API 33以下版本相机无法工作问题排查求助

问题描述 #

实现带音频录制的相机功能，使用Dexter做权限校验，视频可保存到设备文件夹。该功能在API32及以上设备正常运行，但API33以下设备无法启动，调试发现Dexter的权限校验逻辑未正常执行。

原始代码片段 #

AndroidManifest.xml #

<uses-feature android:name="android.hardware.camera" android:required="false" />
<uses-feature android:name="android.hardware.camera.any" android:required="false" />
<uses-feature android:name="android.hardware.camera.autofocus" android:required="false" />
<uses-feature android:name="android.hardware.camera.flash" android:required="false" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-feature android:name="android.permission.MANAGE_EXTERNAL_STORAGE" android:required="false" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" android:maxSdkVersion="28" />
<uses-permission android:name="android.permission.READ_MEDIA_AUDIO" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.POST_NOTIFICATIONS"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="android.permission.VIBRATE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_MEDIA_IMAGES" />
<uses-permission android:name="android.permission.READ_MEDIA_VIDEO" />

Fragment.kt（关键代码） #

private fun initCamera() {
    cameraExecutor = Executors.newSingleThreadExecutor()
    requestCameraPermission()
}

private fun requestCameraPermission() {
    Dexter.withContext(requireContext())
        .withPermissions(
            Manifest.permission.RECORD_AUDIO,
            Manifest.permission.CAMERA
        ).withListener(object : MultiplePermissionsListener {
            override fun onPermissionsChecked(p0: MultiplePermissionsReport?) {
                p0?.let {
                    if (it.areAllPermissionsGranted()) {
                        startCamera(CameraSelector.DEFAULT_BACK_CAMERA)
                    }
                }
            }

            override fun onPermissionRationaleShouldBeShown(
                p0: MutableList<PermissionRequest>?,
                p1: PermissionToken?
            ) {
                p1?.continuePermissionRequest()
            }
        }).check()
}

private fun startCamera(cameraSelector: CameraSelector) {
    val cameraProviderFuture = ProcessCameraProvider.getInstance(requireContext())
    val cameraProvider: ProcessCameraProvider = cameraProviderFuture.get()

    cameraProviderFuture.addListener({
        // Preview配置
        val preview = Preview.Builder()
            .build()
            .also {
                binding.previewViewTalkerDuelCreateNewDuelTakeVideo.implementationMode =
                    PreviewView.ImplementationMode.COMPATIBLE
                it.setSurfaceProvider(
                    binding.previewViewTalkerDuelCreateNewDuelTakeVideo.surfaceProvider
                )
            }

        val recorder = Recorder.Builder()
            .setQualitySelector(
                QualitySelector.from(
                    Quality.HIGHEST,
                    FallbackStrategy.higherQualityOrLowerThan(Quality.SD)
                )
            )
            .build()

        videoCapture = VideoCapture.withOutput(recorder)

        try {
            cameraProvider.unbindAll()
            cameraProvider.bindToLifecycle(
                this, cameraSelector, preview, videoCapture
            )
        } catch (exc: Exception) {
            exc.printStackTrace()
        }
    }, ContextCompat.getMainExecutor(requireContext()))
}

Dexter版本 #

implementation 'com.karumi:dexter:6.2.3'

核心问题分析 #

1. 主线程阻塞导致Dexter权限流程中断
   startCamera方法中直接调用cameraProviderFuture.get()同步获取ProcessCameraProvider，会阻塞主线程（startCamera由权限回调触发，运行在主线程），导致主线程卡死，Dexter无法弹出权限弹窗、触发回调，表现为权限校验逻辑“未正常执行”。

2. AndroidManifest配置错误
   将MANAGE_EXTERNAL_STORAGE权限错误声明为<uses-feature>，该权限属于特殊权限，正确声明应为<uses-permission>，且Dexter不支持自动处理此类权限。

3. 存储权限覆盖不全（视频保存环节）
   API29-32（Android10-12）设备使用Scoped Storage，若需保存视频到公共目录，当前Manifest的权限配置不足，但这是视频保存问题，并非相机无法启动的直接原因。

修复步骤 #

1. 修复startCamera的线程阻塞问题 #

移除同步get()调用，将cameraProvider的获取放到addListener回调中，避免阻塞主线程：

private fun startCamera(cameraSelector: CameraSelector) {
    val cameraProviderFuture = ProcessCameraProvider.getInstance(requireContext())

    cameraProviderFuture.addListener({
        // 在回调中安全获取cameraProvider，此时Future已完成
        val cameraProvider: ProcessCameraProvider = cameraProviderFuture.get()

        // Preview配置
        val preview = Preview.Builder()
            .build()
            .also {
                binding.previewViewTalkerDuelCreateNewDuelTakeVideo.implementationMode =
                    PreviewView.ImplementationMode.COMPATIBLE
                it.setSurfaceProvider(
                    binding.previewViewTalkerDuelCreateNewDuelTakeVideo.surfaceProvider
                )
            }

        // Recorder配置
        val recorder = Recorder.Builder()
            .setQualitySelector(
                QualitySelector.from(
                    Quality.HIGHEST,
                    FallbackStrategy.higherQualityOrLowerThan(Quality.SD)
                )
            )
            .build()

        videoCapture = VideoCapture.withOutput(recorder)

        try {
            // 解绑旧用例再绑定新用例
            cameraProvider.unbindAll()
            cameraProvider.bindToLifecycle(
                this, cameraSelector, preview, videoCapture
            )
        } catch (exc: Exception) {
            exc.printStackTrace()
        }
    }, ContextCompat.getMainExecutor(requireContext()))
}

2. 修正AndroidManifest的权限声明错误 #

将错误的<uses-feature>改为<uses-permission>，并添加版本限制：

<!-- 替换错误的uses-feature声明 -->
<uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE" android:minSdkVersion="30" />

3. 确保Fragment生命周期正确调用initCamera #

在onViewCreated中调用initCamera()，确保Fragment已关联有效Context，Dexter能正常初始化权限请求：

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
    super.onViewCreated(view, savedInstanceState)
    initCamera()
}

4. 补充API29-32的存储权限处理（可选，针对视频保存） #

若需在API29-32设备保存视频到公共目录，需引导用户手动开启MANAGE_EXTERNAL_STORAGE权限：

private fun checkManageStoragePermission() {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R && !Environment.isExternalStorageManager()) {
        val intent = Intent(Settings.ACTION_MANAGE_APP_ALL_FILES_ACCESS_PERMISSION)
        intent.data = Uri.parse("package:${requireContext().packageName}")
        startActivity(intent)
    }
}

内容的提问来源于stack exchange，提问作者Ahmet Yılmaz