拍照，将其存储在内部存储中并在 Android (Kotlin) 上的活动中显示

Question

我正在尝试创建一个应用程序，其中用户拍摄保存在内部存储中的照片，然后在拍摄照片后，用户被带到另一个活动中的画廊，内部存储中的照片显示在回收者视图。

我已经完成了拍摄和存储照片的所有代码，但我不知道如何从存储中显示文件。

我知道我需要一个用于回收器视图的适配器，我可以这样做，而且我知道需要将文件放入一个类中才能这样做，但是我该如何编码才能提取文件显示在一个类中？抱歉，我对此非常陌生。

这是我的拍照和存储代码

import android.Manifest
import android.content.Intent
import android.content.pm.PackageManager
import android.icu.text.SimpleDateFormat
import android.net.Uri
import android.os.Build
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import android.widget.Toast
import androidx.annotation.RequiresApi
import androidx.camera.core.CameraSelector
import androidx.camera.core.ImageCapture
import androidx.camera.core.ImageCaptureException
import androidx.camera.core.Preview
import androidx.camera.lifecycle.ProcessCameraProvider
import androidx.core.app.ActivityCompat
import androidx.core.content.ContextCompat
import kotlinx.android.synthetic.main.activity_main.*
import java.io.File
import java.util.*
import java.util.concurrent.ExecutorService
import java.util.concurrent.Executors

class MainActivity : AppCompatActivity() {
    private var imageCapture: ImageCapture? = null

    private lateinit var outputDirectory: File
    private lateinit var cameraExecutor: ExecutorService

    private val TAG = "Snap"
    private val FILENAME_FORMAT = "yyyy-MM-dd-HH-mm-ss-SSS"
    private val REQUEST_CODE_PERMISSIONS = 10

    @RequiresApi(Build.VERSION_CODES.N)
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        btnSnap.setOnClickListener { takePhoto()}

        //request camera permissions
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) ==
            PackageManager.PERMISSION_GRANTED
        ) {
            startCamera()
        } else {
            ActivityCompat.requestPermissions(
                this,
                arrayOf(Manifest.permission.CAMERA), REQUEST_CODE_PERMISSIONS
            )
        }
        outputDirectory = getOutputDirectory()
        cameraExecutor = Executors.newSingleThreadExecutor()
    }

    override fun onRequestPermissionsResult(
        requestCode: Int,
        permissions: Array<String>, grantResults: IntArray
    ) {
        if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) ==
            PackageManager.PERMISSION_GRANTED
        ) {
            startCamera()

        } else {
            Toast.makeText(
                this, "Permissions not granted by the user",
                Toast.LENGTH_SHORT
            ).show()

        }
    }

    private fun startCamera() {
        val cameraProviderFuture = ProcessCameraProvider.getInstance(this)

        //add listener to the ProcessCameraProvider
        cameraProviderFuture.addListener(Runnable {
            val cameraProvider: ProcessCameraProvider = cameraProviderFuture.get()
            val preview = Preview.Builder().build().also {
                it.setSurfaceProvider(viewFinder.createSurfaceProvider())
            }

            imageCapture = ImageCapture.Builder().build()
            val cameraSelector = CameraSelector.DEFAULT_BACK_CAMERA

            try {
                //unbind use cases before rebinding
                cameraProvider.unbindAll()
                cameraProvider.bindToLifecycle(
                    this, cameraSelector, preview,
                    imageCapture
                )
            } catch (exc: Exception) {
                Log.e(TAG, "Use case binding failed", exc)
            }
        }, ContextCompat.getMainExecutor(this))
    }

    @RequiresApi(Build.VERSION_CODES.N)
    private fun takePhoto() {
        val imageCapture = imageCapture ?: return

        val photoFile = File(
            outputDirectory, SimpleDateFormat(
                FILENAME_FORMAT,
                Locale.UK
            ).format(System.currentTimeMillis()) + ".jpg"
        )

        val outputOpts = ImageCapture.OutputFileOptions.Builder(photoFile).build()

        imageCapture.takePicture(outputOpts,
            ContextCompat.getMainExecutor(this), object :
                ImageCapture.OnImageSavedCallback {
                override fun onError(exc: ImageCaptureException) {
                    Log.e(TAG, "Photo capture failed: ${exc.message}", exc)
                }

                //save the photo to the file and display on screen
                override fun onImageSaved(output: ImageCapture.OutputFileResults) {
                    val savedUri = Uri.fromFile(photoFile)
                    imgSnap.setImageURI(savedUri)
                    
                }
            })
    }

    private fun getOutputDirectory(): File {
        val mediaDir = externalMediaDirs.firstOrNull()?.let {
            File(it, resources.getString(R.string.app_name)).apply {
                mkdirs()

            }
        }
        return if (mediaDir != null && mediaDir.exists()) mediaDir else filesDir
    }
    

}