WebSocket

参考链接:https://segmentfault.com/a/1190000012948613

一.客户端.

　　

<%@ page language="java" pageEncoding="UTF-8" %>
<!DOCTYPE html>
<html>
<head>
    <title>Java后端WebSocket的Tomcat实现</title>
</head>
<body>
    Welcome<br/><input id="text" type="text"/>
    <button onclick="send()">发送消息</button>
    <hr/>
    <button onclick="closeWebSocket()">关闭WebSocket连接</button>
    <hr/>
    <div id="message"></div>
</body>

<script type="text/javascript">
    var websocket = null;
    //判断当前浏览器是否支持WebSocket
    if ('WebSocket' in window) {
        websocket = new WebSocket("ws://localhost:8080/testWebSocket/websocket");
    }
    else {
        alert('当前浏览器 Not support websocket')
    }

    //连接发生错误的回调方法
    websocket.onerror = function () {
        setMessageInnerHTML("WebSocket连接发生错误");
    };

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

    //接收到消息的回调方法
    websocket.onmessage = function (event) {
        setMessageInnerHTML(event.data);
    }

    //连接关闭的回调方法
    websocket.onclose = function () {
        setMessageInnerHTML("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，防止连接还没断开就关闭窗口，server端会抛异常。
    window.onbeforeunload = function () {
        closeWebSocket();
    }

    //将消息显示在网页上
    function setMessageInnerHTML(innerHTML) {
        document.getElementById('message').innerHTML += innerHTML + '<br/>';
    }

    //关闭WebSocket连接
    function closeWebSocket() {
        websocket.close();
    }

    //发送消息
    function send() {
        var message = document.getElementById('text').value;
        websocket.send(message);
    }
</script>
</html>

 

二.服务器端.

　　

package cn.guanyq.controller;

import java.io.IOException;
import java.util.concurrent.CopyOnWriteArraySet;

import javax.websocket.OnClose;
import javax.websocket.OnError;
import javax.websocket.OnMessage;
import javax.websocket.OnOpen;
import javax.websocket.Session;
import javax.websocket.server.ServerEndpoint;

//ServerEndpint注解是一个类级别注解,主要作用是将当前类定义成webSocket服务器端,注解的值用于监听url.客户端可用这个url来连接到WebSocket服务器端.
@ServerEndpoint("/websocket")
public class TestWebSocket {
    // 记录连接人数
    private static int onlineCount = 0;
    private static CopyOnWriteArraySet<TestWebSocket> socketSet = new CopyOnWriteArraySet<TestWebSocket>();
    private Session session;

    // 打开webSocket连接时调用的函数
    @OnOpen
    public void openWebSocket(Session session) {
        this.session = session;
        String id = session.getId();
        System.out.println(id);
        socketSet.add(this);
        addOnlineCount();
        System.out.println("一个客户端已经连接,当前在线人数为:" + onlineCount);
    }

    // 关闭WebSocket时调用的函数
    @OnClose
    public void closeWebSocket(Session session) {
        this.session = session;
        subOnlineCount();
        System.out.println("一个webSocket连接已经关闭,当前在线人数为:" + onlineCount);
    }

    // 接收客户端的消息之后调用的方法
    @OnMessage
    public void onMessage(String message, Session session) {
        System.out.println("服务端发送的消息为:" + message);
        // 群发消息
        try {
            for (TestWebSocket item : socketSet) {
                item.sendMessage(message);
            }
        } catch (IOException e) {

            e.printStackTrace();
        }

    }

    @OnError
    public void onError(Session session, Throwable error) {
        System.out.println("发生错误时候调用的方法");
        error.printStackTrace();
    }

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

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

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

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

 

posted @ 2018-09-27 16:55  流浪的小蛤蟆  阅读(156)  评论(0)    收藏  举报