Android实战教程：手把手教你开发儿童手机远程监控App实现WebRtc摄像头切换与桌面共享功能

作者：袖梨 2026-05-29

在完成嘟宝与嘟妈之间的WebRTC音视频通信后，本文将详细介绍远程切换摄像头和屏幕共享功能的实现方法。

概述

前文实现了嘟宝与嘟妈之间的实时音视频通信功能，主要包含以下关键步骤：

嘟妈通过扫描二维码完成设备绑定
嘟妈发起呼叫请求建立WebRTC连接
嘟宝设备采集并传输多媒体视频流至嘟妈端

切换前后摄像头

嘟妈端可通过发送信令指令远程切换嘟宝设备的摄像头，整个过程视频流保持稳定，实现画面无缝过渡。

获取相机采集工具
获取相机视频流

private VideoCapturer createCameraCapturer(boolean isFront) {
    Camera2Enumerator enumerator = new Camera2Enumerator(context.getApplicationContext());
    final String[] deviceNames = enumerator.getDeviceNames();
    for (String deviceName : deviceNames) {
        if (isFront ? enumerator.isFrontFacing(deviceName) : enumerator.isBackFacing(deviceName)) {
            VideoCapturer videoCapturer = enumerator.createCapturer(deviceName, null);
            mCamCapture = (CameraVideoCapturer) videoCapturer;
            if (videoCapturer != null) {
                return videoCapturer;
            }
        }
    }
    return null;
}

此函数通过枚举设备上的摄像头，根据参数返回前置或后置相机的采集工具。

private VideoTrack getVideoTrack(){
    surfaceTextureHelper = SurfaceTextureHelper.create("CaptureThread", eglBase.getEglBaseContext());
    VideoCapturer videoCapturer = createCameraCapturer(true);
    VideoSource videoSource = factory.createVideoSource(videoCapturer.isScreencast());
    videoCapturer.initialize(surfaceTextureHelper, context.getApplicationContext(), videoSource.getCapturerObserver());
    videoCapturer.startCapture(480, 640, 30);
    VideoTrack videoTrack=   factory.createVideoTrack("100", videoSource);
    videoTrack.enabled();
    return videoTrack;
}

该函数调用createCameraCapturer选择前置摄像头，获取视频流。其中通过强制类型转换获得mCamCapture变量，用于后续相机切换操作。

public void changeCam(){
    if (mCamCapture != null) {
        mCamCapture.switchCamera(null);
    }
}

屏幕共享

嘟妈可通过信令请求查看嘟宝屏幕内容，此功能需在嘟宝设备上获得用户授权。

在后台服务中配置屏幕共享权限
在MainActivity中申请屏幕共享权限
获取用户授权后的Intent变量用于捕获屏幕视频流

mediaProjection服务类型允许后台捕获屏幕内容。

public void startprojectionManager(){
    @SuppressLint({"NewApi", "LocalSuppress"}) MediaProjectionManager projectionManager = (MediaProjectionManager)getSystemService(MEDIA_PROJECTION_SERVICE);
    @SuppressLint({"NewApi", "LocalSuppress"}) Intent intent = projectionManager.createScreenCaptureIntent();
    ActivityResultLauncher screenCaptureLauncher;
    screenCaptureLauncher=registerForActivityResult(new ActivityResultContracts.StartActivityForResult(), result -> {
        if (result.getResultCode() == RESULT_OK) {
            Intent data = result.getData();
            MyWebRtc.i=data;
        }
        else {
        }
    });
    screenCaptureLauncher.launch(intent);
}

此代码段申请屏幕共享权限，并将授权结果存储在MyWebRtc.i变量中。

public void getScreenVideo() {
    surfaceTextureHelperscreen = SurfaceTextureHelper.create("CaptureThread1", eglBase.getEglBaseContext());
    VideoCapturer screenCapturer=new ScreenCapturerAndroid(i, new MediaProjection.Callback() {
        @Override
        public void onStop() {
            super.onStop();
        }
    });
    VideoSource screenVideoSource = factory.createVideoSource(screenCapturer.isScreencast());
    VideoTrack screenVideoTrack = factory.createVideoTrack("102", screenVideoSource);
    screenCapturer.initialize(surfaceTextureHelperscreen, context.getApplicationContext(), screenVideoSource.getCapturerObserver());
    screenCapturer.startCapture(640, 480, 25);
    localVideoSender.setTrack(screenVideoTrack, true);
}

此方法实现了屏幕视频流的捕获和传输功能。