Android在WebView中调用系统下载的方法

class MyDownloadStart implements DownloadListener{
  @Override
  public void onDownloadStart(String url, String userAgent, String contentDisposition, String mimetype, long contentLength) {
   downUrl = url;
   //从链接里获取文件名
   String dirNameString = url.substring(url.lastIndexOf("/") + 1);
   //获得下载文件的大小
   DecimalFormat decimalFormat = new DecimalFormat("0.00");
   float size = contentLength;
   dirName.setText(dirNameString);
   if (size <1024){
    dirSize.setText(size + "B");
   }else if (size <1048576){
    String dirSizeStringKB = decimalFormat.format(size / 1024);
    dirSize.setText(dirSizeStringKB + "K");
   }else if (size <1073741824){
    String dirSizeString = decimalFormat.format(size / 1048576);
    dirSize.setText(dirSizeString + "M");
   }else {
    String dirStringG = decimalFormat.format(size / 1073741824);
    dirSize.setText(dirStringG + "G");
   }
   //显示是否下载的dialog
   downdialog.show();
  }
}

mWebView.setWebViewDownListener(new MyDownloadStart());

DownloadManager downloadManager = (DownloadManager) getContext().getSystemService(Context.DOWNLOAD_SERVICE);
DownloadManager.Request request = new DownloadManager.Request(Uri.parse(downUrl));
//下载时，下载完成后显示通知
request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
//下载的路径，第一个参数是文件夹名称，第二个参数是下载的文件名
request.setDestinationInExternalPublicDir("SooDown",dirName.getText().toString());
request.setVisibleInDownloadsUi(true);
downloadManager.enqueue(request);

public class DownloadReceiver extends BroadcastReceiver{


 @Override
 public void onReceive(Context context, Intent intent) {
  DownloadManager manager = (DownloadManager) context.getSystemService(Context.DOWNLOAD_SERVICE);
  if (DownloadManager.ACTION_DOWNLOAD_COMPLETE.equals(intent.getAction())){
   Toast.makeText(context,"下载完成",Toast.LENGTH_SHORT).show();
  }else if (DownloadManager.ACTION_NOTIFICATION_CLICKED.equals(intent.getAction())){
   //点击通知栏进入下载管理页面
   Intent intent1 = new Intent(DownloadManager.ACTION_VIEW_DOWNLOADS);
   intent1.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
   context.startActivity(intent1);
  }
 }
}