Android WebView Dosya İndirme ve Manifest İzinleri Verme

Android WebView Dosya İndirme ve Manifest İzinleri Verme

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

Java Class
public class MainActivity extends AppCompatActivity {
     WebView webView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        webView = (WebView) findViewById(R.id.webView);
        webView.getSettings().setJavaScriptEnabled(true);
        webView.loadUrl("http://www.caglayangrup.com.tr/carigiris.aspx");
        webView.setWebViewClient(new WebViewClient());


        webView.setDownloadListener(new DownloadListener() {
            @Override
            public void onDownloadStart(String url, String userAgent, String contentDisposition, String mimetype, long contentLength) {
                DownloadManager.Request request = new DownloadManager.Request(Uri.parse(url));

                request.setDescription("Download file...");
                request.setTitle(URLUtil.guessFileName(url, contentDisposition, mimetype));
                request.allowScanningByMediaScanner();
                request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED); //Notify client once download is completed!
                request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, URLUtil.guessFileName(url, contentDisposition, mimetype));
                DownloadManager dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
                dm.enqueue(request);
                Toast.makeText(getApplicationContext(), "E-Arşiv Faturası İndiriliyor..", Toast.LENGTH_LONG).show();
            }
        });

    }