实现场景：每在小程序中添加一条数据时，后台将主动推送一个标记给PC端，PC端接收到标记将进行自动播放音频。

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

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

import org.springframework.stereotype.Component;

import javax.websocket.OnClose;
import javax.websocket.OnError;
import javax.websocket.OnOpen;
import javax.websocket.Session;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.concurrent.CopyOnWriteArraySet;

@Component
@ServerEndpoint("/websocket")
public class WebSocketServer {


    private static final CopyOnWriteArraySet<WebSocketServer> connections = new CopyOnWriteArraySet<>();
    private Session session;

    @OnOpen
    public void onOpen(Session session) {
        this.session = session;
        connections.add(this);
        this.sendMessage("0");
    }

    @OnClose
    public void onClose() {
        connections.remove(this);
        System.out.println("连接关闭: " + session.getId());
    }

    @OnError
    public void onError(Throwable error) {
        System.out.println("错误信息："+error.getMessage());
        error.printStackTrace();
    }

    private void sendMessage(String message) {
        try {
            this.session.getBasicRemote().sendText(message);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void broadcast(String message) {
        for (WebSocketServer client : connections) {
            client.sendMessage(message);
        }
    }

}

@Override
    public void addUser(req req) {
        QueryWrapper<User> userWrapper = new QueryWrapper<>();
        userWrapper .eq("name",req.getName());
        User u = userMapper.selectOne(userWrapper);
        if (u == null){
            WebSocketServer.broadcast("1");
        }
    }

每次小程序调用 addUser() 方法时，都会执行 WebSocketServer.broadcast("1"); 这时候触发主动推送消息给PC端。

---

 

遇到的问题：

         Error during WebSocket handshske: Unexpected response code: 200

解决方案：

        本地项目中存在账号密码验证的过滤器，其中 /websocket 进行了转发，所以需要过滤请求

 

重新启动项目即可。