Spring Cloud微服务使用webSocket的方法

webSocket

webSocket长连接是一种在单个tcp连接上进行全双工通信的协议，允许双向数据推送。一般微服务提供的restful API只是对前端请求做出相应。使用webSocket可以实现后端主动向前端推送消息。

网关配置

spring cloud 的网关组件有zuul和getway

getway

base:
  config:
    nacos:
      nacoshost: localhost
      port: 8848

spring:
  application:
    name: gateway
  main:
    allow-bean-definition-overriding: true
  cloud:
    nacos:
      discovery:
        server-addr: ${base.config.nacos.nacoshost}:${base.config.nacos.port}
    gateway:
      discovery:
        locator:
          enabled: true
      routes:
        #  websocket
        - id: CLOUD-WEBSOCKET
          uri: lb:ws://cloud-websocket
          predicates:
            - Path=/cloud-websocket/**
server:
  port: 8888

配置网关的时候注意添加ws协议。

zuul

zuul只能管理http请求，不推荐使用zuul管理websocket连接，推荐直连。

服务端

添加maven依赖

            org.springframework.boot
            spring-boot-starter-websocket
        

添加webSocket 配置

@Configuration
@EnableWebSocket
public class WebsocketConfiguration implements WebSocketConfigurer {
    @Override
    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        // webSocket通道
        // 指定处理器和路径
        registry.addHandler(new WebSocketHandler(), "/websocket")
                // 指定自定义拦截器
                .addInterceptors(new WebSocketInterceptor())
                // 允许跨域
                .setAllowedOrigins("*");
        // sockJs通道
        registry.addHandler(new WebSocketHandler(), "/sock-js")
                .addInterceptors(new WebSocketInterceptor())
                .setAllowedOrigins("*")
                // 开启sockJs支持
                .withSockJS();
    }
}

添加处理器

package com.auexpress.cloud.handler;

import com.alibaba.fastjson.JSONObject;
import org.apache.commons.lang3.StringUtils;
import org.springframework.web.socket.*;
import org.springframework.web.socket.handler.AbstractWebSocketHandler;

import java.io.IOException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

/**
 * @Description
 * @ClassName WebSocketHandler
 * @Author HYSong
 * @date 2020.04.14 10:08
 */
public class WebSocketHandler extends AbstractWebSocketHandler {
    /**
     *  存储sessionId和webSocketSession
     *  需要注意的是，webSocketSession没有提供无参构造，不能进行序列化，也就不能通过redis存储
     *  在分布式系统中，要想别的办法实现webSocketSession共享
     */
    private static Map sessionMap = new ConcurrentHashMap<>();
    private static Map userMap = new ConcurrentHashMap<>();

    /**
     * webSocket连接创建后调用
     */
    @Override
    public void afterConnectionEstablished(WebSocketSession session) {
        // 获取参数
        String user = String.valueOf(session.getAttributes().get("user"));
        userMap.put(user, session.getId());
        sessionMap.put(session.getId(), session);
    }

    /**
     * 接收到消息会调用
     */
    @Override
    public void handleMessage(WebSocketSession session, WebSocketMessage message) throws Exception {
        JSONObject jsonObject = JSONObject.parseObject(message.getPayload().toString());
        String content = jsonObject.getString("content");
        String targetAdminId = jsonObject.getString("targetId");
        if("0".equals(targetAdminId)){
            //  推送给所有人
            userMap.forEach((key,value)->{
                try {
                    this.sendMessage(key,content);
                } catch (IOException e) {
                    e.printStackTrace();
                }
            });
        }else{
            sendMessage("1", content);
        }
    }

    /**
     * 连接出错会调用
     */
    @Override
    public void handleTransportError(WebSocketSession session, Throwable exception) {
        sessionMap.remove(session.getId());
    }

    /**
     * 连接关闭会调用
     */
    @Override
    public void afterConnectionClosed(WebSocketSession session, CloseStatus status) {
        sessionMap.remove(session.getId());
    }

    @Override
    public boolean supportsPartialMessages() {
        return false;
    }

    /**
     * 后端发送消息
     */
    public void sendMessage(String user, String message) throws IOException {
        String sessionId = userMap.get(user);
        if (StringUtils.isEmpty(sessionId)) {
            return;
        }
        WebSocketSession session = sessionMap.get(sessionId);
        if (session == null) {
            return;
        }
        session.sendMessage(new TextMessage(message));
    }
}

添加拦截器

package com.auexpress.cloud.interceptor;

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.HandshakeInterceptor;

import java.util.Map;

/**
 * @Description
 * @ClassName WebSocketInterceptor
 * @Author HYSong
 * @date 2020.04.14 10:09
 */
public class WebSocketInterceptor implements HandshakeInterceptor {
    /**
     * handler处理前调用,attributes属性最终在WebSocketSession里,
     * 可能通过webSocketSession.getAttributes().get(key值)获得
     */
    @Override
    public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Map attributes) {
        if (request instanceof ServletServerHttpRequest) {
            ServletServerHttpRequest serverHttpRequest = (ServletServerHttpRequest) request;
            // 获取请求路径携带的参数
            String user = serverHttpRequest.getServletRequest().getParameter("user");
            attributes.put("user", user);
            return true;
        } else {
            return false;
        }
    }

    @Override
    public void afterHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Exception exception) {

    }
}

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