java搭建WebSocket的两种方式

这两种方式分别是：

1、直接使用Java EE的api进行搭建。

2、和springboot整合的WebSocket服务。

 下面分别介绍搭建方法：

一、直接使用Java EE的api进行搭建。

一共3个步骤：

1、添加依赖

<dependency>
    <groupId>javax</groupId>
    <artifactId>javaee-api</artifactId>
    <version>7.0</version>
    <scope>provided</scope>
</dependency>

 2、使用注解@ServerEndpoint

import javax.websocket.*;
import javax.websocket.server.PathParam;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.logging.Logger;

/**
 * WebSocket连接 sessionKey是url中的参数
 */
@ServerEndpoint("/websocket/{sessionKey}")
public class WebSocket {

    private static final Logger log = Logger.getLogger(WebSocket.class.getName());

    //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，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 Map<String, WebSocket> webSockets = new ConcurrentHashMap<>();

    //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;

    /**
     * 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
     * @param sessionKey url地址参数
     */
    @OnOpen
    public void onOpen(Session session, @PathParam("sessionKey") String sessionKey) {

        if (!webSockets.containsKey(sessionKey)) {
            this.session = session;
            webSockets.put(sessionKey, this);
            addOnlineCount();
            log.info("当前websocket连接数：" + onlineCount);
        }
    }

    /**
     * 连接关闭调用的方法
     *
     * @param sessionKey url地址参数
     */
    @OnClose
    public void onClose(@PathParam("sessionKey") String sessionKey) {

        if (webSockets.containsKey(sessionKey)) {
            webSockets.remove(sessionKey);
            subOnlineCount();
            log.info("当前websocket连接数：" + onlineCount);
        }
    }

    /**
     * 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) {
        log.info("来自客户端的消息:" + message);
    }

    /**
     * 发生错误时调用
     *
     * @param session 可选的参数
     * @param error   错误消息
     */
    @OnError
    public void onError(Session session, Throwable error) {
        log.info("websocket发生错误：" + error);
    }

    /**
     * 该方法没有用注解，是根据自己需要添加的方法。在自己的业务中调用，发送消息给前端。
     *
     * @param sessionKey
     * @param message    返回的结果
     * @throws IOException
     */
    public static void sendMessage(String sessionKey, String message) throws IOException {

        WebSocket webSocket = webSockets.get(sessionKey);

        if (null != webSocket) {

            log.info("websocket发送消息：" + message);

            //同步发送 发送第二条时，必须等第一条发送完成
            webSocket.session.getBasicRemote().sendText(message);

            //异步发送
            //webSocket.session.getAsyncRemote().sendText(message);
        }
    }

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

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

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

}

3、测试

在线WebSocket测试：http://coolaf.com/tool/chattest

输入地址进行测试即可，举例：ws://localhost:8080/websocket/sessionKey

补充：也可以使用java搭建客户端程序测试，测试的例程放到后面去了~~

二、和springboot整合的WebSocket服务(功能更加强大)

看下效果：

http://localhost:8080/websocket/login?username=river&password=123

 http://localhost:8080/websocket/sendToUser?username=river&info=你找我干嘛？

maven依赖如下：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-websocket</artifactId>
    <version>2.0.4.RELEASE</version>
</dependency>

1、控制类

package com.boot.river.websocket;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.socket.TextMessage;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

@Controller
@RequestMapping(value = "/websocket", method = {RequestMethod.POST, RequestMethod.GET})/*GET请求开放用于测试，最好只允许POST请求*/
public class WebSocketController {

    @Autowired
    SpringWebSocketHandler springWebSocketHandler;

    /**
     * 登录将username放入session中，然后在拦截器HandshakeInterceptor中取出
     */
    @ResponseBody
    @RequestMapping("/login")
    public String login(HttpServletRequest request, @RequestParam(value = "username") String username, @RequestParam(value = "password") String password) {
        System.out.println("登录：" + username + "：" + password);
        HttpSession session = request.getSession();
        if (null != session) {
            session.setAttribute("SESSION_USERNAME", username);
            return "success";
        } else {
            return "fail";
        }
    }

    /**
     * 指定发送
     */
    @ResponseBody
    @RequestMapping("/sendToUser")
    public String send(@RequestParam(value = "username") String username, @RequestParam(value = "info") String info) {
        springWebSocketHandler.sendMessageToUser(username, new TextMessage(info));
        System.out.println("发送至：" + username);
        return "success";
    }

    /**
     * 广播
     */
    @ResponseBody
    @RequestMapping("/broadcast")
    public String broadcast(@RequestParam(value = "info") String info) {
        springWebSocketHandler.sendMessageToUsers(new TextMessage("广播消息：" + info));
        System.out.println("广播成功");
        return "success";
    }
}

2、配置类（实现WebSocketConfigurer接口 ）

@Configuration
@EnableWebSocket
public class SpringWebSocketConfig implements WebSocketConfigurer {

    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        registry.addHandler(getSpringWebSocketHandler(), "/websocket/server")
                .addInterceptors(getInterceptor()).setAllowedOrigins("*");

        registry.addHandler(getSpringWebSocketHandler(), "/sockjs/server").setAllowedOrigins("*")
                .addInterceptors(getInterceptor()).withSockJS();
    }

    @Bean
    public SpringWebSocketHandler getSpringWebSocketHandler() {
        return new SpringWebSocketHandler();
    }

    @Bean
    public SpringWebSocketHandlerInterceptor getInterceptor() {
        return new SpringWebSocketHandlerInterceptor();
    }
}

3、处理类（实现了WebSocketHandler接口）

package com.boot.river.websocket;

import org.springframework.web.socket.CloseStatus;
import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;
import org.springframework.web.socket.handler.TextWebSocketHandler;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

public class SpringWebSocketHandler extends TextWebSocketHandler {

    /**
     * 存储用户id和其对应的session
     */
    private static final Map<String, WebSocketSession> users = new HashMap<>();

    /**
     * 用户名key值
     */
    private static final String USER_ID = "WEBSOCKET_USERID";

    /**
     * 连接建立后触发
     */
    @Override
    public void afterConnectionEstablished(WebSocketSession session) {
        System.out.println("成功建立websocket连接!");
        String userId = (String) session.getAttributes().get(USER_ID);//取出在拦截器中存储的username
        users.put(userId, session);
        System.out.println("当前线上用户数量:" + users.size());
    }

    /**
     * 关闭连接时触发
     */
    @Override
    public void afterConnectionClosed(WebSocketSession session, CloseStatus closeStatus) {
        String userId = (String) session.getAttributes().get(USER_ID);
        System.out.println("用户" + userId + "已退出！");
        users.remove(userId);
        System.out.println("剩余在线用户" + users.size());
    }

    /**
     * 接收消息
     */
    @Override
    protected void handleTextMessage(WebSocketSession session, TextMessage message) throws Exception {
        super.handleTextMessage(session, message);
        System.out.println("收到消息：" + message);
        if (message.getPayload().contains("在吗")) {
           session.sendMessage(new TextMessage("对方不在线！"));
        }
    }

    public void handleTransportError(WebSocketSession session, Throwable exception) throws Exception {
        if (session.isOpen()) {
            session.close();
        }
        System.out.println("传输出现异常，关闭websocket连接... ");
        String userId = (String) session.getAttributes().get(USER_ID);
        users.remove(userId);
    }

    public boolean supportsPartialMessages() {
        return false;
    }


    /**
     * 给某个用户发送消息
     */
    public void sendMessageToUser(String userId, TextMessage message) {
        for (String id : users.keySet()) {
            if (id.equals(userId)) {
                try {
                    if (users.get(id).isOpen()) {
                        users.get(id).sendMessage(message);
                    }
                } catch (IOException e) {
                    e.printStackTrace();
                }
                break;
            }
        }
    }

    /**
     * 给所有在线用户发送消息
     */
    public void sendMessageToUsers(TextMessage message) {
        for (String userId : users.keySet()) {
            try {
                if (users.get(userId).isOpen()) {
                    users.get(userId).sendMessage(message);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

4、拦截器（实现HandshakeInterceptor接口）

package com.boot.river.websocket;

import org.springframework.http.server.ServerHttpRequest;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.http.server.ServletServerHttpRequest;
import org.springframework.web.socket.WebSocketHandler;
import org.springframework.web.socket.server.support.HttpSessionHandshakeInterceptor;

import javax.servlet.http.HttpSession;
import java.util.Map;

public class SpringWebSocketHandlerInterceptor extends HttpSessionHandshakeInterceptor {
    @Override
    public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler,
                                   Map<String, Object> attributes) throws Exception {
        System.out.println("Before Handshake");
        if (request instanceof ServletServerHttpRequest) {
            ServletServerHttpRequest servletRequest = (ServletServerHttpRequest) request;
            HttpSession session = servletRequest.getServletRequest().getSession(false);//获取session时，如果没有则返回null
            if (session != null) {
                String userName = (String) session.getAttribute("SESSION_USERNAME");//在登录时保存的用户名
                if (userName != null) {
                    attributes.put("WEBSOCKET_USERID", userName);//放入attributes中，可以在处理器的WebSocketSession中取出
                }
            }
        }
        return super.beforeHandshake(request, response, wsHandler, attributes);
    }

    @Override
    public void afterHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler,
                               Exception ex) {
        super.afterHandshake(request, response, wsHandler, ex);
        System.out.println("after Handshake");
    }

}

参考：

https://my.oschina.net/u/3445245/blog/3003208

https://blog.csdn.net/runbat/article/details/80985944 

https://docs.spring.io/spring/docs/5.0.0.BUILD-SNAPSHOT/spring-framework-reference/html/websocket.html

 

下面分别介绍websocket的java客户端请求和js客户端请求

1、java客户端

添加依赖：

<dependency>
      <groupId>org.java-websocket</groupId>
      <artifactId>Java-WebSocket</artifactId>
      <version>1.4.0</version>
</dependency>

package com.river.websocket;

import org.java_websocket.enums.ReadyState;

import java.net.URISyntaxException;

/**
 * @author river
 * @date 2019-12-6
 */
public class Client {
    public static void main(String[] args) throws URISyntaxException, InterruptedException {
        MyWebSocketClient client = new MyWebSocketClient("ws://localhost:8080/websocket/server");
        client.connect();
        while (client.getReadyState() != ReadyState.OPEN) {
            System.out.println("连接状态：" + client.getReadyState());
            Thread.sleep(100);
        }
        client.send("测试数据！");
        client.close();
    }
}

 继承WebsocketClient

package com.river.websocket;

import org.java_websocket.client.WebSocketClient;
import org.java_websocket.handshake.ServerHandshake;

import java.net.URI;
import java.net.URISyntaxException;

public class MyWebSocketClient extends WebSocketClient {

    MyWebSocketClient(String url) throws URISyntaxException {
        super(new URI(url));
    }

    @Override
    public void onOpen(ServerHandshake shake) {
        System.out.println(shake.getHttpStatusMessage());
    }

    @Override
    public void onMessage(String paramString) {
        System.out.println(paramString);
    }

    @Override
    public void onClose(int paramInt, String paramString, boolean paramBoolean) {
        System.out.println("关闭");
    }

    @Override
    public void onError(Exception e) {
        System.out.println("发生错误");
    }
}

2、js客户端 

<!DOCTYPE html>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
    <title>websocket</title>
    <script type="text/javascript" src="http://cdn.bootcss.com/jquery/3.1.0/jquery.min.js"></script>
    <script type="text/javascript" src="http://cdn.bootcss.com/sockjs-client/1.1.1/sockjs.js"></script>
    <script type="text/javascript">
        var websocket = null;
        if ('WebSocket' in window) {
            websocket = new WebSocket("ws://localhost:8080/websocket/server");
        } else if ('MozWebSocket' in window) {
            websocket = new MozWebSocket("ws://localhost:8080/websocket/server");
        } else {
            websocket = new SockJS("http://localhost:8080/sockjs/server");
        }
        websocket.onopen = onOpen;
        websocket.onmessage = onMessage;
        websocket.onerror = onError;
        websocket.onclose = onClose;

        function onOpen(event) {
            alert(event.type);
        }

        function onMessage(messageEvent) {
            alert(messageEvent.data);
        }

        function onError(event) {
        }

        function onClose(closeEvent) {
            alert(closeEvent.reason);
        }

        function doSendUser() {
            if (websocket.readyState === websocket.OPEN) {
                var msg = document.getElementById("inputMsg").value;
                websocket.send(msg);//发送消息
                alert("发送成功!");
            } else {
                alert("连接失败!");
            }
        }

        window.close = function () {
            websocket.onclose();
        };
        function websocketClose() {
            websocket.close();
            alert("连接关闭");
        }
    </script>
</head>
<body>

请输入：<input id="inputMsg" name="inputMsg"/>
<button οnclick="doSendUser();">发送</button>
<button οnclick="websocketClose();">关闭连接</button>
</body>
</html>

补充：登录方式除了在Controller中处理，还可以在Websocket中接收到的消息进行登录处理。

觉得有用的老铁赞一下呗！