Question

我想首先选择pdf文件，然后将其编码为base64并将其保存到共享首选项。之后，解码并保存为pdf。并打开该pdf进行查看。

打开时会显示消息“无法打开此文档”。看起来编码/解码部分存在一些问题。我不知道在哪里。所以，如果有人对此有所了解，那对我来说将是非常有帮助的。谢谢，

我的代码如下：

编码：

public static String getBase64Pdf(String pdfFilePath){
    try{
        InputStream inputStream = new FileInputStream(pdfFilePath);
        byte[] byteArray = IOUtils.toByteArray(inputStream);
        String encodedPdfString = Base64.encodeToString(byteArray, Base64.DEFAULT);
        PrintLog.showTag(TAG,"pdf converted to string : " + encodedPdfString);
        return encodedPdfString;
    }catch (IOException e){
    }
    return "";
}

解码，保存到文件并打开pdf：

private void openPdfViewer(){
    try{
        PrintLog.showTag(TAG,"== opnPdfViewer & length of base64 string is =="
                + sessionManager.getBase64ProofImage().length());

        //== decode and write file here
        String base64pdf = sessionManager.getBase64ProofImage();//gets base64 from shared preference
        final File newFilePath = new File(getActivity().getFilesDir(), "warrantyProof.pdf");
        byte[] pdfAsBytes = Base64.decode(base64pdf, Base64.NO_WRAP);
        FileOutputStream os;
        os = new FileOutputStream(newFilePath, false);
        os.write(pdfAsBytes);
        os.flush();
        os.close();

        //==== open pdf file here
        File file = new File(getActivity().getFilesDir(),"warrantyProof.pdf");

        Intent intent = new Intent(Intent.ACTION_VIEW);
        intent.setDataAndType(Uri.fromFile(file), "application/pdf");
        intent.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
        startActivity(intent);
    }catch (IOException e){
        PrintLog.showException(TAG,"IO exception saving pdf ",e);
    }
    catch (Exception e){
        PrintLog.showException(TAG,"exception opening pdf",e);
    }
}

Answer 1

 File dir = Environment.getExternalStorageDirectory();
    File yourFile = new File(dir, "path/to/the/file/inside/the/myfile.ext");
    String encodeFileToBase64Binary = encodeFileToBase64Binary(yourFile);

    private static String encodeFileToBase64Binary(File fileName) throws IOException {
          byte[] bytes = loadFile(fileName);
          byte[] encoded = Base64.encodeBase64(bytes);
          String encodedString = new String(encoded);
          return encodedString;
     }

Android：将pdf编码为base64＆amp;解码回pdf会显示“此文档无法打开”

1 个答案: