassName WebSocket
 * @Author koalin
 * @Description //TODO WebSocket的描述
 * @Date 2019/12/24 23:27
 */
@ServerEndpoint("/koalin/websocket/{userName}")
@Component
public class WebSocket {
    private Session session;
    private static CopyOnWriteArraySet<WebSocket> webSockets = new CopyOnWriteArraySet<>();

    private static Map<String, Session> sessionPool = new HashMap<String, Session>();
    volatile static boolean isRunning = false;
    private String userName;

    @OnOpen
    public void onOpen(Session session, @PathParam(value = "userName") String userName) {
        this.session = session;
        this.userName = userName;
        webSockets.add(this);
        sessionPool.put(session.getId(), session);
        System.out.println(userName + "【websocket消息】有新的连接，总数为:" + webSockets.size());

        if (webSockets.size()==1) {
            isRunning = true;
            new Runnable() {
                @Override
                public void run() {
                    while (true) {
                        try {
                            for (WebSocket client :
                                    webSockets) {
                                String msg = "Hello I am WebSocekt " + client.userName + "我的时间：" + DateTimeUtils.DateTimeYYYYMMDDHHMMSS(new Date());
                                client.session.getAsyncRemote().sendText(msg);
                                System.out.println(msg);

                                Thread.sleep(2000);
                            }
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                            isRunning=false;
                        }

                    }
                }
            }.run();
        }
    }

    @OnClose
    public void onClose() {
       if (webSockets.contains(this) ){
        webSockets.remove(this);
        System.out.println(this.userName+"【websocket消息】连接断开，总数为:" + webSockets.size());
       }

    }

    @OnMessage
    public void onMessage(String message,Session session) {
        //System.out.println("【websocket消息】收到客户端消息:" + message);
        System.out.println("【websocket消息】收到客户端消息:" + message);
    }

    // 此为广播消息
    public void sendAllMessage(String message) {
        for (WebSocket webSocket : webSockets) {
            System.out.println("【websocket消息】广播消息:" + message);
            try {
                webSocket.session.getAsyncRemote().sendText(message);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    // 此为单点消息
    public void sendOneMessage(String userName, String message) {
        System.out.println("【websocket消息】单点消息:" + message);
        Session session = sessionPool.get(userName);
        if (session != null) {
            try {
                session.getAsyncRemote().sendText(message);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

}

添加WebSocketConfig 创建默认的EndPointServer

package com.koalin.rpc.websocket;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.server.standard.ServerEndpointExporter;

/**
 * @version 1.0
 * @ClassName WebSocketConfig
 * @Author koalin
 * @Description //TODO WebSocketConfig的描述
 * @Date 2019/12/24 23:36
 */
@Configuration
public class WebSocketConfig {

    /**
     * @return
     * @Author koalin
     * @Description //TODO这个bean会自动注册使用了@ServerEndpoint注解声明的Websocket endpoint
     * @Date 22:47 2019/12/24
     * @Param
     **/
    @Bean
    public ServerEndpointExporter serverEndpointExporter() {
        return new ServerEndpointExporter();
    }
}

以上完成服务端代码

接下来先验证C#客户端

首选在nuget中下载websocket-sharp

创建WebSocketClient

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using WebSocketSharp;

namespace WebSocketLib
{
    public class WebSocketClient
    {
        private WebSocket ws;
        private string url = "";
        CancellationToken token = new CancellationToken();
        public WebSocketClient(string url)
        {

            this.url = url;
        }

        public void Start()
        {

            try
            {
                ws = new WebSocket(url, token, 102392,
                      () =>
                      {//OnOpen
                          return Task.Run(() =>
                          {
                              Console.WriteLine("websocket连接正常....");
                          });
                      },
                      (e) =>
                      {//OnClose
                          return Task.Run(() =>
                          {
                              Console.WriteLine("websocket关闭正常...");
                          });
                      },
                      (e) =>
                      {//OnMessage
                          return Task.Run(() =>
                          {
                              Console.WriteLine("接收到服务端的消息" + e.Text.ReadToEnd());
                          });
                      },
                      (e) =>
                      {//OnError
                          return Task.Run(() =>
                          {
                              Console.WriteLine("连接异常..." + e.Message);
                          });
                      }
                      );

                ws.Connect();
            }
            catch (Exception e)
            {

                Console.WriteLine(e.ToString());
            }
        }

 public void StartSendMessage()
        {

            Task.Run(async () =>
            {
                await Task.Delay(1000);
                while (true)
                {
                    try
                    {
                        if (ws != null )  
                        {

                             Task<bool> tast= ws.Send(("HI i am C# client"+DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss")));

                             Console.WriteLine(tast.Result); 
                        }
                    }
                    catch (Exception ex)
                    {

                    }
                    await Task.Delay(2000);
                }
            });
        }

public void Close()
        {
            if (ws!=null)
            {
                ws.Close();
                ws.Dispose();
            }
        }
    }
}

简单的建立wpf窗体应用程序然后添加引用

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace WebSocketDemo
{
    /// <summary>
    /// MainWindow.xaml 的交互逻辑
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();


        }
        WebSocketLib.WebSocketClient client = null;
        private void Test()
        {

          client = new WebSocketLib.WebSocketClient("ws://www.koalin.com:8081/koalin/websocket/test");

            client.Start();

            
            client.StartSendMessage();
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            Test();
        }

        protected override void OnClosed(EventArgs e)
        {
            if (client!=null)
            {
                client.Close();
                
            }
            base.OnClosed(e);
        }
    }
}

　　启动服务和客户端进行简单的验证

建立vue工程，然后添加如下websockt关键代码

initWebSocket () {

        // 连接错误
        this.websocket.onerror = this.setErrorMessage
        // 连接成功
        this.websocket.onopen = this.setOnopenMessage
        // 收到消息的回调
        this.websocket.onmessage = this.setOnmessageMessage
        // 连接关闭的回调
        this.websocket.onclose = this.setOncloseMessage
        // 监听窗口关闭事件，当窗口关闭时，主动去关闭websocket连接，防止连接还没断开就关闭窗口，server端会抛异常。
        window.onbeforeunload = this.onbeforeunload
      },
      setErrorMessage () {
        console.log('WebSocket连接发生错误   状态码：' + this.websocket.readyState)
      },
      setOnopenMessage () {
        console.log('WebSocket连接成功    状态码：' + this.websocket.readyState)

        
      },
      setOnmessageMessage (event) {
        // 根据服务器推送的消息做自己的业务处理
        console.log('服务端返回：' + event.data)
      },
      setOncloseMessage () {
        console.log('WebSocket连接关闭    状态码：' + this.websocket.readyState)
      },
      onbeforeunload () {
        this.closeWebSocket()
      },
      
      closeWebSocket () {
        this.websocket.close()
      }
      },
  mounted() {
    this.restaurants = this.loadAll();
// WebSocket
      if ('WebSocket' in window) {
      // var url='ws://www.koalin.com:8081/koalin/websocket/' + new Date();
        this.websocket = new WebSocket('ws://www.koalin.com:8081/koalin/websocket/' + new Date());
       console.log(  this.websocket);
        this.initWebSocket();
      } else {
        alert('当前浏览器 Not support websocket')
      }
  },
  beforeDestroy () {

      this.onbeforeunload()

    }

启动vue服务。然后在网页中输入对应的链接。

 完成简单的客户端与服务端的通信