怎么将getUserMedia获取的流传给java后端

你可以使用WebRTC技术将getUserMedia获取的流传给Java后端。具体步骤如下：

1. 在前端使用getUserMedia获取流，并将流发送给后端。

const constraints = { audio: true, video: true };
navigator.mediaDevices.getUserMedia(constraints)
  .then(stream => {
    // 将stream发送给后端
    sendStreamToBackend(stream);
  })
  .catch(error => {
    console.error(error);
  });

function sendStreamToBackend(stream) {
  // 使用WebRTC技术将stream传输给后端
  // 可以使用Socket.IO或WebSockets来发送stream
  const socket = io();
  const peer = new RTCPeerConnection();

  peer.addStream(stream);

  peer.createOffer()
    .then(offer => {
      peer.setLocalDescription(offer);
      socket.emit('offer', offer);
    });

  socket.on('answer', answer => {
    peer.setRemoteDescription(answer);
  });

  peer.onicecandidate = event => {
    if (event.candidate) {
      socket.emit('candidate', event.candidate);
    }
  };

  socket.on('candidate', candidate => {
    peer.addIceCandidate(candidate);
  });
}

2. 在后端接收流，并进行处理。

import org.glassfish.tyrus.client.ClientManager;

import javax.websocket.*;
import java.io.IOException;
import java.net.URI;

@ClientEndpoint
public class WebsocketClient {

    private Session session;

    @OnOpen
    public void onOpen(Session session) {
        this.session = session;
    }

    @OnMessage
    public void onMessage(String message) {
        // 接收到消息后进行处理
        System.out.println(message);
    }

    @OnClose
    public void onClose(Session session, CloseReason closeReason) {
        System.out.println("WebSocket closed: " + closeReason);
    }

    @OnError
    public void onError(Session session, Throwable throwable) {
        System.out.println("WebSocket error: " + throwable.getMessage());
    }

    public void connect(String uri) throws IOException, DeploymentException {
        ClientManager client = ClientManager.createClient();
        client.connectToServer(this, URI.create(uri));
    }

    public void send(String message) throws IOException {
        session.getBasicRemote().sendText(message);
    }
}

import javax.websocket.*;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.HashSet;
import java.util.Set;

@ServerEndpoint("/stream")
public class StreamEndpoint {

    private static Set<Session> sessions = new HashSet<>();

    @OnOpen
    public void onOpen(Session session) {
        sessions.add(session);
    }

    @OnMessage
    public void onMessage(Session session, String message) {
        // 接收到消息后进行处理
        System.out.println(message);

        // 将消息发送给所有连接的客户端
        for (Session s : sessions) {
            try {
                s.getBasicRemote().sendText(message);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    @OnClose
    public void onClose(Session session) {
        sessions.remove(session);
    }

    @OnError
    public void onError(Session session, Throwable throwable) {
        throwable.printStackTrace();
    }
}

上述代码中，`WebsocketClient`是Java后端连接WebSocket服务器的客户端，`StreamEndpoint`是WebSocket服务器的端点，用于接收从前端发送来的流数据。你可以根据具体需求对代码进行修改。