How to increase download speed using the following method?

Question

I have written an Android application which downloads pdf files through web service. I am using kSoap2 android library to parse the response of web service which basically contains file name & file data.

I have written following code. Please review & tell how to increase the speed I think there is some small defect in code which reduces the speed. I am using version 2.5.1 of kSoap2.

public void downloadPdfFiles(File fileDocsDir, int noOfFiles)
            throws NullPointerException, SoapFault, XmlPullParserException,
            FileNotFoundException, IOException, Exception {

        System.gc();

        // Download files from web service and save them in the folder.
        soapObject = new SoapObject(NAMESPACE, METHOD_NAME);
        soapObject.addProperty("startingFile", noOfFiles);
        soapObject.addProperty("deviceId", deviceId);
        soapObject.addProperty("loginId", loginId);
        soapObject.addProperty("byoinId", "1");

        envelope = new SoapSerializationEnvelope(SoapEnvelope.VER11);

        envelope.setOutputSoapObject(soapObject);

        // Calling the web service
        System.gc();
        androidHttpTransport = new HttpTransportSE(URL);
        androidHttpTransport.call(SOAP_ACTION, envelope);

        // Getting Response through xml mainly generated as soap:reponse.
        responseBean = (SoapObject) envelope.getResponse();

        // Array of PDFInfoBean.
        list = (SoapObject) responseBean.getProperty(0);

        FileOutputStream outputStream = null;
        BufferedOutputStream bufferedOutputStream = null;
        // Get Individual PDF Details from Array.
        SoapObject pdfDetails = null;

        mIncrement = noOfFiles;
        // Log.i("Increment Values", String.valueOf(mIncrement));

        File pdfFile = null;
        for (int i = 0; i < list.getPropertyCount(); i++) {
            pdfDetails = (SoapObject) list.getProperty(i);

            // Get PDF File Name.
            pdfDocName = pdfDetails.getProperty(1).toString();
            Log.i(TAG, "File Name: " + pdfDocName);

            // Check for last file.
            if (pdfDocName.equalsIgnoreCase("EOF")) {
                mFlag = false;
                break;
            }

            // Creating PDF File.
            pdfFile = new File(fileDocsDir, pdfDocName);

            // Writing PDF file received through web service.
            if (pdfFile.exists()) {
                Log.i(TAG, pdfFile.getName() + " File Already Exists");
            } else {
                outputStream = new FileOutputStream(pdfFile);
                bufferedOutputStream = new BufferedOutputStream(outputStream);

                bufferedOutputStream.write(Base64Coder.decode(pdfDetails
                        .getProperty(0).toString()));

                mIncrement = mIncrement + 1;

                bufferedOutputStream.close();
                outputStream.close();

                bufferedOutputStream = null;
                outputStream = null;
            }
            pdfDetails = null;
            pdfDocName = null;
            pdfFile = null;
            System.gc();
        }
        soapObject = null;
        envelope = null;
        responseBean = null;
        list = null;
        androidHttpTransport = null;

        System.gc();
    }

Answer 1

1. Forcing System.gc() isn't a good practice.

2. outputStream = new FileOutputStream(pdfFile);
           bufferedOutputStream = new BufferedOutputStream(outputStream);
   

   should be wrapped into 1 variable to do a single close() afterwards:

   outputStream = new BufferedOutputStream(new FileOutputStream(pdfFile));
   

3. All operations with outputStream should be put in try-finally block:

   outputStream = new ...
   try {
       outputStream.write(...);
       ...
   } finally {
       outputStream.close();
   }
   

4. Agree with the first comment: your file may simply not fit in memory. In SOAP API there should be some mean of getting the InputStream instead of an in-memory string.

Sorry for the formatting, couldn't fight the editor.

Good luck!

Answer 2

@weekens noted:

Forcing System.gc() isn't a good practice.

This is so true. In fact, calling System.gc() is likely to have a major impact on the performance of your application.