1. 在build.gradle中添加依赖项

dependencies {
    ...
    implementation 'com.google.android.gms:play-services-vision:20.1.3'
    implementation 'com.google.android.material:material:1.2.1'
    implementation 'androidx.camera:camera-core:1.1.0-alpha06'
    implementation 'androidx.camera:camera-camera2:1.1.0-alpha06'
    implementation 'androidx.camera:camera-lifecycle:1.1.0-alpha06'
}

2. 在MainActivity类中声明变量

private lateinit var cameraExecutor: ExecutorService
private lateinit var viewFinder: TextureView
private lateinit var outputDirectory: File
private val REQUEST_CODE_PERMISSIONS = 10
private val REQUIRED_PERMISSIONS = arrayOf(Manifest.permission.CAMERA, Manifest.permission.RECORD_AUDIO)

3. 在onCreate方法中初始化变量和设置TextureView.SurfaceTextureListener

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)

    viewFinder = findViewById(R.id.view_finder)

    if (allPermissionsGranted()) {
        viewFinder.post { startCamera() }
    } else {
        ActivityCompat.requestPermissions(
            this, REQUIRED_PERMISSIONS, REQUEST_CODE_PERMISSIONS)
    }

    cameraExecutor = Executors.newSingleThreadExecutor()
    outputDirectory = getOutputDirectory()
    viewFinder.surfaceTextureListener = surfaceTextureListener
}

4. 在startCamera方法中配置CameraX和Preview

private fun startCamera() {
    val previewConfig = PreviewConfig.Builder().apply {
        setTargetResolution(Size(640, 480))
    }.build()

    val preview = Preview(previewConfig)

    preview.setOnPreviewOutputUpdateListener {
        viewFinder.surfaceTexture = it.surfaceTexture
    }

    val videoFile = File(outputDirectory, "video.mp4").apply {
        createNewFile()
    }
    val videoCaptureConfig = VideoCaptureConfig.Builder().apply {
        setTargetResolution(Size(640, 480))
        setTargetRotation(viewFinder.display.rotation)
        setAudio(Audio.ON)
    }.build()

    val videoCapture = VideoCapture(videoCaptureConfig)

    findViewById(R.id.camera_capture_button).setOnClickListener {
        videoCapture.startRecording(videoFile, object: VideoCapture.OnVideoSavedListener {
            override fun onError(videoCaptureError: Int, message: String, cause: Throwable?) {
                Log.d("Capture error $videoCaptureError", message)
            }

            override fun onVideoSaved(file: File) {
                Log.d("Video saved", file.absolutePath)
                // send the video over the network
                sendVideoOverNetwork(file)
            }
        })
    }

    CameraX.bindToLifecycle(this, preview, video