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();
 }

• Ron: what are the sizes of these pdf's? you're buffering the entire things in memory before writing them out; I suspect even without your System.gc's to spice things up, you observe lots of gc activity and possibly OOME's.
• Shashank_Itmaster: Basically the size of pdf's that are to be received at client side are of 1 mb from 533mb folder at server side.
• user11721: can you post server side web service code also. Thanks Sampath

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!

• Shashank_Itmaster: Thanks for your answer.I already overcome the problem of OutOfMemory issue,here I posted it for just get better review from sharp programmers.
• Landei: I agree with 3., but it should be mentioned that if Java 7 is available, ARM-blocks can deal with that pain.
• Adam: @Landei also known as try-with-resources.

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.