如何在Android应用的VideoView组件中打开并显示摄像头实时画面

你当前使用的MediaStore.ACTION_IMAGE_CAPTURE意图是唤起系统相机应用完成拍照操作，逻辑本身就是跳转外部应用，无法实现将相机预览内嵌到你自有应用的组件中。

优先推荐使用Jetpack CameraX实现，适配成本低、兼容性好，无需自行处理各机型适配问题；如果必须使用VideoView承载预览，可以用Camera2 API实现。

前置准备：配置权限 #

在AndroidManifest.xml中添加相机相关声明：

<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera.any" />

Android 6.0及以上版本需要在运行时动态申请CAMERA权限，权限申请通过后再执行相机初始化逻辑。

方案1：Jetpack CameraX实现（推荐） #

1. 引入依赖 #

在模块级build.gradle中添加CameraX依赖：

dependencies {
    def camerax_version = "1.3.0"
    implementation "androidx.camera:camera-core:$camerax_version"
    implementation "androidx.camera:camera-camera2:$camerax_version"
    implementation "androidx.camera:camera-lifecycle:$camerax_version"
    implementation "androidx.camera:camera-view:$camerax_version"
}

2. 修改布局 #

把原有VideoView替换为CameraX专属预览组件：

<androidx.camera.view.PreviewView
    android:id="@+id/previewView"
    android:layout_width="366dp"
    android:layout_height="437dp"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.355"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:layout_constraintVertical_bias="0.088" />

3. 初始化相机 #

权限申请通过后调用以下方法即可完成预览渲染：

private fun startCamera() {
    val cameraProviderFuture = ProcessCameraProvider.getInstance(this)
    cameraProviderFuture.addListener({
        val cameraProvider = cameraProviderFuture.get()
        val preview = Preview.Builder().build().also {
            it.setSurfaceProvider(previewView.surfaceProvider)
        }
        // 配置为前置摄像头，和你原有需求对齐
        val cameraSelector = CameraSelector.DEFAULT_FRONT_CAMERA
        try {
            cameraProvider.unbindAll()
            // 绑定页面生命周期，页面销毁时自动释放相机
            cameraProvider.bindToLifecycle(this, cameraSelector, preview)
        } catch(exc: Exception) {
            // 自行处理相机初始化失败逻辑
        }
    }, ContextCompat.getMainExecutor(this))
}

方案2：Camera2 API输出到VideoView #

如果必须保留原有VideoView组件，可通过以下核心逻辑实现预览输出：

1. 先给VideoView配置Surface #

在页面初始化时添加配置：

videoView.holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS)
videoView.holder.addCallback(object : SurfaceHolder.Callback {
    override fun surfaceCreated(holder: SurfaceHolder) {
        // Surface创建成功后再启动相机
        startCameraToVideoView(holder.surface)
    }
    override fun surfaceChanged(holder: SurfaceHolder, format: Int, width: Int, height: Int) {}
    override fun surfaceDestroyed(holder: SurfaceHolder) {}
})

2. 实现相机预览输出逻辑 #

@SuppressLint("MissingPermission")
private fun startCameraToVideoView(surface: Surface) {
    val cameraManager = getSystemService(CAMERA_SERVICE) as CameraManager
    // 筛选前置摄像头
    val frontCameraId = cameraManager.cameraIdList.firstOrNull { id ->
        cameraManager.getCameraCharacteristics(id)
            .get(CameraCharacteristics.LENS_FACING) == CameraCharacteristics.LENS_FACING_FRONT
    } ?: return
    val captureRequestBuilder = cameraManager.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW)
    captureRequestBuilder.addTarget(surface)
    cameraManager.openCamera(frontCameraId, object : CameraDevice.StateCallback() {
        override fun onOpened(camera: CameraDevice) {
            camera.createCaptureSession(
                listOf(surface),
                object : CameraCaptureSession.StateCallback() {
                    override fun onConfigured(session: CameraCaptureSession) {
                        session.setRepeatingRequest(captureRequestBuilder.build(), null, null)
                    }
                    override fun onConfigureFailed(session: CameraCaptureSession) {}
                },
                null
            )
        }
        override fun onDisconnected(camera: CameraDevice) {
            camera.close()
        }
        override fun onError(camera: CameraDevice, error: Int) {
            camera.close()
        }
    }, null)
}

内容的提问来源于stack exchange，提问作者Muhammad Uzair Ehsan