Android requestPermissionLauncher不显示权限对话框

因此，我尝试使用新的权限请求方式（允许系统管理权限请求代码），如本文所述。当我点击相机按钮时，我得到的只是“权限被拒绝”，但我没有得到一个包含实际权限请求的窗口（在这里我可以允许或拒绝它）。在文档中写着“若要在必要时显示系统权限对话框，请在上一步中保存的ActivityResultLauncher实例上调用launch（）方法。”？我错过了什么

在onViewCreated下，我有：

binding.camera.setOnClickListener{
        when {
            ContextCompat.checkSelfPermission(
                    requireContext(),
                    Manifest.permission.CAMERA
            ) == PackageManager.PERMISSION_GRANTED -> {
                // You can use the API that requires the permission.
                //startCamera()
                makeText(activity, "Start camera", LENGTH_SHORT).show()
            }
            shouldShowRequestPermissionRationale(Manifest.permission.CAMERA) -> {
                // In an educational UI, explain to the user why your app requires this
                // permission for a specific feature to behave as expected. In this UI,
                // include a "cancel" or "no thanks" button that allows the user to
                // continue using your app without granting the permission.
                makeText(activity, "Camera is necessary to add content.", LENGTH_SHORT).show()
            }
            else -> {
                    // You can directly ask for the permission.
                    // The registered ActivityResultCallback gets the result of this request.
                    requestPermissionLauncher.launch(
                                    Manifest.permission.CAMERA)
                }
            }
    }  

我有一段代码：

// Permission
val requestPermissionLauncher = registerForActivityResult(ActivityResultContracts.RequestPermission()) {
    isGranted: Boolean -> if (isGranted){
        // Permission Accepted
        makeText(activity, "Permission Accepted.", LENGTH_SHORT).show()
    }
    else {
        // Permission Denied
        makeText(activity, "Permission Denied.", LENGTH_SHORT).show()
    }
}

---

如果您在Android 10（API 29）上运行，请在清单中添加以下行：

android:requestLegacyExternalStorage="true"

---

如果您在Android 10（API 29）上运行，请在清单中添加以下行：

android:requestLegacyExternalStorage="true"

---

你能在else->ActivityCompat.requestPermissions（此处需要摄像头请求）之后再试吗？我总是写这段代码，它可以工作。然后检查清单文件。你添加了权限了吗？也许你忘了在清单文件中请求权限了。你能在else->ActivityCompat.requestPermissions（此处需要摄像头请求）之后再试吗我总是写这段代码，它可以工作。试试这个。检查清单文件你添加了权限了吗？也许你忘了在清单文件中请求它