Android写二级外部存储(权限被拒绝)

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

if (ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
    ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, REQUEST_CODE);
}

@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
    if (requestCode == REQUEST_CODE) {
        if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
            // 权限被授予，可以进行外部存储的写入操作
        } else {
            // 权限被拒绝，无法进行外部存储的写入操作
        }
    }
}

File externalFilesDir = getExternalFilesDir(null);
if (externalFilesDir != null) {
    File subDirectory = new File(externalFilesDir, "sub_directory");
    if (!subDirectory.exists()) {
        subDirectory.mkdirs();
    }
    // 在sub_directory目录下进行写入操作
}