下载文件并保存在安卓版本高于5的应用程序文件夹中(lolipop)

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

File directory = getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS);
if (directory != null) {
    String path = directory.getAbsolutePath();
}

DownloadManager.Request request = new DownloadManager.Request(Uri.parse(url));
request.setDestinationInExternalFilesDir(this, Environment.DIRECTORY_DOWNLOADS, fileName);
DownloadManager manager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);
long downloadId = manager.enqueue(request);

import android.Manifest;
import android.content.pm.PackageManager;
import android.net.Uri;
import android.os.Environment;
import android.os.Handler;
import android.os.Looper;
import android.widget.Toast;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import java.io.File;

public class DownloadActivity extends AppCompatActivity {
    private static final int REQUEST_CODE = 123;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_download);

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

    private void startDownload() {
        String url = "https://example.com/file.zip";
        String fileName = "file.zip";
        File directory = getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS);
        if (directory != null) {
            Uri uri = Uri.parse(url);
            DownloadManager.Request request = new DownloadManager.Request(uri);
            request.setDestinationInExternalFilesDir(this, Environment.DIRECTORY_DOWNLOADS, fileName);
            DownloadManager manager = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
            long downloadId = manager.enqueue(request);

            new Handler(Looper.getMainLooper()).postDelayed(() -> {
                Toast.makeText(this, "Download completed", Toast.LENGTH_SHORT).show();
            }, 5000); // Simulate download completion
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        if (requestCode == REQUEST_CODE) {
            if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                startDownload();
            } else {
                Toast.makeText(this, "Permission denied", Toast.LENGTH_SHORT).show();
            }
        }
    }
}