AndroidManifest.xml

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

MainActivity.kt

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        if (ContextCompat.checkSelfPermission(
                this@MainActivity,
                Manifest.permission.WRITE_EXTERNAL_STORAGE
            ) != PackageManager.PERMISSION_GRANTED
        ) {
            ActivityCompat.requestPermissions(
                this@MainActivity,
                arrayOf(Manifest.permission.WRITE_EXTERNAL_STORAGE),
                1
            )
        }
    }

    override fun onRequestPermissionsResult(
        requestCode: Int,
        permissions: Array<String?>,
        grantResults: IntArray
    ) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults)
        when (requestCode) {
            1 -> if (grantResults.isNotEmpty() && grantResults[0] != PackageManager.PERMISSION_GRANTED) {
                Toast.makeText(this, "拒绝权限将无法使用程序", Toast.LENGTH_SHORT).show()
                finish()
            }
            else -> {}
        }
    }
}