# 利刃出鞘_Tomcat 核心原理解析（十一）-- Tomcat 附加功能 WebSocket -- 3

利刃出鞘_Tomcat 核心原理解析（十一）-- Tomcat 附加功能 WebSocket – 3

一、Tomcat专题 - WebSocket - 案例 - OnMessage分析

1、WebSocket DEMO 案例 实现流程分析：OnMessage 分析

2、在项目 dzs168_chat_room 中，在 websocket 类 ChatSocket.java 中，

创建 public void onMessage(String message, Session session) {…} 方法。分析流程。

    //{"fromName":"Deng","toName":"HEIMA","content":"约会呀"}
    @OnMessage
    public  void onMessage(String message, Session session) {
       
        //1. 获取客户端的信息内容, 并解析
       
        //2. 判定是否有接收人
        
        //3. 如果接收人是否是广播(all), 如果是, 则说明发送广播消息
       
	    //4. 不是all , 则给指定的用户推送消息
       
    }

二、Tomcat专题 - WebSocket - 案例 - OnMessage功能实现

1、在项目 dzs168_chat_room 中，在 websocket 类 ChatSocket.java 中，

完成 onMessage(String message, Session session) {…} 方法代码编写。

    //{"fromName":"Deng","toName":"HEIMA","content":"约会呀"}
    @OnMessage
    public  void onMessage(String message, Session session) throws IOException {
        System.out.println("onMessage : name = " + httpSession.getAttribute("username")+ ", message=" + message );
        //1. 获取客户端的信息内容, 并解析
        Map<String,String> messageMap = JSON.parseObject(message, Map.class);
        String fromName = messageMap.get("fromName");
        String toName = messageMap.get("toName");
        String content = messageMap.get("content");

        //2. 判定是否有接收人
        if(toName == null || toName.isEmpty()){
            return;
        }

        //3. 如果接收人是否是广播(all), 如果是, 则说明发送广播消息
        String messageContent = MessageUtil.getContent(MessageUtil.TYPE_MESSAGE, fromName, toName, content);
        System.out.println("服务端给客户端发送消息, 消息内容: " + messageContent);
        if("all".equals(toName)){
            //3.1 组装消息内容
            broadcastAllUsers(messageContent);
        }else{//4. 不是all , 则给指定的用户推送消息
            singlePushMessage(messageContent, fromName,toName);
        }

    }

2、在项目 dzs168_chat_room 中，在 websocket 类 ChatSocket.java 中，

创建 //给指定用户推送消息 private void singlePushMessage(String content, String fromName, String toName) throws IOException {…} 方法，并完成代码编写。

    //给指定用户推送消息
    private void singlePushMessage(String content, String fromName, String toName) throws IOException {
        boolean isOnline = false;
        //1. 判定当然接收人是否在线
        for (HttpSession hsession : onlineUsers.keySet()) {
            if(toName.equals(hsession.getAttribute("username"))){
                isOnline = true;
            }
        }

        //2. 如果存在, 发送消息
        if(isOnline){
            for (HttpSession hsession : onlineUsers.keySet()) {
                if (hsession.getAttribute("username").equals(fromName) || hsession.getAttribute("username").equals(toName)){
                    onlineUsers.get(hsession).session.getBasicRemote().sendText(content);
                }
            }
        }

    }

3、项目 dzs168_chat_room 中，websocket 类 ChatSocket.java 代码。

/**
 *   project_tomcat\dzs168_chat_room\src\djh\it\websocket\ChatSocket.java
 *
 *   2024-9-2 创建 websocket 类 ChatSocket.java
 */

package djh.it.websocket;

import djh.it.utils.MessageUtil;
import com.alibaba.fastjson.JSON;

import javax.servlet.http.HttpSession;
import javax.websocket.*;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

@ServerEndpoint(value = "/websocket",configurator = GetHttpSessionConfigurator.class )
public class ChatSocket {

    private  Session session;
    private  HttpSession httpSession;

    //保存当前系统中登录的用户的HttpSession信息, 及对应的Endpoint实例信息
    private static Map<HttpSession , ChatSocket> onlineUsers = new HashMap<HttpSession, ChatSocket>();
    private static int onlineCount = 0;

    @OnOpen
    public void onOpen(Session session, EndpointConfig config){

        //1. 记录webSocket的会话信息对象Session
        this.session = session;

        //2. 获取当前登录用户HttpSession信息.
        HttpSession httpSession = (HttpSession) config.getUserProperties().get(HttpSession.class.getName());
        this.httpSession = httpSession;

        System.out.println("当前登录用户 : " + httpSession.getAttribute("username") +", Endpoint : " +hashCode());

        //3. 记录当前登录用户信息, 及对应的Endpoint实例
        if (httpSession.getAttribute("username") != null){
            onlineUsers.put(httpSession,this);
        }

        //4. 获取当前所有登录用户 --------> DZS168,dzs,TOM...
        String names = getNames();

        //5. 组装消息 ---> {"data":"dzs168,Deng,study","toName":"","fromName":"","type":"user"}
        String message = MessageUtil.getContent(MessageUtil.TYPE_USER, "", "", names);

        //6. 通过广播的形式发送消息
        //session.getBasicRemote().sendText("");
        broadcastAllUsers(message);

        //7. 记录当前用户登录数 .
        incrCount();

    }

    //{"fromName":"Deng","toName":"HEIMA","content":"约会呀"}
    @OnMessage
    public  void onMessage(String message, Session session) throws IOException {
        System.out.println("onMessage : name = " + httpSession.getAttribute("username")+ ", message=" + message );
        //1. 获取客户端的信息内容, 并解析
        Map<String,String> messageMap = JSON.parseObject(message, Map.class);
        String fromName = messageMap.get("fromName");
        String toName = messageMap.get("toName");
        String content = messageMap.get("content");

        //2. 判定是否有接收人
        if(toName == null || toName.isEmpty()){
            return;
        }

        //3. 如果接收人是否是广播(all), 如果是, 则说明发送广播消息
        String messageContent = MessageUtil.getContent(MessageUtil.TYPE_MESSAGE, fromName, toName, content);
        System.out.println("服务端给客户端发送消息, 消息内容: " + messageContent);
        if("all".equals(toName)){
            //3.1 组装消息内容
            broadcastAllUsers(messageContent);
        }else{//4. 不是all , 则给指定的用户推送消息
            singlePushMessage(messageContent, fromName,toName);
        }

    }

    //给指定用户推送消息
    private void singlePushMessage(String content, String fromName, String toName) throws IOException {
        boolean isOnline = false;
        //1. 判定当然接收人是否在线
        for (HttpSession hsession : onlineUsers.keySet()) {
            if(toName.equals(hsession.getAttribute("username"))){
                isOnline = true;
            }
        }

        //2. 如果存在, 发送消息
        if(isOnline){
            for (HttpSession hsession : onlineUsers.keySet()) {
                if (hsession.getAttribute("username").equals(fromName) || hsession.getAttribute("username").equals(toName)){
                    onlineUsers.get(hsession).session.getBasicRemote().sendText(content);
                }
            }
        }

    }


    // 发送广播消息
    private void broadcastAllUsers(String message) {

        for (HttpSession hsession : onlineUsers.keySet()) {
            try {
                onlineUsers.get(hsession).session.getBasicRemote().sendText(message);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

    }

    //获取所有的在线用户
    private String getNames() {
        String names = "";
        if(onlineUsers.size()>0){
            for (HttpSession hsession : onlineUsers.keySet()) {
                String username = (String) hsession.getAttribute("username");
                names += username+",";
            }
        }
        return names.substring(0,names.length()-1);
    }

    public int getOnlineCount(){
        return onlineCount;
    }

    public synchronized void incrCount(){
        onlineCount ++;
    }

    public synchronized void decrCount(){
        onlineCount --;
    }

}

三、Tomcat专题 - WebSocket - 案例 - OnMessage功能测试

1、项目 dzs168_chat_room 中，前端源码 chat.jsp 页面。

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html lang="en">
<head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="format-detection" content="telephone=no">
    <meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=0, minimum-scale=1.0, maximum-scale=1.0">
    <meta name="mobile-web-app-capable" content="yes">
    <meta name="apple-mobile-web-app-capable" content="yes">
    <meta content="yes" name="apple-mobile-web-app-capable">
    <meta content="yes" name="apple-touch-fullscreen">
    <meta name="full-screen" content="yes">
    <meta content="default" name="apple-mobile-web-app-status-bar-style">
    <meta name="screen-orientation" content="portrait">
    <meta name="browsermode" content="application">
    <meta name="msapplication-tap-highlight" content="no">
    <meta name="x5-orientation" content="portrait">
    <meta name="x5-fullscreen" content="true">
    <meta name="x5-page-mode" content="app">
    <base target="_blank">
    <title>段子手168-聊天室</title>
    <link href="css/bootstrap.min.css" rel="stylesheet" type="text/css"/>
    <link rel="stylesheet" href="css/chat.css">
    <script src="js/jquery-1.9.1.min.js"></script>

    <script type="text/javascript">
        <%
            String name = session.getAttribute("username")+"";
        %>
        var self = "<%= name %>";
    </script>
    <script type="text/javascript" src="js/ws.js"></script>
</head>

<body  onl oad="startWebSocket(self);">

<img style="width:100%;height:100%" src="img/chat_bg.jpg">

<div class="abs cover contaniner">
    <div class="abs cover pnl">
        <div class="top pnl-head" style="padding: 20px ; color: white;" id="userName"></div>
        <div class="abs cover pnl-body" id="pnlBody">
            <div class="abs cover pnl-left">
                <div class="abs cover pnl-msgs scroll" id="show">
                    <div class="pnl-list" id="hists"><!-- 历史消息 --></div>
                    <div class="pnl-list" id="msgs">
                        <!-- 消息这展示区域 -->
                    </div>
                </div>

                <div class="abs bottom pnl-text">
                    <div class="abs cover pnl-input">
                        <textarea class="scroll" id="context_text" onkeydown="sendMessage(self)" wrap="hard" placeholder="在此输入文字信息..."></textarea>
                        <div class="abs atcom-pnl scroll hide" id="atcomPnl">
                            <ul class="atcom" id="atcom"></ul>
                        </div>
                    </div>

                    <div class="abs br pnl-btn" id="submit" style="background-color: rgb(32, 196, 202); color: rgb(255, 255, 255);" onclick="sendMsg(self)">
                        发送
                    </div>
                    <div class="pnl-support" id="copyright"><a href="http://www.itcast.cn">段子手168,版本所有</a></div>
                </div>
            </div>

            <div class="abs right pnl-right">
                <div class="slider-container hide"></div>
                <div class="pnl-right-content">
                    <div class="pnl-tabs">
                        <div class="tab-btn active" id="hot-tab">好友列表</div>
                    </div>
                    <div class="pnl-hot">
                        <ul class="rel-list unselect" id="userlist">
                        </ul>
                    </div>

                </div>

                <div class="pnl-right-content">
                    <div class="pnl-tabs">
                        <div class="tab-btn active">系统广播</div>
                    </div>
                    <div class="pnl-hot">
                        <ul class="rel-list unselect" id="broadcastList">
                        </ul>
                    </div>
                </div>

            </div>
        </div>
    </div>
</div>
</body>
</html>
<!-- project_tomcat\dzs168_chat_room\web\chat.jsp -->

2、项目 dzs168_chat_room 中，前端源码 login.jsp 页面。

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html lang="en">
<head>
    <title>段子手聊天室——登录</title>
    <meta name="viewport" content="width=device-width, initial-scale=1"/>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <meta name="keywords"
          content="Transparent Sign In Form Responsive Widget,Login form widgets, Sign up Web forms , Login signup Responsive web form,Flat Pricing table,Flat Drop downs,Registration Forms,News letter Forms,Elements"/>
    <script type="application/x-javascript">
        addEventListener("load", function () {
            setTimeout(hideURLbar, 0);
        }, false);

        function hideURLbar() {
            window.scrollTo(0, 1);
        }
    </script>

    <script src="js/jquery-1.9.1.min.js"></script>
    <link rel="icon" href="img/chat.ico" type="image/x-icon"/>
    <link rel="stylesheet" href="css/font-awesome.css"/> <!-- Font-Awesome-Icons-CSS -->
    <link rel="stylesheet" href="css/login.css" type="text/css" media="all"/> <!-- Style-CSS -->
</head>

<body class="background">
<div class="header-w3l">
    <h1>段子手168聊天室</h1>
</div>
<div class="main-content-agile">
    <div class="sub-main-w3">
        <h2>登录</h2>
        <form>

            <div class="icon1">
                <input placeholder="用户名" id="username" type="text"/>
            </div>

            <div class="icon2">
                <input placeholder="密码" id="password" type="password"/>
            </div>

            <div class="clear"></div>
            <input type="button" value="登录" onclick="login()"/>
        </form>
    </div>
</div>
<div class="footer">
    <p>段子手168 版权所有Copyright 2024-9-1  All Rights Reserved </p>
</div>
</body>
<script type="text/javascript">
    function login() {
        $.ajax({
            type: 'POST',
            url: '/login',
            dataType: 'json',
            data: {
                username: $("#username").val(),
                password: $("#password").val()
            },
            success: function (data) {
                if (data.success) {
                    window.location.href = "chat.jsp";
                } else {
                    alert(data.message);
                }
            }
        });
    }

</script>
</html>
<!-- project_tomcat\dzs168_chat_room\web\login.jsp -->

3、项目 dzs168_chat_room 中，//定义全局的webSocket对象 ws.js 源码。

…\project_tomcat\dzs168_chat_room\web\js\ws.js

//定义全局的webSocket对象
var ws = null;

function startWebSocket(self) {
    //构建WebSocket对象
    if ('WebSocket' in window) {
        ws = new WebSocket("ws://localhost:8080/websocket");
    } else if ('MozWebSocket' in window) {
        ws = new MozWebSocket("ws://localhost:8080/websocket");
    } else {
        alert("not support");
    }

    //监听消息， 有消息传递， 会触发此方法
    ws.onmessage = function (evt) {
        var _data = evt.data;
        console.log(">> : " + _data);

        var o = JSON.parse(_data);

        if (o.type == 'message') { //如果后端, 响应的是消息, 在页面展示
            setMessageInnerHTML(o, self);
        } else if (o.type == 'user') { // 如果服务端响应的是用户列表, 在界面展示用户列表
            var userArry = o.data.split(',');
            $("#userlist").empty();
            $("#userlist").append('<li class="rel-item"><input type="radio" name="toUser" value="all">广播</input></li>');
            $.each(userArry, function (n, value) {
                if (value != self && value != 'admin') {
                    $("#userlist").append('<li class="rel-item"><input type="radio"  name="toUser" value="'+value+'">'+value+'</input></li>');

                    $("#broadcastList").append('<li class="rel-item">您的好友 '+value+' 已上线</li>');
                }
            });
        }
    };

    //关闭链接时触发
    ws.onclose = function (evt) {
        $('#userName').html("用户： "+ self +"<span style='float: right;color: red'>离线</span>");
    };

    //打开时触发
    ws.onopen = function (evt) {
        $('#userName').html("用户： "+ self +"<span style='float: right;color: green'>在线</span>");
    };
}

function setMessageInnerHTML(msg, self) {

    //根据后台响应的数据, 判定是展示在左侧还是右侧.
    var str = "";

    if(msg.toName == 'all'){
        $("#broadcastList").append('<li class="rel-item"> 系统广播消息： '+msg.data+' </li>');
    }else if (msg.fromName == self) {
        str = "<div class=\"msg guest\"><div class=\"msg-right\"><div class=\"msg-host headDefault\"></div><div class=\"msg-ball\" title=\"今天 17:52:06\">" + msg.data + "</div></div></div>"
    } else if(msg.toName == self){
        str = "<div class=\"msg robot\"><div class=\"msg-left\" worker=\"" + msg.fromName + "\"><div class=\"msg-host photo\" style=\"background-image: url(../img/avatar/Member002.jpg)\"></div><div class=\"msg-ball\" title=\"今天 17:52:06\">" + msg.data + "</div></div></div>";
    }

    //获取到现有的内容, 追加新的消息内容
    var msgs = document.getElementById("msgs");
    msgs.innerHTML = msgs.innerHTML + str;


    //判定消息来源的用户 , 勾选对应的好友信息
    var a = $('input[name="toUser"]');
    for(var i=0 ; i < a.length ; i++){
        if(a[i].value == msg.fromName){
            console.log(a[i]);
            a[i].checked='checked';
        }
    }
}

// 组装消息, 发送消息
function sendMsg(self) {
    var content = $("#context_text").val();

    if(!content){
        alert('请输入消息内容');
        return ;
    }

    var message = {};
    message.fromName = self;
    message.toName = $('input:radio:checked').val();  //根据界面勾选的用户, 来决定消息发送给谁
    message.content = content; //获取输入文本框中输入的内容
    var msg = JSON.stringify(message);

    console.log(" msg: "+msg);

    ws.send(msg);//发送消息
    $("#context_text").val(''); //将输入框内容置为空
}

function sendMessage(self){
    if(event.keyCode == 13){
        sendMsg(self);
    }
}

4、运行 tomcat 服务，进行测试。

5、多个 浏览器地址栏输入：localhost:8080/ 登录几个不同用户，进行测试。

四、Tomcat专题 - WebSocket - 案例 - OnClose及OnError介绍

1、在项目 dzs168_chat_room 中，在 websocket 类 ChatSocket.java 中，

创建 public void onClose(Session session, CloseReason closeReason){…} 方法。

    @OnClose
    public void onClose(Session session, CloseReason closeReason){
        decrCount();
        System.out.println("客户端关闭了一个连接 , 当前在线人数 : " + getOnlineCount());
    }

2、在项目 dzs168_chat_room 中，在 websocket 类 ChatSocket.java 中，

创建 public void one rror(Session session, Throwable throwable){…} 方法。

    @OnError
    public void one rror(Session session, Throwable throwable){
        throwable.printStackTrace();
        System.out.println("服务异常");
    }

3、项目 dzs168_chat_room 中，websocket 类 ChatSocket.java 代码。

/**
 *   project_tomcat\dzs168_chat_room\src\djh\it\websocket\ChatSocket.java
 *
 *   2024-9-2 创建 websocket 类 ChatSocket.java
 */

package djh.it.websocket;

import djh.it.utils.MessageUtil;
import com.alibaba.fastjson.JSON;

import javax.servlet.http.HttpSession;
import javax.websocket.*;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

@ServerEndpoint(value = "/websocket",configurator = GetHttpSessionConfigurator.class )
public class ChatSocket {

    private  Session session;
    private  HttpSession httpSession;

    //保存当前系统中登录的用户的HttpSession信息, 及对应的Endpoint实例信息
    private static Map<HttpSession , ChatSocket> onlineUsers = new HashMap<HttpSession, ChatSocket>();
    private static int onlineCount = 0;

    @OnOpen
    public void onOpen(Session session, EndpointConfig config){

        //1. 记录webSocket的会话信息对象Session
        this.session = session;

        //2. 获取当前登录用户HttpSession信息.
        HttpSession httpSession = (HttpSession) config.getUserProperties().get(HttpSession.class.getName());
        this.httpSession = httpSession;

        System.out.println("当前登录用户 : " + httpSession.getAttribute("username") +", Endpoint : " +hashCode());

        //3. 记录当前登录用户信息, 及对应的Endpoint实例
        if (httpSession.getAttribute("username") != null){
            onlineUsers.put(httpSession,this);
        }

        //4. 获取当前所有登录用户 --------> DZS168,dzs,TOM...
        String names = getNames();

        //5. 组装消息 ---> {"data":"dzs168,Deng,study","toName":"","fromName":"","type":"user"}
        String message = MessageUtil.getContent(MessageUtil.TYPE_USER, "", "", names);

        //6. 通过广播的形式发送消息
        //session.getBasicRemote().sendText("");
        broadcastAllUsers(message);

        //7. 记录当前用户登录数 .
        incrCount();

    }

    //{"fromName":"Deng","toName":"HEIMA","content":"约会呀"}
    @OnMessage
    public  void onMessage(String message, Session session) throws IOException {
        System.out.println("onMessage : name = " + httpSession.getAttribute("username")+ ", message=" + message );
        //1. 获取客户端的信息内容, 并解析
        Map<String,String> messageMap = JSON.parseObject(message, Map.class);
        String fromName = messageMap.get("fromName");
        String toName = messageMap.get("toName");
        String content = messageMap.get("content");

        //2. 判定是否有接收人
        if(toName == null || toName.isEmpty()){
            return;
        }

        //3. 如果接收人是否是广播(all), 如果是, 则说明发送广播消息
        String messageContent = MessageUtil.getContent(MessageUtil.TYPE_MESSAGE, fromName, toName, content);
        System.out.println("服务端给客户端发送消息, 消息内容: " + messageContent);
        if("all".equals(toName)){
            //3.1 组装消息内容
            broadcastAllUsers(messageContent);
        }else{//4. 不是all , 则给指定的用户推送消息
            singlePushMessage(messageContent, fromName,toName);
        }

    }

    //给指定用户推送消息
    private void singlePushMessage(String content, String fromName, String toName) throws IOException {
        boolean isOnline = false;
        //1. 判定当然接收人是否在线
        for (HttpSession hsession : onlineUsers.keySet()) {
            if(toName.equals(hsession.getAttribute("username"))){
                isOnline = true;
            }
        }

        //2. 如果存在, 发送消息
        if(isOnline){
            for (HttpSession hsession : onlineUsers.keySet()) {
                if (hsession.getAttribute("username").equals(fromName) || hsession.getAttribute("username").equals(toName)){
                    onlineUsers.get(hsession).session.getBasicRemote().sendText(content);
                }
            }
        }

    }


    // 发送广播消息
    private void broadcastAllUsers(String message) {

        for (HttpSession hsession : onlineUsers.keySet()) {
            try {
                onlineUsers.get(hsession).session.getBasicRemote().sendText(message);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

    }

    //获取所有的在线用户
    private String getNames() {
        String names = "";
        if(onlineUsers.size()>0){
            for (HttpSession hsession : onlineUsers.keySet()) {
                String username = (String) hsession.getAttribute("username");
                names += username+",";
            }
        }
        return names.substring(0,names.length()-1);
    }


    @OnClose
    public void onClose(Session session, CloseReason closeReason){
        decrCount();
        System.out.println("客户端关闭了一个连接 , 当前在线人数 : " + getOnlineCount());
    }


    @OnError
    public void one rror(Session session, Throwable throwable){
        throwable.printStackTrace();
        System.out.println("服务异常");
    }


    public int getOnlineCount(){
        return onlineCount;
    }

    public synchronized void incrCount(){
        onlineCount ++;
    }

    public synchronized void decrCount(){
        onlineCount --;
    }

}

4、重新运行 tomcat 服务，多个 浏览器地址栏输入：localhost:8080/ 登录几个不同用户，再退出登录，进行测试。

上一节关联链接请点击

# 利刃出鞘_Tomcat 核心原理解析（十一）-- Tomcat 附加功能-- WebSocket – 1

# 利刃出鞘_Tomcat 核心原理解析（十一）-- Tomcat 附加功能-- WebSocket – 2