Develop Reference

Android : How to pause and resume Download using HttpUrlConnection?

I want to make a download manager for android I want to know how can I add
pause and resume functionality I am using HttpUrlConnection class of android
for getting the data.I also want to know how can I access the InputStream which I get from HttpUrlConnection.getInputStream() which get Interrupted because of the Internet connection(say user turn off internet connection).
any sample code will be helpful

Downloader example here
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
if(ISSUE_DOWNLOAD_STATUS.intValue()==ECMConstant.ECM_DOWNLOADING){
File file=new File(DESTINATION_PATH);
if(file.exists()){
downloaded = (int) file.length();
connection.setRequestProperty("Range", "bytes="+(file.length())+"-");
}
}else{
connection.setRequestProperty("Range", "bytes=" + downloaded + "-");
}
connection.setDoInput(true);
connection.setDoOutput(true);
progressBar.setMax(connection.getContentLength());
in = new BufferedInputStream(connection.getInputStream());
fos=(downloaded==0)? new FileOutputStream(DESTINATION_PATH): new FileOutputStream(DESTINATION_PATH,true);
bout = new BufferedOutputStream(fos, 1024);
byte[] data = new byte[1024];
int x = 0;
while ((x = in.read(data, 0, 1024)) >= 0) {
bout.write(data, 0, x);
downloaded += x;
progressBar.setProgress(downloaded);
}
Credits: https://stackoverflow.com/users/705297/pomatu

Android active download threads

I am using the following code for downloading file from server:
URL url = new URL(urlString);
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.setDoOutput(false);
urlConnection.connect();
StorageTools.maintainMemoryEmptyThreshold(25);
if (tempFolderFile.createNewFile()) {
tempFolderFile.createNewFile();
}
FileOutputStream fileOutput = new FileOutputStream(tempFolderFile);
InputStream inputStream = urlConnection.getInputStream();
int totalSize = urlConnection.getContentLength();
int downloadedSize = 0;
byte[] buffer = new byte[8096];
int bufferLength = 0;
while ((bufferLength = inputStream.read(buffer)) > 0) {
fileOutput.write(buffer, 0, bufferLength);
downloadedSize += bufferLength;
LOGGER.debug("Progress: downloadedSize: " + downloadedSize + "totalSize: " + totalSize);
}
fileOutput.close();
if (downloadedSize == totalSize) {
LOGGER.info("Downloaded at " + tempFolderFile.getAbsolutePath());
StorageTools.moveFile(tempFolder, targetFolder, fileName);
return true;
}
I trigger the download using a new thread into a tempfolder, move it into required folder upon download completion. How to maintain a cap on the number of active download threads and add remaining downloads to a queue ?
Also, following are my concerns in this regard:
Is there any way in which I can incorporate a threadpool executor for queuing downloads using above function ?
Does the buffersize impact the download speed ?

Please check https://developer.android.com/reference/android/app/DownloadManager.html
buffersize will not impact much. I think it should be in safe limit.

Pause/Resume http connection download

I want to be able to open a http connection to a given file in Android and start downloading it.
I also have to be able to pause the download at some point and resume it later.
How is this achieved in Android? I don't want to start the download all over again.

Such a downloader has been posted here:
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
if(ISSUE_DOWNLOAD_STATUS.intValue()==ECMConstant.ECM_DOWNLOADING){
File file=new File(DESTINATION_PATH);
if(file.exists()){
downloaded = (int) file.length();
connection.setRequestProperty("Range", "bytes="+(file.length())+"-");
}
}else{
connection.setRequestProperty("Range", "bytes=" + downloaded + "-");
}
connection.setDoInput(true);
connection.setDoOutput(true);
progressBar.setMax(connection.getContentLength());
in = new BufferedInputStream(connection.getInputStream());
fos=(downloaded==0)? new FileOutputStream(DESTINATION_PATH): new FileOutputStream(DESTINATION_PATH,true);
bout = new BufferedOutputStream(fos, 1024);
byte[] data = new byte[1024];
int x = 0;
while ((x = in.read(data, 0, 1024)) >= 0) {
bout.write(data, 0, x);
downloaded += x;
progressBar.setProgress(downloaded);
}

Zip file download in android

I have an app to download zip file content from drop box (which is publicly shared path). i wrote download code using HttpURLConnection but its not working as intended and instead is downloading a small portion (after download zip file showing 31 kb but its original size is 3mb). i am attching my code. please help me to solve this.
URL url = new URL("drop box public share url");
//create the new connection
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setAllowUserInteraction(false);
urlConnection.setInstanceFollowRedirects(true);
urlConnection.setConnectTimeout(5 * 1000);
urlConnection.setRequestMethod("GET");
urlConnection.setDoOutput(true);
urlConnection.setDoInput(true);
urlConnection.connect();
File SDCardRoot = Environment.getExternalStorageDirectory();
File file = new File(SDCardRoot,"/download/sample.zip");
FileOutputStream fileOutput = new FileOutputStream(file);
InputStream inputStream = urlConnection.getInputStream();
int totalSize = urlConnection.getContentLength();
int downloadedSize = 0;
//create a buffer...
byte[] buffer = new byte[1024];
int bufferLength = 0;
while ( (bufferLength = inputStream.read(buffer)) > 0 ) {
fileOutput.write(buffer, 0, bufferLength);
downloadedSize += bufferLength;
onProgressUpdate(downloadedSize, totalSize);
}
//close the output stream when done
fileOutput.close();
inputStream.close();

It seems that the method call:
setDoOuput(true);
makes the request a POST (see
What exactly does URLConnection.setDoOutput() affect?)
Removing it seems to fix the issue.

Try to use plain URLConnection not HttpURLConnection. And see the output.

Downloading file is slow in some devices

i am using below code to downloading file from URL.
URL url = new URL(mCoreContent.VideoURI);
HttpURLConnection c = (HttpURLConnection) url.openConnection();
c.setRequestMethod("GET");
c.setDoOutput(true);
c.connect();
lenghtOfFile = c.getContentLength();
InputStream input = c.getInputStream();
BufferedInputStream bis = new BufferedInputStream(input);
ByteArrayOutputStream output = new ByteArrayOutputStream((int) lenghtOfFile);
int buffer = 4096;
byte data[] = new byte[buffer];
int current = 0;
while ((current = bis.read(data, 0, buffer)) != -1) {
output.write(data, 0, current);
}
i tested above code with two different device. one device taking less than a minute downloading the file and another takes more than 5-10 to downloading same with same network connecting. i tested multiple times and i am getting the same result. Please help.
Thanks in advance.