Java WebSocket 示例（java nio websocket）

liuian 2025-07-17 20:39 62 浏览

一、环境准备

1. 依赖配置（Maven）

在 pom.xml 中添加 WebSocket 依赖： xml

<!-- Spring Boot WebSocket -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-websocket</artifactId>
</dependency>
<!-- 原生 WebSocket API（备用） -->
<dependency>
    <groupId>javax.websocket</groupId>
    <artifactId>javax.websocket-api</artifactId>
    <version>1.1</version>
</dependency>

二、服务端实现（Spring Boot）

1. WebSocket 配置类

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

@Configuration
public class WebSocketConfig {
    @Bean
    public ServerEndpointExporter serverEndpointExporter() {
        return new ServerEndpointExporter(); // 自动注册 @ServerEndpoint
    }
}

2. WebSocket 服务端类

import org.springframework.stereotype.Component;
import javax.websocket.*;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicInteger;

@Component
@ServerEndpoint("/chat/{username}")
public class ChatWebSocketServer {
    // 存储所有会话
    private static final ConcurrentHashMap<String, Session> sessions = new ConcurrentHashMap<>();
    private static final AtomicInteger onlineCount = new AtomicInteger(0);

    @OnOpen
    public void onOpen(Session session, @PathParam("username") String username) {
        sessions.put(username, session);
        onlineCount.incrementAndGet();
        System.out.println("用户 " + username + " 上线，当前在线人数：" + onlineCount);
    }

    @OnMessage
    public void onMessage(String message, Session session, @PathParam("username") String username) {
        System.out.println("收到消息：" + message);
        // 广播消息给所有用户
        broadcast(username + ": " + message);
    }

    @OnClose
    public void onClose(Session session, @PathParam("username") String username) {
        sessions.remove(username);
        onlineCount.decrementAndGet();
        System.out.println("用户 " + username + " 下线，当前在线人数：" + onlineCount);
    }

    @OnError
    public void onError(Session session, Throwable error) {
        error.printStackTrace();
    }

    // 广播消息
    private void broadcast(String message) {
        sessions.values().forEach(session -> {
            try {
                session.getAsyncRemote().sendText(message);
            } catch (IOException e) {
                e.printStackTrace();
            }
        });
    }
}

三、客户端实现

1. 浏览器端（HTML + JavaScript）

<!DOCTYPE html>
<html>
<head>
    <title>WebSocket 测试客户端</title>
</head>
<body>
    <input type="text" id="username" placeholder="用户名">
    <input type="text" id="message" placeholder="消息内容">
    <button onclick="sendMessage()">发送</button>
    <div id="output"></div>

    <script>
        const ws = new WebSocket("ws://localhost:8080/chat/用户昵称");
        ws.onmessage = function(event) {
            document.getElementById("output").innerHTML += event.data + "<br>";
        };

        function sendMessage() {
            const msg = document.getElementById("message").value;
            ws.send(msg);
        }
    </script>
</body>
</html>

2. Java 客户端（控制台交互）

import javax.websocket.*;
import java.net.URI;
import java.util.Scanner;

@ClientEndpoint
public class WebSocketClient {
    private Session session;

    public WebSocketClient(URI uri) {
        try {
            WebSocketContainer container = ContainerProvider.getWebSocketContainer();
            container.connectToServer(this, uri);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    @OnOpen
    public void onOpen(Session session) {
        this.session = session;
        System.out.println("已连接到服务器");
    }

    @OnMessage
    public void onMessage(String message) {
        System.out.println("收到消息：" + message);
    }

    public void sendMessage(String message) {
        try {
            session.getBasicRemote().sendText(message);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        WebSocketClient client = new WebSocketClient(URI.create("ws://localhost:8080/chat/TestUser"));
        Scanner scanner = new Scanner(System.in);
        while (true) {
            String msg = scanner.nextLine();
            client.sendMessage(msg);
        }
    }
}