Android-我从服务器获取Json响应为PDF（或）JPG（或）PNG文件。如何处理视图（或）按用户下载

Question

我在用

http连接方法：获取

请求/响应：JSON

我有一些带有ID的记录（参见下图） 。 用户单击记录时。 我正在使用单击的记录ID向服务器调用HttpConnection（JSON请求）。

Json请求网址： http://xyz.in/api/mobile/document/12345/{record Id} ： http://xyz.in/api/mobile/document/12345/{record Id}

我从服务器获取Json Response作为PDF（或）JPG（或）PNG的地方。

Json回应：

%PDF-1.5

%����

1 0 obj

<</Type/Catalog/Pages 2 0 R/Lang(en-US) /StructTreeRoot 51 0 R/MarkInfo<</Marked true>>>>

endobj

2 0 obj

<</Type/Pages/Count 11/Kids[ 3 0 R 10 0 R 18 0 R 21 0 R 24 0 R 27 0 R 30 0 R 33 0 R 36 0 R 39 0 R 47 0 R] >>

endobj

3 0 obj

<</Type/Page/Parent 2 0 R/Resources<</ExtGState<</GS5 5 0 R/GS6 6 0 R>>/Font<</F1 7 0 R>>/XObject<</Image9 9 0 R>>/ProcSet[/PDF/Text/ImageB/ImageC/ImageI] >>/MediaBox[ 0 0 960 540] /Contents 4 0 R/Group<</Type/Group/S/Transparency/CS/DeviceRGB>>/Tabs/S/StructParents 0>>

endobj

4 0 obj

<</Filter/FlateDecode/Length 340>>

stream

x���Mk1����9�
fg&������ҥ=��U)T����MV[?.�fC��ɛY(��j���nC�ׅ)P!"1���!X���J�؀������S
���at����5�����.���$Tl)��˸6�����J��u:j�{µyGa�4�iuW�Gj0I?�U��u
�S��k4Z��N�7�T�T�Y��)�QY�b&�@��l��Ͼsr�{��R��?Cu+E�����g���9|�(͊Ϣ��r�­�)�e��5���R�N䬳q��oϥ�m6ټ����<��<47�=��sH�?��e�v��+����K�.���|ZBo��߶�

endstream

endobj

如果我在Android Webview中加载该URL（ http://xyz.in/api/mobile/document/12345/ {record Id}），那么响应是PDF，我可以查看它。 但回应是JPG或PNG。 它无法在Webview中查看。

如何处理它以供Android用户查看（或）下载。

提前致谢。

Answer 1

//Calling the Download file (Asynctask class). 
new DownloadFileFromURL().execute(DownloadFileUrl);



//Progress dialog for download url
    protected Dialog onCreateDialog(int id) {
        switch (id) {
            case progress_bar_type: // we set this to 0
                pDialog = new ProgressDialog(this);
                pDialog.setMessage("Downloading file. Please wait...");
                pDialog.setIndeterminate(false);
                pDialog.setMax(100);
                pDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
                pDialog.setCancelable(true);
                pDialog.show();
                return pDialog;
            default:
                return null;
        }
    }

    /**
     * Background Async Task to download file
     */
    class DownloadFileFromURL extends AsyncTask<String, String, String> {
        String filename="";
        /**
         * Before starting background thread
         * Show Progress Bar Dialog
         */
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            showDialog(progress_bar_type);
        }

        /**
         * Downloading file in background thread
         */
        @Override
        protected String doInBackground(String... f_url) {
            int count;
            try {
                URL url = new URL(f_url[0]);
                URLConnection conection = url.openConnection();
                conection.connect();
                // this will be useful so that you can show a tipical 0-100% progress bar
                int lenghtOfFile = conection.getContentLength();
                String depo = conection.getHeaderField("Content-Disposition");
                String depoSplit[] = depo.split("filename=");
                filename = depoSplit[1].replace("filename=", "").replace("\"", "").trim();
                Log.v("","fileName"+filename);

                // download the file
                InputStream input = new BufferedInputStream(url.openStream(), 8192);

                // Output stream
                OutputStream output = new FileOutputStream("/sdcard/"+filename);

                byte data[] = new byte[1024];

                long total = 0;

                while ((count = input.read(data)) != -1) {
                    total += count;
                    // publishing the progress....
                    // After this onProgressUpdate will be called
                    publishProgress("" + (int) ((total * 100) / lenghtOfFile));

                    // writing data to file
                    output.write(data, 0, count);
                }

                // flushing output
                output.flush();

                // closing streams
                output.close();
                input.close();

            } catch (Exception e) {
                Log.e("Error: ", e.getMessage());
            }

            return null;
        }

        /**
         * Updating progress bar
         */
        protected void onProgressUpdate(String... progress) {
            // setting progress percentage
            pDialog.setProgress(Integer.parseInt(progress[0]));
        }

        /**
         * After completing background task
         * Dismiss the progress dialog
         **/
        @Override
        protected void onPostExecute(String file_url) {
            // dismiss the dialog after the file was downloaded
            dismissDialog(progress_bar_type);

            // Reading filepath from sdcard
            String FilePath = Environment.getExternalStorageDirectory().toString() + "/"+filename;

            Log.v("FilePath", "" + FilePath);
        }

    }

Answer 2

好的，你得到的不是json，它是一个流。 并使用保存它

try {
    //input is your input stream object
    File file = new File(Environment.getExternalStorageDirectory(), "filename.pdf");
    OutputStream output = new FileOutputStream(file);
    try {
        try {
            byte[] buffer = new byte[4 * 1024]; // or other buffer size
            int read;

            while ((read = input.read(buffer)) != -1) {
                output.write(buffer, 0, read);
            }
            output.flush();
        } finally {
            output.close();
        }
    } catch (Exception e) {
        e.printStackTrace(); // handle exception, define IOException and others
    }
} finally {
    input.close();
}

Answer 3

虽然我喜欢@insomniac的回答，但我更喜欢使用更简单的方法来保存文件流，这应该从URL读取。

public void DownloadFromUrl(String url, String, dir String fileName) {
    try {
        URL url = new URL(url); //you can write here any link
        File file = new File(dir, fileName);
        URLConnection ucon = url.openConnection();
        InputStream is = ucon.getInputStream();
        BufferedInputStream bis = new BufferedInputStream(is);
        ByteArrayBuffer baf = new ByteArrayBuffer(5000);
        int current = 0;
        while ((current = bis.read()) != -1) {
            baf.append((byte) current);
        }
        FileOutputStream fos = new FileOutputStream(file);
        fos.write(baf.toByteArray());
        fos.flush();
        fos.close();
    } catch (IOException e) {
    }
}

请记住添加权限

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>
<uses-permission android:name="android.permission.INTERNET"></uses-permission>