結合redis訂閱和發佈消息，解決websocket多節點問題

                         結合redis訂閱和發佈消息，解決websocket多節點問題

單節點和多節點下，websocket會出現什麼問題呢？看如下兩個對比圖：

這時候你會發現有部分連接在ws node2節點上用戶收不到消息推送。而且websocket的session是無法共享的，加上session是有序無法存入到redis緩存中。

瞭解大概內容後，直接進入到代碼模塊

1.相關依賴

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

        <dependency>
            <groupId>org.apache.tomcat.embed</groupId>
            <artifactId>tomcat-embed-websocket</artifactId>
            <version>8.5.23</version>
        </dependency>

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

        <dependency>
            <groupId>redis.clients</groupId>
            <artifactId>jedis</artifactId>
            <version>2.9.0</version>
        </dependency>

2.在RedisConfig加入消息監聽容器

@Configuration
public class RedisConfig{

    /**
     * 使CacheComponent的redisTemplate組件的key使用StringRedisSerializer而非默認的JdkSerializationRedisSerializer
     * 避免key出現字節碼的情況
     * @param factory redis鏈接
     * @return RedisTemplate
     */
    @Bean
    public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory factory) {
        RedisTemplate<String, Object> redisTemplate = new RedisTemplate<>();
        redisTemplate.setConnectionFactory(factory);
        RedisSerializer redisSerializer = new StringRedisSerializer();
        Jackson2JsonRedisSerializer jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer(Object.class);
        //key使用StringRedisSerializer序列化
        redisTemplate.setKeySerializer(redisSerializer);
        //value使用jackson2JsonRedisSerializer序列化
        redisTemplate.setValueSerializer(jackson2JsonRedisSerializer);
        return redisTemplate;
    }

    /**
     * 創建Redis消息監聽者容器
     * @param factory
     * @return
     */
    @Bean("redisMessageListenerContainer")
    public RedisMessageListenerContainer redisMessageListenerContainer(RedisConnectionFactory factory){
        RedisMessageListenerContainer container = new RedisMessageListenerContainer();
        container.setConnectionFactory(factory);
        return container;
    }
}

3.新建消息訂閱監聽類

import com.opp.util.CommonUtil;
import org.springframework.data.redis.connection.Message;
import org.springframework.data.redis.connection.MessageListener;
import org.springframework.stereotype.Component;

import javax.websocket.Session;
import java.io.IOException;

/**
 * @author: huangnenghuan
 * @create: 2019/12/03
 * @description: 創建消息訂閱監聽者類
 **/
@Component
public class RedisMessageListener implements MessageListener {

    private org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(RedisMessageListener.class);

    /**
     * websocket客戶端連接會話對象
     */
    private Session session;

    public Session getSession() {
        return session;
    }

    public void setSession(Session session) {
        this.session = session;
    }

    @Override
    public void onMessage(Message message, byte[] bytes) {
        String msg = new String(message.getBody()).replace("\"", "");
        if(CommonUtil.isNotNull(session) && session.isOpen()){
            try {
                session.getBasicRemote().sendText(msg);
            }catch (IOException e){
                logger.error("RedisSubListener消息訂閱監聽異常：" + e.getMessage());
            }
        }
    }
}

4.對websocket進行修改

import com.opp.listener.RedisMessageListener;
import com.opp.util.CommonUtil;
import com.opp.util.SpringUtils;
import org.slf4j.LoggerFactory;
import org.springframework.data.redis.listener.PatternTopic;
import org.springframework.data.redis.listener.RedisMessageListenerContainer;
import org.springframework.web.bind.annotation.RestController;

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

/**
 * @author: huangnenghuan
 * @create: 2019/11/25
 * @description: websocket
 **/
@RestController
@ServerEndpoint("/webSocket/{id}")
public class WebSocketController {

    private org.slf4j.Logger logger = LoggerFactory.getLogger(WebSocketController.class);

    /**
     * 用來記錄當前連接數的變量
     */
    private static volatile int onlineCount = 0;

    public static ConcurrentHashMap<String, WebSocketController> webSocketSet = new ConcurrentHashMap<>();

    /**
     * 與某個客戶端的連接會話，需要通過它來與客戶端進行數據收發
     */
    private Session session;

    /**
     * 用來引入剛纔在webcoketConfig注入的類
     */
    private RedisMessageListenerContainer container = SpringUtils.getBean("redisMessageListenerContainer");

    /**
     * 自定義的消息發送器
     */
    private RedisMessageListener listener;

    /**
     * 連接建立成功調用的方法
     * @param id
     * @param session
     * @throws Exception
     */
    @OnOpen
    public void onOpen(@PathParam("id") String id, Session session) throws Exception {
        try {
            this.session = session;
            webSocketSet.put(id, this);
            //在線人數增加1
            addOnlineCount();
            sendMessage("連接成功");
            listener = new RedisMessageListener();
            //放入session
            listener.setSession(session);
            container.addMessageListener(listener, new PatternTopic("liveBroadcast"));
        } catch (IOException e) {
            logger.error("websocket IO異常");
        }
    }

    /**
     * 連接關閉調用方法
     */
    @OnClose
    public void onClose() {
        webSocketSet.remove(this);
        subOnlineCount();
        logger.info("websocket有一連接關閉");
        container.removeMessageListener(listener);
    }

    /**
     * 收到客戶端消息後調用方法
     * @param message
     * @param session
     */
    @OnMessage
    public void onMessage(String message, Session session) throws Exception{
        if (session.isOpen()) {
            session.getBasicRemote().sendText(message);
        }
    }

    /**
     * @param session
     * @param error
     */
    @OnError
    public void onError(Session session, Throwable error) {
        logger.error("websocket 發生異常", error);
    }

    /**
     * 向客戶端發送消息推送
     * @param message
     * @throws Exception
     */
    public void sendMessage(String message) throws Exception {
        if (this.session.isOpen()) {
            this.session.getBasicRemote().sendText(message);
        }
    }

    /**
     * 發送信息給指定ID用戶，如果用戶不在線則返回
     * @param message
     * @param sendUserId
     * @throws IOException
     */
    public void sendUserMessage(String message,String sendUserId) throws Exception {
        if(CommonUtil.isNotNull(webSocketSet.get(sendUserId))){
            webSocketSet.get(sendUserId).sendMessage(message);
        }else{
            logger.info("當前用戶不在線：" + sendUserId);
        }
    }

    /**
     * 推送信息給所有用戶
     * @param message
     * @throws IOException
     */
    public void sendAllMessage(String message) throws IOException {
        for(String key : webSocketSet.keySet()){
            try {
                webSocketSet.get(key).sendMessage(message);
            }catch (Exception e){
                logger.info("推送信息給所有用戶異常：" + e.getMessage());
            }
        }
    }

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

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

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

/**
 * @author: huangnenghuan
 * @create: 2019/12/03
 * @description:
 **/
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.stereotype.Component;

//定義爲final類
@Component
public final class SpringUtils implements BeanFactoryPostProcessor {
    //靜態
    private static ConfigurableListableBeanFactory beanFactory; // Spring應用上下文環境

    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory)
            throws BeansException {
        SpringUtils.beanFactory = beanFactory;
    }

    /**
     * 獲取對象
     *
     * @param name
     * @return Object 一個以所給名字註冊的bean的實例
     * @throws org.springframework.beans.BeansException
     *
     */
    @SuppressWarnings("unchecked")
    public static <T> T getBean(String name) throws BeansException {
        return (T) beanFactory.getBean(name);
    }

    /**
     * 獲取類型爲requiredType的對象
     *
     * @param clz
     * @return
     * @throws org.springframework.beans.BeansException
     *
     */
    public static <T> T getBean(Class<T> clz) throws BeansException {
        @SuppressWarnings("unchecked")
        T result = (T) beanFactory.getBean(clz);
        return result;
    }

    /**
     * 如果BeanFactory包含一個與所給名稱匹配的bean定義，則返回true
     *
     * @param name
     * @return boolean
     */
    public static boolean containsBean(String name) {
        return beanFactory.containsBean(name);
    }

    /**
     * 判斷以給定名字註冊的bean定義是一個singleton還是一個prototype。
     * 如果與給定名字相應的bean定義沒有被找到，將會拋出一個異常（NoSuchBeanDefinitionException）
     *
     * @param name
     * @return boolean
     * @throws org.springframework.beans.factory.NoSuchBeanDefinitionException
     *
     */
    public static boolean isSingleton(String name) throws NoSuchBeanDefinitionException {
        return beanFactory.isSingleton(name);
    }

    /**
     * @param name
     * @return Class 註冊對象的類型
     * @throws org.springframework.beans.factory.NoSuchBeanDefinitionException
     *
     */
    public static Class<?> getType(String name) throws NoSuchBeanDefinitionException {
        return beanFactory.getType(name);
    }

    /**
     * 如果給定的bean名字在bean定義中有別名，則返回這些別名
     *
     * @param name
     * @return
     * @throws org.springframework.beans.factory.NoSuchBeanDefinitionException
     *
     */
    public static String[] getAliases(String name) throws NoSuchBeanDefinitionException {
        return beanFactory.getAliases(name);
    }

}

最後redis發佈通道消息

cacheComponent.sendMessage("liveBroadcast", "Barrage-" + String.valueOf(obj));