android使用WebRTC实现通信的案例

以下是一个简单的 Android 应用程序，使用 WebRTC 实现基本的视频聊天功能：

1. 首先，添加以下依赖项到项目的 build.gradle 文件中：

dependencies {
    implementation 'org.webrtc:google-webrtc:1.0.+'
}

2. 在 AndroidManifest.xml 文件中添加以下权限：

<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.INTERNET" />

3. 在布局文件中添加 SurfaceView 用于显示远程视频：

<SurfaceView
    android:id="@+id/remote_video_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

4. 在 MainActivity.java 中实现 WebRTC 相关功能：

import org.webrtc.*;

public class MainActivity extends AppCompatActivity implements PeerConnection.Observer {

    private PeerConnectionFactory factory;
    private PeerConnection peerConnection;
    private SurfaceView remoteView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // 初始化 PeerConnectionFactory
        PeerConnectionFactory.initialize(PeerConnectionFactory.InitializationOptions.builder(this).createInitializationOptions());
        factory = PeerConnectionFactory.builder().createPeerConnectionFactory();

        // 获取远程视频的 SurfaceView
        remoteView = findViewById(R.id.remote_video_view);

        // 创建 PeerConnection
        PeerConnection.RTCConfiguration rtcConfig = new PeerConnection.RTCConfiguration(Collections.singletonList(new PeerConnection.IceServer("stun:stun.l.google.com:19302")));
        peerConnection = factory.createPeerConnection(rtcConfig, this);
    }

    // 实现 PeerConnection.Observer 接口中的回调方法
    @Override
    public void onIceCandidate(IceCandidate iceCandidate) {
        // 发送 ICE 候选项到对方
    }

    @Override
    public void onIceCandidatesRemoved(IceCandidate[] iceCandidates) {

    }

    @Override
    public void onSignalingChange(PeerConnection.SignalingState signalingState) {

    }

    @Override
    public void onIceConnectionChange(PeerConnection.IceConnectionState iceConnectionState) {

    }

    @Override
    public void onConnectionChange(PeerConnection.PeerConnectionState newState) {

    }

    @Override
    public void onSelectedCandidatePairChanged(CandidatePairChangeEvent event) {

    }

    @Override
    public void onAddStream(MediaStream mediaStream) {
        // 将远程视频渲染到 SurfaceView 上
        VideoTrack remoteVideoTrack = mediaStream.videoTracks.get(0);
        remoteVideoTrack.addSink(remoteView.getHolder().getSurface());
    }

    @Override
    public void onDataChannel(DataChannel dataChannel) {

    }

    @Override
    public void onRenegotiationNeeded() {

    }

    @Override
    public void onRemoveStream(MediaStream mediaStream) {

    }

    @Override
    public void onTrack(RtpTransceiver transceiver) {

    }
}

5. 在需要进行视频通话的时候，创建并发送 Offer：

MediaConstraints constraints = new MediaConstraints();
constraints.mandatory.add(new MediaConstraints.KeyValuePair("OfferToReceiveAudio", "true"));
constraints.mandatory.add(new MediaConstraints.KeyValuePair("OfferToReceiveVideo", "true"));
peerConnection.createOffer(new SdpObserver() {
    @Override
    public void onCreateSuccess(SessionDescription sessionDescription) {
        peerConnection.setLocalDescription(new SdpObserver() {
            @Override
            public void onCreateSuccess(SessionDescription sessionDescription) {

            }

            @Override
            public void onSetSuccess() {
                // 发送 Offer 给对方
            }

            @Override
            public void onCreateFailure(String s) {

            }

            @Override
            public void onSetFailure(String s) {

            }
        }, sessionDescription);
    }

    @Override
    public void onSetSuccess() {

    }

    @Override
    public void onCreateFailure(String s) {

    }

    @Override
    public void onSetFailure(String s) {

    }
}, constraints);

6. 在接收到对方的 Offer 时，创建并发送 Answer：

peerConnection.setRemoteDescription(new SdpObserver() {
    @Override
    public void onCreateSuccess(SessionDescription sessionDescription) {

    }

    @Override
    public void onSetSuccess() {
        MediaConstraints constraints = new MediaConstraints();
        constraints.mandatory.add(new MediaConstraints.KeyValuePair("OfferToReceiveAudio", "true"));
        constraints.mandatory.add(new MediaConstraints.KeyValuePair("OfferToReceiveVideo", "true"));
        peerConnection.createAnswer(new SdpObserver() {
            @Override
            public void onCreateSuccess(SessionDescription sessionDescription) {
                peerConnection.setLocalDescription(new SdpObserver() {
                    @Override
                    public void onCreateSuccess(SessionDescription sessionDescription) {

                    }

                    @Override
                    public void onSetSuccess() {
                        // 发送 Answer 给对方
                    }

                    @Override
                    public void onCreateFailure(String s) {

                    }

                    @Override
                    public void onSetFailure(String s) {

                    }
                }, sessionDescription);
            }

            @Override
            public void onSetSuccess() {

            }

            @Override
            public void onCreateFailure(String s) {

            }

            @Override
            public void onSetFailure(String s) {

            }
        }, constraints);
    }

    @Override
    public void onCreateFailure(String s) {

    }

    @Override
    public void onSetFailure(String s) {

    }
}, offer);

7. 在接收到对方的 Answer 时，设置远程描述：

peerConnection.setRemoteDescription(new SdpObserver() {
    @Override
    public void onCreateSuccess(SessionDescription sessionDescription) {

    }

    @Override
    public void onSetSuccess() {

    }

    @Override
    public void onCreateFailure(String s) {

    }

    @Override
    public void onSetFailure(String s) {

    }
}, answer);

以上是一个简单的 Android 应用程序，使用 WebRTC 实现基本的视频聊天功能的案例。