實現實時視頻聊天功能的源碼在Android平臺上可以使用WebRTC技術。下面是一個簡單的示例：

1. 添加依賴項

在項目的build.gradle文件中添加以下依賴項：

dependencies {
implementation 'org.webrtc:google-webrtc:1.0.32006'
}

2. 創建RTC連接

PeerConnectionFactory.initialize(PeerConnectionFactory.InitializationOptions.builder(context).createInitializationOptions());
PeerConnectionFactory factory = new PeerConnectionFactory();
// 創建本地視頻源
VideoCapturer videoCapturer = createVideoCapturer();
VideoSource videoSource = factory.createVideoSource(videoCapturer.isScreencast());
LocalVideoTrack localVideoTrack = factory.createVideoTrack("video_track", videoSource);
// 創建本地音頻源
AudioSource audioSource = factory.createAudioSource(new MediaConstraints());
LocalAudioTrack localAudioTrack = factory.createAudioTrack("audio_track", audioSource);
// 創建本地媒體流
MediaStream localStream = factory.createLocalMediaStream("local_stream");
localStream.addTrack(localVideoTrack);
localStream.addTrack(localAudioTrack);
// 創建PeerConnection
PeerConnection.RTCConfiguration rtcConfig = new PeerConnection.RTCConfiguration(Collections.singletonList(new PeerConnection.IceServer("stun:stun.l.google.com:19302")));
PeerConnection.Observer pcObserver = new PeerConnection.Observer() {
// 實現對方視頻流的回調
@Override
public void onAddStream(MediaStream mediaStream) {
// 獲取對方的視頻軌道
VideoTrack remoteVideoTrack = mediaStream.videoTracks.getFirst();
// 顯示對方的視頻
remoteVideoTrack.addSink(remoteVideoView);
}
// 其他回調方法...
};
PeerConnection peerConnection = factory.createPeerConnection(rtcConfig, pcObserver);
peerConnection.addStream(localStream);

3. 發起視頻通話

// 創建SessionDescription
SdpObserver sdpObserver = new SdpObserver() {
@Override
public void onCreateSuccess(SessionDescription sessionDescription) {
// 設置本地的SessionDescription
peerConnection.setLocalDescription(sdpObserver, sessionDescription);
// 發送本地的SessionDescription到對方
sendSessionDescription(sessionDescription);
}
// 其他回調方法...
};
peerConnection.createOffer(sdpObserver, new MediaConstraints());

4. 接收視頻通話

// 接收對方的SessionDescription
SessionDescription remoteDescription = receiveSessionDescription();
peerConnection.setRemoteDescription(sdpObserver, remoteDescription);
// 創建Answer
peerConnection.createAnswer(sdpObserver, new MediaConstraints());

5. 建立視頻連接

// 設置對方的SessionDescription
peerConnection.setRemoteDescription(sdpObserver, remoteDescription);
// 添加ICE候選
peerConnection.addIceCandidate(candidate);
// 建立連接
peerConnection.createAnswer(sdpObserver, new MediaConstraints());

這只是一個簡單的示例，實際的視頻聊天功能需要處理更多的細節，例如處理ICE候選、處理連接狀態變化、處理媒體流的傳輸等。完整的實現可能需要更多的代碼和邏輯。