java后端使用websocket实现与客户端之间接收及发送消息

客户端请求websocket接口，连接通道=》我这边业务成功客户端发消息=》客户端自动刷新。

接口：ws://localhost:8080/websocket/xx

import org.springframework.web.socket.config.annotation.WebSocketConfigurer;
import org.springframework.web.socket.server.standard.ServerEndpointExporter;

/**
 * @author Administrator
 */
@Configuration
public class WebSocketConfig implements WebSocketConfigurer {

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

import cn.hutool.core.util.StrUtil;
import xx.Constant;
import xx.utils.JwtHelper;
import xx.utils.RedisUtil;
import xx.SpringUtil;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;
import javax.websocket.*;
import javax.websocket.server.PathParam;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.CopyOnWriteArraySet;
@Component
@Slf4j
@ServerEndpoint("/websocket/{key}")
public class WebSocketService {
    //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;
    private static CopyOnWriteArraySet<WebSocketService> webSockets = new CopyOnWriteArraySet<>();
    //用来存放每个客户端对应的websocket对象
    private static Map<String,Session> sessionPool = new HashMap<>();
    private String userIdStr;
    private static WebSocketService webSocketService;
    @PostConstruct
    public void init(){
        webSocketService = this;
    }

    /**
     * 连接成功后调用的方法
     * @param session
     * @param key
     */
    @OnOpen
    public void onOpen(Session session,@PathParam("key") String key){
        //key作为前端传给后端的token
        this.session = session;
        //从token中获取到的userId当作区分websocket客户端的key
        String userIdStr = JwtHelper.verifyTokenAndGetUserId(key);
        this.userIdStr = userIdStr;
        sessionPool.put(userIdStr,session);
        if (sessionPool.get(userIdStr) == null){
            webSockets.add(this);
        }
        webSockets.add(this);
        log.info("websocket连接成功");
        log.info("websocket有新的连接，连接总数为"+webSockets.size());
    }

    /**
     * 连接关闭调用的方法
     */
    @OnClose
    public void onClose(){
        sessionPool.remove(userIdStr);
        webSockets.remove(this);
        log.info("websocket连接关闭");
    }

    /**
     * 收到客户端消息后调用的方法，根据业务要求进行处理，这里就简单地将收到的消息直接群发推送出去
     * @param message 客户端发送过来的消息
     */
    @OnMessage
    public void onMessage(String message){
        String key = Constant.BID_SUCCESS+userIdStr;
        if (StrUtil.isNotBlank(message)){
            if(message.equals("heartbeat")){
                sendTextMessage(key,"已连接");
            }else{
                RedisUtil redisUtil = SpringUtil.getBean(RedisUtil.class);
                //根据业务条件判断发送消息
                String result = String.valueOf(redisUtil.get(key));
                if (StrUtil.isNotBlank(result) && result.equals(Constant.SUCCESS)){
                    sendAllMessage("ok");
                    //发送之后删除key
                    redisUtil.delete(key);
                }
            }
        }
        log.info("WebSocket收到客户端消息："+message);
    }

    /**
     * 实现服务器主动推送消息
     * @param key
     * @param message
     */
    private void sendTextMessage(String key, String message) {
        Session session = sessionPool.get(key);
        if (session != null){
            try {
                session.getBasicRemote().sendText(message);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    public void sendAllMessage(String message){
        log.info("websocket消息全部人员消息:"+message);
        for (WebSocketService apiWebSocketService:webSockets){
            try{
                if (apiWebSocketService.session.isOpen()){
                    apiWebSocketService.session.getAsyncRemote().sendText(message);
                }
            }catch (Exception e){
                e.printStackTrace();
                log.error("全部人员发送消息失败:",e.getMessage());
            }
        }
    }
    /**
     * 发生错误时的回调函数
     * @param session
     * @param error
     */
    @OnError
    public void onError(Session session,Throwable error){
        log.error("发生错误");
        error.printStackTrace();
    }

}

经测试，成功

如果是线上服务器连接，则需要在nginx里配置websocket相关内容,再重启nginx，代码如下

server {
        listen       443 ssl;
        server_name  api.kadecard.com;
        ssl_certificate      cert.pem;
        ssl_certificate_key  cert.key; 
         ssl_session_cache    shared:SSL:1m;
        ssl_session_timeout  5m;
 
       # ssl_ciphers  HIGH:!aNULL:!MD5;
       # ssl_prefer_server_ciphers  on;
    
        ssl_ciphers  ECDHE-RSA-AES128-GCM-SHA256:ECDHE:ECDH:AES:HIGH:!NULL:!aNULL:!MD5:!ADH:!RC4;
        ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
        ssl_prefer_server_ciphers  on;
        
        location / {
           proxy_pass http://xx:7878/;
     
        }    
        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }
    
    #websocket 这里的websocket是后端websocket接口的接口名称 
      location /websocket {
            rewrite ^/ws$ / break;
            rewrite ^/ws(.*)$ $1 break;
            proxy_pass http://127.0.0.1:7878;
            proxy_http_version 1.1;    #websoket必须要使用的协议，http 1.1
            proxy_set_header Upgrade $http_upgrade;  #要使用websocket协议时，响应http升级请求
            proxy_set_header Connection "upgrade";
            proxy_set_header X-real-ip $remote_addr;
             proxy_set_header X-Forwarded-For $remote_addr;
        proxy_read_timeout 600s;
      }
    }

本地连接的时候用的是ws://,因为是http链接，但是如果是服务器连接，且支持https连接方式，则就需要用wss://的连接方式。