Read an inputstream and download using DownloadManager

问题

I am trying to download and save the file to sd card. The file url is as follows

http://test.com/net/Webexecute.aspx?fileId=120

This url provides a stream of data. I have the following option to read the input stream.

• Use generic input and output stream (no handlers for connection fail overs)

• Download manager

• Using HttpUrlConnection (possible timeout chances)

I have done the download using option a. But there are no handlers for connection fail overs. So I decided to go with option b

DownloadManager dm = (DownloadManager) context.getSystemService(Context.DOWNLOAD_SERVICE);
Request request = new Request(Uri.parse("http://test.com/net/Webexecute.aspx?fileId="+ fileId));
request.setMimeType("application/pdf");
request.setDescription("fileDownload");
request.setTitle(fileName);
request.setNotificationVisibility(Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
dm.enqueue(request);

It is downloading the file. However, the file seems to be corrupted.

While doing the research, I never found DownloadManager being used to fetch an input stream and save that to a file. Is there anything I am lacking?

回答1:

Please change your code to download a file.

protected Void downLoadFile(String fileURL) {

    int count;
    try
    {

        URL url = new URL(fileURL);
        URLConnection conexion = url.openConnection();
        conexion.connect();
        int lenghtOfFile = conexion.getContentLength();
        InputStream is = url.openStream();

        File testDirectory = new File(Environment.getExternalStorageDirectory() + "/Download");
        if (!testDirectory.exists())
        {
            testDirectory.mkdir();
        }

        FileOutputStream fos = new FileOutputStream(testDirectory + "/filename.txt");


        byte data[] = new byte[1024];
        long total = 0;
        int progress = 0;
        while ((count = is.read(data)) != -1)
        {
            total += count;
            int progress_temp = (int) total * 100 / lenghtOfFile;

            fos.write(data, 0, count);

        }
        is.close();
        fos.close();

        readStringFromFile(testDirectory);

    }
    catch (Exception e)
    {
        Log.e("ERROR DOWNLOADING", "Unable to download" + e.getMessage());
        e.printStackTrace();
    }
    return null;

The Below method is used to read string from file.

public String readStringFromFile(File file){
        String response="";
        try
        {
            FileInputStream fileInputStream= new FileInputStream(file+"/filename.txt");
            StringBuilder builder = new StringBuilder();
            int ch;
            while((ch = fileInputStream.read()) != -1){
                builder.append((char)ch);
            }
            response = builder.toString();

        }
        catch (FileNotFoundException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        catch (IOException e)
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return response;
    }

Let me know of you still face any issue..

Thanks

来源：https://stackoverflow.com/questions/24137071/read-an-inputstream-and-download-using-downloadmanager