websocket

 filter

package  com.dyh.filter;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;

@WebFilter(urlPatterns = "/*")
public class MyFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest req= (HttpServletRequest) servletRequest;
        System.out.println(req.getRequestURI());
        System.out.println(req.getSession().getId());
        filterChain.doFilter(servletRequest,
                servletResponse);
    }

    @Override
    public void destroy() {

    }
}

GetHttpSessionConfigurator

package com.dyh.websocket;

import javax.servlet.http.HttpSession;
import javax.websocket.HandshakeResponse;
import javax.websocket.server.HandshakeRequest;
import javax.websocket.server.ServerEndpointConfig;

public  class GetHttpSessionConfigurator extends ServerEndpointConfig.Configurator {
    @Override
    public void modifyHandshake(ServerEndpointConfig sec, HandshakeRequest request, HandshakeResponse response) {
        HttpSession httpSession=(HttpSession) request.getHttpSession();
        sec.getUserProperties().put(HttpSession.class.getName(),httpSession);
    }
}

WebSocket

package com.dyh.websocket;

import javax.servlet.http.HttpSession;
import javax.websocket.*;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.concurrent.CopyOnWriteArraySet;

/**
 * @ServerEndpoint 注解是一个类层次的注解，它的功能主要是将目前的类定义成一个websocket服务器端,
 * 注解的值将被用于监听用户连接的终端访问URL地址,客户端可以通过这个URL来连接到WebSocket服务器端
 */

@ServerEndpoint(value = "/websocket", configurator = GetHttpSessionConfigurator.class)
public class WebSocketTest {
    //静态变量，用来记录当前在线连接数。应该把它设计成线程安全的。
    private static int onlineCount = 0;

    //concurrent包的线程安全Set，用来存放每个客户端对应的MyWebSocket对象。若要实现服务端与单一客户端通信的话，可以使用Map来存放，其中Key可以为用户标识
    private static CopyOnWriteArraySet<WebSocketTest> webSocketSet = new CopyOnWriteArraySet<WebSocketTest>();

    //与某个客户端的连接会话，需要通过它来给客户端发送数据
    private Session session;
    private HttpSession httpSession;

    /**
     * 连接建立成功调用的方法
     * @param session  可选的参数。session为与某个客户端的连接会话，需要通过它来给客户端发送数据
     */
    @OnOpen
    public void onOpen(Session session,EndpointConfig config){
        this.session = session;
        this.httpSession = (HttpSession) config.getUserProperties().get(HttpSession.class.getName());
        webSocketSet.add(this);     //加入set中
        addOnlineCount();           //在线数加1
        System.out.println("有新连接["+session.getId()+"]所在会话["+httpSession.getId()+"]加入！当前在线人数为" + getOnlineCount());
    }

    /**
     * 连接关闭调用的方法
     */
    @OnClose
    public void onClose(){
        webSocketSet.remove(this);  //从set中删除
        subOnlineCount();           //在线数减1
        System.out.println("有一连接关闭！当前在线人数为" + getOnlineCount());
    }

    /**
     * 收到客户端消息后调用的方法
     * @param message 客户端发送过来的消息
     * @param session 可选的参数
     */
    @OnMessage
    public void onMessage(String message, Session session) {
        System.out.println("来自客户端的消息:" + message);
        //群发消息
        for(WebSocketTest item: webSocketSet){
            if(item==this || item.httpSession==this.httpSession) continue;
            try {
                item.sendMessage("<img src=1.png>"+  message);
            } catch (Exception e) {
                System.err.println(e.getMessage());
                continue;
            }
        }
    }

    /**
     * 发生错误时调用
     * @param session
     * @param error
     */
    @OnError
    public void onError(Session session, Throwable error){
        System.err.println("发生错误");
        error.printStackTrace();
    }


    public void sendMessage(String message) throws IOException{
        this.session.getBasicRemote().sendText(message);
        //this.session.getAsyncRemote().sendText(message);
    }

    public static synchronized int getOnlineCount() {
        return onlineCount;
    }

    public static synchronized void addOnlineCount() {
        WebSocketTest.onlineCount++;
    }

    public static synchronized void subOnlineCount() {
        WebSocketTest.onlineCount--;
    }
}

  index.jsp

<%@ page language="java" pageEncoding="UTF-8" %>
<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <title>Java后端WebSocket的Tomcat实现</title>
  <link rel="stylesheet" href="https://cdn.staticfile.org/twitter-bootstrap/3.3.7/css/bootstrap.min.css">
  <script src="https://cdn.staticfile.org/jquery/2.1.1/jquery.min.js"></script>
  <script src="https://cdn.staticfile.org/twitter-bootstrap/3.3.7/js/bootstrap.min.js"></script>

</head>
<body>
<div class="container">

  <div class="row clearfix">
    <div class="col-md-12 column">

      <div class="form-group" >
       <label  id="ts" style="color: red;"></label>
      </div>


    </div>
    <div class="col-md-12 column" id="message" style="height: 500px;overflow-y: scroll;border-bottom: 1px solid aquamarine;"  >
    </div>
  </div>

  <div class="row clearfix">

      <div class="col-md-12 column">

            <div class="form-group" >
              <textarea class="form-control" id="text" rows="4" ></textarea>
            </div>


      </div>
      <div class="col-md-12 column">
        <div class="form-group" >
          <button onclick="closeWebSocket()" class="btn btn-default">关闭WebSocket连接</button>
          <button onclick="openWebSocket()" class="btn btn-default">开启WebSocket连接</button>
          <button  onclick="send()" class="btn btn-default" style="float: right">发送消息</button>
        </div>
      </div>
  </div>
</div>



</body>

<script type="text/javascript">
  var websocket = null;


  function setWebSocketEvent(){
    //连接发生错误的回调方法
    websocket.onerror = function () {
      $("#ts").html("WebSocket连接发生错误");
    };

    //连接成功建立的回调方法
    websocket.onopen = function () {
      $("#ts").html("WebSocket连接成功");
    }

    //接收到消息的回调方法
    websocket.onmessage = function (e) {
      $('#message').append("<h4 style='text-align: right'>"  +e.data+"</h4>");
      setScrollForBottom();
    }

    //连接关闭的回调方法
    websocket.onclose = function () {
      $("#ts").html("WebSocket连接关闭");
    }


  }


  //监听窗口关闭事件，当窗口关闭时，主动去关闭websocket连接。
  window.onbeforeunload = function () {
    closeWebSocket();
  }
  function  closeWebSocket() {
    websocket.close();
  }


  function openWebSocket(){
    websocket = new  WebSocket("ws://localhost:8080/websocket");
    setWebSocketEvent();
  }

  //发送消息
  function send() {
      var message = $('#text').val();
      var s=message.split('\n')
      var smsg="";
      for(var i=0;i<s.length;i++){
        if(i+1==s.length)
          smsg=smsg+s[i];
        else
          smsg=smsg+s[i]+"<br>";
      }
      websocket.send(smsg);
  }

  function setScrollForBottom(){
    var height = document.getElementById("message").scrollHeight;
    $("#message").scrollTop(height);
    $("#message").scrollHeight;
  }

  $(function () {
    //判断当前浏览器是否支持WebSocket
    if ('WebSocket' in window) {
      websocket = new  WebSocket("ws://localhost:8080/websocket");
      setWebSocketEvent()
    }
    else {
      $("#ts").html('当前浏览器 Not support websocket');
    }

  })

</script>
</html>

效果