文件是部分从Webview Android下载的

Question

I getting issue while downloading a PDF file on click of button click in webview.

File is downloaded but the file is partly downloaded that's why i am getting below error

"The document cannot be opened because it is not a valid PDF document"

Below is Asyncetask activity of my to download file:

 public class DownloadPDFTask extends AsyncTask<String, Void, Integer> 
     {
         protected ProgressDialog mWorkingDialog;    // progress dialog
         protected String mFileName;         // downloaded file
         protected String mError;            // for errors

         @Override
         protected Integer doInBackground(String... urls)
         {
             String filename = "";
             String str[] =  urls[2].split(";");
             String st[] =str[1].split("=");
             filename = st[1];
             String extStorageDirectory = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).toString();
                File myDir = new File(extStorageDirectory, "NCR");

                File file = new File(extStorageDirectory+"/NCR/"+filename);     
                    // create the directory if it does not exist
                    if (!myDir.exists()) 
                        myDir.mkdirs();  

                    if (file.exists()) {
                        System.out.println("INSIDE FILE EXIST");
                        file.delete();
                    }
          try
          {
           byte[] dataBuffer = new byte[4096];
               int nRead = 0;

               mFileName = filename;

               System.out.println("mFileName<><><> " +mFileName);
               // download URL and store to strFileName

               // connection to url
               java.net.URL urlReport = new java.net.URL(urls[0]);
               URLConnection urlConn = urlReport.openConnection();
               urlConn.setRequestProperty("User-Agent", urls[1]);
               urlConn.setRequestProperty("Content-Disposition", urls[2]); 
               urlConn.setRequestProperty("Content-Type", "application/pdf"); 
               urlConn.setRequestProperty("Accept", "*/*"); 
               InputStream streamInput = urlReport.openStream();
               BufferedInputStream bufferedStreamInput = new BufferedInputStream(streamInput,8192);
               FileOutputStream outputStream = new FileOutputStream(extStorageDirectory+"/NCR/"+mFileName);
               while ((nRead = bufferedStreamInput.read(dataBuffer)) > 0)
                     outputStream.write(dataBuffer, 0, nRead);
               streamInput.close();
               outputStream.close();
//             displayPdf(mFileName);

           }
           catch (Exception e)
           {
            Log.e("myApp", e.getMessage());
            mError = e.getMessage();
            return (1);
           }

          return (0);
         }



         @Override
         protected void onPreExecute()
         {
          // show "Downloading, Please Wait" dialog
          mWorkingDialog = ProgressDialog.show(context, "", "Downloading PDF Document, Please Wait...", true);
          return;
         }



         @Override
         protected void onPostExecute (Integer result)
         {
              if (mWorkingDialog != null)
           {
            mWorkingDialog.dismiss();
            mWorkingDialog = null;
           }

              switch (result)
              {
              case 0:                            // a URL
                 try
                 {

                     displayPdf(mFileName);
                 }
                 catch (ActivityNotFoundException e)
                 {
                     Toast.makeText(context, "No PDF Viewer Installed", Toast.LENGTH_LONG).show();
                 }

                 break;

             case 1:                         // Error

                 Toast.makeText(context, mError, Toast.LENGTH_LONG).show();
                 break;

             }

         }

     }

Friends I am stuck on this, Please help me out.

Answer 1

Hope this will help you. I tested this code and this is working fine.

@Override
        protected String doInBackground(String... params) {
            // TODO Auto-generated method stub
            int count;
            try{
                URL url=new URL(params[0]);
                URLConnection connection=url.openConnection();
                connection.connect();
                //getting file length
                long lengthOfFile=connection.getContentLength();
                //input stream to read file with 8k buffer
                InputStream input=new BufferedInputStream(url.openStream(),8192);
                //out stream to write file
                OutputStream output=new FileOutputStream(Environment.getExternalStorageDirectory()+"/Download/Test/software_testing.pdf");

                byte data[]= new byte[1024];
                long total =0;
                while ((count = input.read(data)) != -1){
                    if(isCancelled())
                        return null;
                    total +=count;
                    //publishing the progress
                    //After this onProgressUpdate will be called
                    if(lengthOfFile > 0){
                        //System.out.println((int)((total*100)/lengthOfFile)+"First Line");
                        //Call onProgressUpdate() for display status
                        publishProgress((int)((total*100)/lengthOfFile));

                    }

                    //writing data to file
                    output.write(data,0,count);
                } 
                //flushing output
                output.flush();
                //closing stream
                output.close();
                input.close();

            }catch(Exception e){
                Log.e("Error", e.getMessage());
                System.out.println("Exception :"+e.getMessage());
            }

            return null;

        }

EDITED:

Extend your class from AsyncTask<String, Integer, String> and override its' methods. `

• onPreExecute() used to do process before start the download.
• doInBackground(String... params) used to do the process while downloading the file. The above code is for this method.

• onProgressUpdate(Integer... progress) used to do setting the progress bar according to the current download percentage. Once you use publishProgress (), this method will invoke.

• onPostExecute(String file_url) This method can used to dismiss the dislog after the file was downloaded.

So what you have to do is set your progress bar to update according to the downloading percentage inside onProgressUpdate (Integer... progress) . You can use setProgress() method for that.

I hope now you understand the process well :)

Answer 2

This might not be an issue, but your while loop isn't correct:

while ((nRead = bufferedStreamInput.read(dataBuffer)) > 0)
                     outputStream.write(dataBuffer, 0, nRead);

The BufferedInputStream.read() returns a -1 when it reaches the end of the stream.

Rather, your terminating condition should be:

while ((nRead = bufferedStreamInput.read(dataBuffer)) != -1)
                     outputStream.write(dataBuffer, 0, nRead);

I hope this helps.