在PrintDocumentAdapter中使用字节数组打印受密码保护的Pdf

Question

我尝试直接打印文件，但是它不起作用，因此我从url下载了pdf文件，并将其保存在本地目录中，然后尝试在其上应用“打印文档适配器”，但同时也会引发无法打印受密码保护的Pdf的错误。我尝试在加载到Webview后打印它，但是它只打印屏幕上显示的内容，而不打印Webview中加载的整个URL。是否有任何方法可以打印受密码保护的pdf文档？使用此代码可以完美地打印没有密码保护的PDF。 >

MyActivity

class DownloadTask extends AsyncTask<String, Integer, String> {

        private Context context;

        public DownloadTask(Context context) {
            this.context = context;
        }

        @Override
        protected String doInBackground(String... sUrl) {

            InputStream input = null;
            OutputStream output = null;
            HttpURLConnection connection = null;

            try {
                File pdfTempDir = new File(PreviewPdfActivity.this.getFilesDir().getAbsolutePath() + File.separator + "PDFPrint");
                if (!pdfTempDir.exists()) {
                    pdfTempDir.mkdir();
                }

                fileTemp = new File(pdfTempDir, filePath);


                URL url = new URL(sUrl[0]);
                connection = (HttpURLConnection) url.openConnection();
                connection.connect();

                // expect HTTP 200 OK, so we don't mistakenly save error report
                // instead of the file
                if (connection.getResponseCode() != HttpURLConnection.HTTP_OK) {
                    return "Server returned HTTP " + connection.getResponseCode()
                            + " " + connection.getResponseMessage();
                }

                // this will be useful to display download percentage
                // might be -1: server did not report the length
                int fileLength = connection.getContentLength();

                // download the file
                input = connection.getInputStream();

                output = new FileOutputStream(fileTemp, true);

                byte data[] = new byte[4096];
                long total = 0;
                int count;
                while ((count = input.read(data)) != -1) {
                    // allow canceling with back button


                    if (!downloadTask.isCancelled()) {
                        total += count;
                        // publishing the progress....
                        if (fileLength > 0) {
                            // only if total length is known
                            publishProgress((int) (total * 100 / fileLength));
                        }

                        output.write(data, 0, count);
                    }

                }


            } catch (Exception e) {
                return e.toString();
            } finally {
                try {
                    if (output != null)
                        output.close();
                    if (input != null)
                        input.close();
                } catch (IOException ignored) {
                }

                if (connection != null)
                    connection.disconnect();
            }
            return null;
        }


        @TargetApi(Build.VERSION_CODES.KITKAT)
        @Override
        protected void onPostExecute(String result) {
            if (result != null)
                Toast.makeText(context, "Download error: " + result, Toast.LENGTH_LONG).show();
            else {

                if(fileTemp.exists())
                {

                    PrintDocumentAdapter pda = new PrintDocumentAdapter(){

                        @Override
                        public void onWrite(PageRange[] pages, ParcelFileDescriptor destination, CancellationSignal cancellationSignal, WriteResultCallback callback){
                            InputStream input = null;
                            OutputStream output = null;

                            try {

                                input = new FileInputStream(fileTemp);
                                output = new FileOutputStream(destination.getFileDescriptor());

                                byte[] buf = new byte[1024];
                                int bytesRead;

                                while ((bytesRead = input.read(buf)) > 0) {
                                    output.write(buf, 0, bytesRead);
                                }

                                callback.onWriteFinished(new PageRange[]{PageRange.ALL_PAGES});

                            } catch (FileNotFoundException ee){
                                //Catch exception
                            } catch (Exception e) {
                                //Catch exception
                            } finally {
                                try {
                                    input.close();
                                    output.close();
                                } catch (IOException e) {
                                    e.printStackTrace();
                                }
                            }
                        }

                        @Override
                        public void onLayout(PrintAttributes oldAttributes, PrintAttributes newAttributes, CancellationSignal cancellationSignal, LayoutResultCallback callback, Bundle extras){

                            if (cancellationSignal.isCanceled()) {
                                callback.onLayoutCancelled();
                                return;
                            }


                            PrintDocumentInfo pdi = new PrintDocumentInfo.Builder("Name of file").setContentType(PrintDocumentInfo.CONTENT_TYPE_DOCUMENT).build();

                            callback.onLayoutFinished(pdi, true);
                        }
                    };

                    PrintManager printManager = (PrintManager) PreviewPdfActivity.this.getSystemService(Context.PRINT_SERVICE);
                    String jobName = getString(R.string.app_name) + " Document";
                    printManager.print(jobName, pda, null);


                }

            }

        }

    }