Tomcat中WebSocket的使用

创建一个简单的Web项目，后端代码

import javax.websocket.*;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArraySet;

@ServerEndpoint("/test")
public class SendMessageWebSocket {

    private Session session;

    private static final Set<SendMessageWebSocket> connections = new CopyOnWriteArraySet<>();

    static {
        new Thread(() -> {
            while (true) {
                for (SendMessageWebSocket connection : connections) {
                    try {
                        connection.session.getBasicRemote().sendText("你好,客户端!");
                        Thread.sleep(10000L);
                        // int i = 1 / 0;
                    } catch (Exception e) {
                        System.out.println("出现异常");
                        connections.remove(connection);
                        try {
                            connection.session.close();
                        } catch (IOException ioException) {
                            ioException.printStackTrace();
                        }
                    }
                }
            }
        }).start();
    }

    @OnOpen
    public void onOpen(Session session, EndpointConfig config) {
        this.session = session;
        connections.add(this);
        System.out.println("编号[" + session.getId() + "]" + "已连接");
    }

    @OnClose
    public void onClose(Session session, CloseReason closeReason) {
        connections.remove(this);
        System.out.println("编号[" + session.getId() + "]" + "已关闭");
    }

    @OnError
    public void onError(Session session, Throwable throwable) {
        System.out.println("onError" + throwable.getMessage());
    }

    @OnMessage
    public void echoTextMessage(Session session, String msg, boolean last) {
        System.out.println("收到消息：" + msg);
    }

}

前端代码

<%@ page contentType="text/html;charset=UTF-8" %>
<html>
<head>
    <title>WebSocket推送消息</title>
</head>
<body>
<input id="message" type="text" value="编辑消息"><br>
<button onclick="sendMsg()">发送</button>
<script>
    var ws = null;
    var target = "ws://127.0.0.1:8080/websocket/test";

    function connect() {
        ws = new WebSocket(target);
        ws.onopen = function () {
            console.log("已连接至服务器");
        };
        ws.onmessage = function (event) {
            console.log("收到服务器消息:" + event.data)
        };
        ws.onclose = function () {
            console.log("服务器连接已断开");
            connect();//断开继续连接
        };
        ws.onerror = function (event) {
            alert("onerror:" + event);
        };
    }

    function sendMsg() {
        ws.send(document.getElementById('message').value);
    }

    window.onload = function () {
        connect();
    }
</script>
</body>
</html>