[网络协议]SpringBoot集成WebSocket

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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。

为什么需要 WebSocket？
初次接触 WebSocket 的人，都会问同样的问题：我们已经有了 HTTP 协议，为什么还需要另一个协议？它能带来什么好处？

答案很简单，因为 HTTP 协议有一个缺陷：通信只能由客户端发起，HTTP 协议做不到服务器主动向客户端推送信息。

?1、maven依赖

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

2、WebSocketConfig?

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

/**
 * 开启WebSocket支持
 */
@Configuration  
public class WebSocketConfig {  
    
    @Bean  
    public ServerEndpointExporter serverEndpointExporter() {  
        return new ServerEndpointExporter();  
    }  
  
} 

?3、WebSocketServer

因为WebSocket是类似客户端服务端的形式(采用ws协议)，那么这里的WebSocketServer其实就相当于一个ws协议的Controller

?新建websocket的Controller

直接@ServerEndpoint("/websocket") 、@Component启用即可，然后在里面实现@OnOpen开启连接，@onClose关闭连接，@onMessage接收消息等方法。

新建一个ConcurrentHashMap servers 客户端连接信息

用于接收当前Session的WebSocket，方便IM之间对当前连接进行推送消息。

import com.alibaba.fastjson.JSON;
import io.demo.common.constant.Constant;
import io.demo.websocket.config.WebSocketConfig;
import io.demo.websocket.data.MessageData;
import io.demo.websocket.data.WebSocketData;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;

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

@Slf4j
@Component
@ServerEndpoint(value = "/websocket", configurator = WebSocketConfig.class)
public class WebSocketServer {
    /**
     * 客户端连接信息
     */
    private static Map<String, WebSocketData> servers = new ConcurrentHashMap<>();

    @OnOpen
    public void open(Session session) {
        Long userId = (Long) session.getUserProperties().get(Constant.USER_KEY);

        servers.put(session.getId(), new WebSocketData(userId, session));
    }

    @OnClose
    public void onClose(Session session) {
        //客户端断开连接
        servers.remove(session.getId());
        log.debug("websocket close, session id：" + session.getId());
    }

    @OnError
    public void onError(Session session, Throwable throwable) {
        servers.remove(session.getId());
        log.error(throwable.getMessage(), throwable);
    }

    @OnMessage
    public void onMessage(Session session, String msg) {
        log.info("session id: " + session.getId()+"， message：" + msg);
    }

    /**
     * 发送信息
     * @param userIdList     用户ID列表
     * @param message       消息内容
     */
    public void sendMessage(List<Long> userIdList, MessageData<?> message) {
        userIdList.forEach(userId -> sendMessage(userId, message));
    }

    /**
     * 发送信息
     * @param userId      用户ID
     * @param message    消息内容
     */
    public void sendMessage(Long userId, MessageData<?> message) {
        servers.values().forEach(info -> {
            if (userId.equals(info.getUserId())) {
                sendMessage(info.getSession(), message);
            }
        });
    }

    /**
     * 发送信息给全部用户
     * @param message    消息内容
     */
    public void sendMessageAll(MessageData<?> message) {
        servers.values().forEach(info -> sendMessage(info.getSession(), message));
    }

    public void sendMessage(Session session, MessageData<?> message) {
        try {
            session.getBasicRemote().sendText(JSON.toJSONString(message));
        } catch (IOException e) {
            log.error("send message error，" + e.getMessage(), e);
        }
    }
}

?4、消息推送

可以在自己的Controller写个方法调用WebSocketServer.sendMessage()。

import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.servlet.ModelAndView;
import java.io.IOException;

/**
 * WebSocketController
 */
@RestController
public class DemoController {
    @Autowired
    private WebSocketServer webSocketServer;

 
    @RequestMapping("/push/{toUserId}")
    public ResponseEntity<String> pushToWeb(@PathVariable String toUserId) throws IOException {
        String message="WebSocket";
        WebSocketServer.sendMessage(toUserId,message);
        return ResponseEntity.ok("MSG SEND SUCCESS");
    }
}

5、页面发起?

 test () {
      this.$http.get('/push/'+toUserId).then(({ data: res }) => {
        if (res.code !== 0) {
          return this.$message.error(res.msg)
        } 
      }).catch(() => { })

      var vue = this
      socket = new WebSocket(`${window.SITE_CONFIG['socketURL']}`)
      socket.onopen = function () { }
      socket.onerror = function () {
        vue.$notify.error({
          title: vue.$t('notice.disconnect'),
          message: vue.$t('notice.disconnectMessage')
        })
      }
      socket.onmessage = function (evt) {
        const result = JSON.parse(evt.data)
        if (result.type === 0) {
          vue.$notify({
            title: vue.$t('notice.new'),
            message: result.msg,
            type: 'info',
            duration: 5000
          })
        }
      }