社区首页 >专栏 >Kafka+WebSocket=实时数据大屏

Kafka+WebSocket=实时数据大屏

857技术社区

发布于 2022-05-17 07:04:21

3.1K02

代码可运行

文章被收录于专栏：857-Bigdata857-Bigdata

运行总次数：2

代码可运行

一、WebSocket简介

WebSocket网上很多教程，这里不详细描述。简单来说：WebSocket协议是基于TCP的一种新的网络协议。它实现了浏览器与服务器全双工(full-duplex)通信——允许服务器主动发送信息给客户端。

二、SpringBoot实现WebSocket

maven依赖如下

        <!--Web项目必须加上-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <!-- springboot websocket -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-websocket</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <!--Kafka依赖包-->
        <dependency>
            <groupId>org.apache.kafka</groupId>
            <artifactId>kafka_2.12</artifactId>
            <version>2.3.0</version>
        </dependency>

编写以下代码启用WebSocket

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

/**
 * @author 李奇峰
 * 2019年5月10日11:08:22
 * websocket的配置
 */
@Configuration
public class WebSocketStompConfig{
    @Bean
    public ServerEndpointExporter serverEndpointExporter()
    {
        return new ServerEndpointExporter();
    }
}

编写WebSockerServer类

此类中的session连接会话全都保存在了一个静态的Map对象websocketClients 中，在开启连接时将连接会话根据连接名保存在此Map中，方便后续Kafka发送消息时进行全局调用。

package com.fsl.springbootwebsocket.config;

import com.alibaba.fastjson.JSONObject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;

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;

/**
 * @author 2019年5月10日11:08:16
 */
@Component
@ServerEndpoint("/websocket/{socketname}")
public class WebSocketServer {
    private Logger logger = LoggerFactory.getLogger(this.getClass());
    /**
     * 以通道名称为key，连接会话为对象保存起来
     */
    public static Map<String, Session> websocketClients = new ConcurrentHashMap<String, Session>();
    /**
     * 会话
     */
    private Session session;
    /**
     * 通道名称
     */
    private String socketname;

    /**
     * 发送消息到指定连接
     * @param socketname 连接名
     * @param jsonString 消息
     */
    public static void sendMessage(String socketname,String jsonString){
        Session nowsession = websocketClients.get(socketname);
        if(nowsession!=null){
            try {
                nowsession.getBasicRemote().sendText(jsonString);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    @OnOpen
    public void onOpen(@PathParam("socketname") String socketname, Session session)
    {

        this.socketname = socketname;
        this.session = session;
        if(websocketClients.get(socketname)==null){
            websocketClients.put(socketname, session);
            System.out.println("当前socket通道"+socketname+"已加入连接");
        }
    }

    @OnError
    public void onError(Session session, Throwable error) {
        logger.info("服务端发生了错误"+error.getMessage());
    }
    /**
     * 连接关闭
     */
    @OnClose
    public void onClose()
    {
        websocketClients.remove(socketname);
        System.out.println("当前socket通道"+socketname+"已退出连接");

    }

    /**
     * 收到客户端的消息
     *
     * @param message 消息
     * @param session 会话
     */
    @OnMessage
    public void onMessage(String message, Session session){
        System.out.println("当前收到了消息："+message);
        session.getAsyncRemote().sendText("来自服务器："+this.socketname+"你的消息我收到啦");
    };

    /**
     * 向所有连接主动推送消息
     * @param jsonObject 消息体
     * @throws IOException
     */
    public void sendMessageAll(JSONObject jsonObject) throws IOException {
        for (Session item : websocketClients.values()) {
            item.getAsyncRemote().sendText(jsonObject.toJSONString());
        }
    }

}

三、Kafka实现

此消费者在消费消息时，会调用WebSockerServer类中的sendMessage函数，将消息发送到websocket中此类继承了Thread类，因为Kafka运行时会一直监听通道中的消息，为了避免进程阻塞，我们将其作为单独的线程来运行

import org.apache.kafka.clients.consumer.Consumer;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import java.util.*;

import static com.fsl.springbootwebsocket.config.WebSocketServer.sendMessage;

public class SocketConsumer extends Thread {

    @Override
    public void run(){
        Properties prop = new Properties();
        System.out.println("启动kafka消费者....");
        prop.put("bootstrap.servers","cdh3:9092");
        prop.put("group.id","socket");
        prop.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
        prop.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
//如果是之前存在的group.id
        Consumer consumer = new KafkaConsumer(prop);
        consumer.subscribe(Arrays.asList("zeek_test"));
        while (true) {
            ConsumerRecords<String, String> c = consumer.poll(100);
            for(ConsumerRecord<String, String> c1: c) {
                System.out.println(c1.value());
                sendMessage("socket",c1.value());
            }
        }
    }
}

在此类在SpringBoot注册并启动

import org.springframework.stereotype.Component;

@Component
public class ConsumerLinster  {
    public ConsumerLinster(){
        System.out.println("启用Kafka监听器");
        SocketConsumer socketConsumer = new SocketConsumer();
        socketConsumer.start();
        System.out.println("Kafka监听器启用成功");
    }
}