WebSocket + kafka实时推送数据（springboot纯后台）

逻辑：kafka订阅消费者主题 → 消费后通过webSocket推送到前端

kafka：vue_financial

webSocket：学习引用 SpringBoot2.0集成WebSocket，实现后台向前端推送信息_★【World Of Moshow 郑锴】★-CSDN博客_springboot集成websocket

项目结构：

kafka消费者service：

package com.xx.demo.service;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONException;
import com.alibaba.fastjson.JSONObject;
import kafka.consumer.ConsumerConfig;
import kafka.consumer.ConsumerIterator;
import kafka.consumer.KafkaStream;
import kafka.javaapi.consumer.ConsumerConnector;
import kafka.serializer.StringDecoder;
import kafka.utils.VerifiableProperties;
import org.springframework.stereotype.Service;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;

/**
 * Created by csn on 2020/1/7.
 */
@Service
public class KafkaComsumer {


    // 接收主题消费者
    private static ConsumerConnector backconsumer;

    // 接收主题
    public static String BACKTOPIC = "websocketTopic";

    boolean starttype = false;

    public void initkafka() {
        if (starttype) {
            return;
        }
        try {
            initBackConsumer();
            startBackConsumer();
            starttype = true;
        } catch (Exception e) {
            starttype = false;
            backconsumer.shutdown();
        }

    }

    /**
     * 初始化接收主题消费者
     */
    private static void initBackConsumer() {
        Properties props = new Properties();
        // zookeeper 集群地址
        props.put("zookeeper.connect",
                "xx.xx.xx.xx:2181,2xx.xx.xx.xx:2181,xx.xx.xx.xx:2181"); 
        // group 代表一个消费组
        props.put("group.id", "csnWebSocket-group"); //组名任意写
        // zk连接超时
        props.put("zookeeper.session.timeout.ms", "4000");
        props.put("zookeeper.sync.time.ms", "200");
        props.put("auto.commit.interval.ms", "5000");
        props.put("auto.offset.reset", "largest");
        props.put("enable.auto.commit", "false");
        // 序列化类
        props.put("serializer.class", "kafka.serializer.StringEncoder");

        ConsumerConfig config = new ConsumerConfig(props);

        backconsumer = kafka.consumer.Consumer.createJavaConsumerConnector(config);
    }

    /**
     * 开启接收主题消费者线程
     */
    public static void startBackConsumer() {

        new Thread(new Runnable() {
            @Override
            public void run() {
                Map<String, Integer> topicCountMap = new HashMap<String, Integer>();
                topicCountMap.put(BACKTOPIC, new Integer(1));
                StringDecoder keyDecoder = new StringDecoder(
                        new VerifiableProperties());
                StringDecoder valueDecoder = new StringDecoder(
                        new VerifiableProperties());
                Map<String, List<KafkaStream<String, String>>> consumerMap = backconsumer
                        .createMessageStreams(topicCountMap, keyDecoder,
                                valueDecoder);
                KafkaStream<String, String> stream = consumerMap.get(BACKTOPIC)
                        .get(0);
                ConsumerIterator<String, String> it = stream.iterator();
                String message = "";
                JSONObject obj = new JSONObject();
                while (true) {
                    while (it.hasNext()) {
                        message = it.next().message();
                        try {
                            obj = JSON.parseObject(message);
                            for (WebSocket socket: WebSocket.webSocketSet
                                 ) {
                                try {
                                    //webSocket推送消息
                                    socket.sendMessage(obj.toString());
                                } catch (Exception e) {
                                    e.printStackTrace();
                                }
                            }

                        } catch (JSONException e) {
                            continue;
                        }

                    }
                }
            }
        }, "BackThread").start();
    }

}

webSocket服务端service：

package com.xx.demo.service;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;

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

/**
 * Created by csn on 2020/1/8.
 */
@ServerEndpoint("/webSocket")
@Component
public class WebSocket {

    // 用来记录当前连接数的变量
    private static volatile int onlineCount = 0;

    // concurrent包的线程安全Set，用来存放每个客户端对应的MyWebSocket对象
    public static CopyOnWriteArraySet<WebSocket> webSocketSet = new CopyOnWriteArraySet<WebSocket>();

    //接收人
    //private String userId = "";

    // 与某个客户端的连接会话，需要通过它来与客户端进行数据收发
    private Session session;

    private static final Logger LOGGER = LoggerFactory.getLogger(WebSocket.class);

    @OnOpen
    public void onOpen(Session session) throws Exception {
        this.session = session;
        webSocketSet.add(this);
        LOGGER.info("当前在线人数为:" + webSocketSet.size());

    }

    @OnClose
    public void onClose() {
        webSocketSet.remove(this);
        LOGGER.info("Close a websocket. ");
    }

    /**
     * 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
     * */
    @OnMessage
    public void onMessage(String message, Session session) {
        LOGGER.info("Receive a message from client: " + message);
    }

    @OnError
    public void onError(Session session, Throwable error) {
        LOGGER.error("Error while websocket. ", error);
    }

    /**
     * 实现服务器主动推送
     */
    public void sendMessage(String message) throws Exception {
        if (this.session.isOpen()) {
            this.session.getBasicRemote().sendText(message);
        }
    }


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

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

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

}

webSocket配置类：

package com.xx.demo.config;

import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.server.standard.ServerEndpointExporter;

/**
 * Created by csn on 2020/1/8.
 */
@Configuration
@ConditionalOnWebApplication
public class WebSocketConfig {

    @Bean
    public ServerEndpointExporter serverEndpointExporter() {
        return new ServerEndpointExporter();
    }

    @Bean
    public MySpringConfigurator mySpringConfigurator() {
        return new MySpringConfigurator();
    }

}

Spring配置ServerEndpointConfig类：

package com.xx.demo.config;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

import javax.websocket.server.ServerEndpointConfig;

/**
 * Created by csn on 2020/1/8.
 */
public class MySpringConfigurator extends ServerEndpointConfig.Configurator implements ApplicationContextAware {

    private static volatile BeanFactory context;

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        MySpringConfigurator.context = applicationContext;
    }

    @Override
    public <T> T getEndpointInstance(Class<T> clazz) throws InstantiationException {
        return context.getBean(clazz);
    }
}

简单的前端页面（webSocket客户端）：

<!DOCTYPE html>
<html>
<head>
    <title>WebSocket示例</title>
    <meta content='width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no' name='viewport' />
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
</head>
<body>
<input id="text" type="text"/>
<button οnclick="send()">发送消息</button>
<hr/>
<button οnclick="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) {
        // 不带参数的写法
        //websocket = new WebSocket("ws://127.0.0.1:18080/webSocket");
        // 通过路径传递参数的方法（服务端采用第一种方法"@ServerEndpoint"实现）
        websocket = new WebSocket("ws://" + window.location.host + "/webSocket");
        //websocket = new WebSocket("ws://127.0.0.1:18080/webSocket/23/Lebron");
        // 通过类似GET请求方式传递参数的方法（服务端采用第二种方法"WebSocketHandler"实现）
        //websocket = new WebSocket("ws://127.0.0.1:18080/webSocket?id=23&name=Lebron");
    }
    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>

END.

亲测可用...