Develop Reference

saving downloaded file to internal storage java/android fails

I have an app who has to download some generated images (PNG).
I tried the standard approach ImageDownloader extends AsyncTask, doInBackground() retrieves the image and the onPostExecute() will try to save it to internal image.
(Part of the) code is below:
public class HandleImages extends AppCompatActivity {
String filename = "";
public boolean saveImageToInternalStorage(Bitmap image) {
try {
FileOutputStream fos = openFileOutput(filename, Context.MODE_PRIVATE);
image.compress(Bitmap.CompressFormat.PNG, 100, fos);
fos.close();
return true;
} catch (Exception e) {
e.printStackTrace();
return false;
}
}
public Bitmap retrieveImage(String url){
ImageDownloader task = new ImageDownloader();
Bitmap image = Bitmap.createBitmap(1, 1, Bitmap.Config.ARGB_8888);
try {
image = task.execute(url).get();
} catch (InterruptedException e) {
MainActivity.debb("InterruptedException - " + e.getMessage() + " in " + new Object(){}.getClass().getEnclosingMethod().getName());
e.printStackTrace();
} catch (ExecutionException e) {
MainActivity.debb("ExecutionException - " + e.getMessage() + " in " + new Object(){}.getClass().getEnclosingMethod().getName());
e.printStackTrace();
}
return image;
}
public class ImageDownloader extends AsyncTask<String, Void, Bitmap> {
#Override
protected Bitmap doInBackground(String... urls) {
try {
String[] filenames = urls[0].split("/");
filename = filenames[filenames.length-1] + ".jpg";
URL url = new URL(urls[0]);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.connect();
InputStream inputStream = connection.getInputStream();
return BitmapFactory.decodeStream(inputStream);
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
#Override
protected void onPostExecute(Bitmap bitmap) {
super.onPostExecute(bitmap);
if (bitmap != null)
saveImageToInternalStorage(bitmap);
}
}
}
and the error that I get is: java.lang.NullPointerException: Attempt to invoke virtual method 'java.io.FileOutputStream android.content.Context.openFileOutput(java.lang.String, int)' on a null object reference.
It seems that the FileOutputStream fos = openFileOutput(..) fails, but have no idea why.
Also tried to prepend a path (sdCard.getPath() + "/" +) to the filename. As expected it did not make any difference.
Images are ok, I can see them in the browser. Also tried with uploaded images - instead of the generated ones, same result.
This is pretty odd, does anyone have any idea?
Thanks!

private String saveToInternalStorage(Bitmap bitmapImage){
ContextWrapper cw = new ContextWrapper(getApplicationContext());
// path to /data/data/yourapp/app_data/imageDir
File directory = cw.getDir("imageDir", Context.MODE_PRIVATE);
// Create imageDir
File mypath=new File(directory,"profile.jpg");
FileOutputStream fos = null;
try {
fos = new FileOutputStream(mypath);
// Use the compress method on the BitMap object to write image to the OutputStream
bitmapImage.compress(Bitmap.CompressFormat.PNG, 100, fos);
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
return directory.getAbsolutePath();
}
Hope this function helps you. If this doesn't help feel free to ask

Downloading images from AWS gives me corrupt files

I'm trying to download images that are hosted on Amazon Web Services. My methods work fine on any other host, but downloading an image off this url for example http://s3-eu-west-1.amazonaws.com/static.melkweg.nl/uploads/images/scaled/event_header/18226 is giving me trouble. It does download, but the file is only 49kb big and cannot be opened.
I've tried different methods such as Apache's FileUtils copyURLToFile, BufferedInputStream, ImageIO, etc. Some throw errors, most just download a corrupt file.
Here are the methods I've tried:
public static void downloadApache(String imageurl, String target)
{
try
{
File file = new File(target);
URL url = new URL(imageurl);
FileUtils.copyURLToFile(url, file);
}
catch(Exception e)
{
System.err.println("[3]Something went wrong.");
}
}
public static void downloadImage(String imageurl, String name)
{
try
{
URL url = new URL(imageurl);
InputStream in = new BufferedInputStream(url.openStream());
OutputStream out = new BufferedOutputStream(new FileOutputStream(name));
for ( int i; (i = in.read()) != -1; ) {
out.write(i);
}
in.close();
out.close();
}
catch(Exception e)
{
e.printStackTrace();
System.err.println("[0]Something went wrong.");
}
}
public static void downloadImageIO(String imageurl, String target)
{
try
{
URL url = new URL(imageurl);
BufferedImage image = ImageIO.read(url);
ImageIO.write(image, "jpg", new File(target));
}
catch(Exception e)
{
e.printStackTrace();
System.err.println("[1]Something went wrong.");
}
}
public static void downloadImageCopy(String imageurl, String target)
{
try
{
try (InputStream in = new URL(imageurl).openStream()) {
Files.copy(in, Paths.get(target), StandardCopyOption.REPLACE_EXISTING);
}
}
catch(Exception e)
{
e.printStackTrace();
System.err.println("[2]Something went wrong.");
}
}
And here's the main method if that is of any interest
public static void main(String[] args)
{
String imageurl = "http://s3-eu-west-1.amazonaws.com/static.melkweg.nl/uploads/images/scaled/event_header/18226";
String name = "downloaded_image.jpg";
String target = "C:/Users/Robotic/Downloads/" + name;
Download.downloadImage(imageurl, name);
Download.downloadImageCopy(imageurl, target);
Download.downloadImageIO(imageurl, target);
Download.downloadApache(imageurl, target);
}
Thanks in advance.

The file that you are getting from S3 is gzip compressed, you need to decompress it before trying to read it.
$ wget http://s3-eu-west-1.amazonaws.com/static.melkweg.nl/uploads/images/scaled/event_header/18226
$ file 18226
18226: gzip compressed data, from Unix

As pointed out in the earlier answer, it is in gzip format.
You can use the following method and get the file unzipped
public static void downloadApache(String imageurl, String target) {
try {
File file = new File(target+".gzip");
URL url = new URL(imageurl);
FileUtils.copyURLToFile(url, file);
byte[] buffer = new byte[1024];
try {
java.util.zip.GZIPInputStream gzis = new java.util.zip.GZIPInputStream(new FileInputStream(file));
FileOutputStream out = new FileOutputStream(target);
int len;
while ((len = gzis.read(buffer)) > 0) {
out.write(buffer, 0, len);
}
gzis.close();
out.close();
} catch (IOException ex) {
ex.printStackTrace();
}
} catch (Exception e) {
System.err.println("[3]Something went wrong.");
}
}

android downloading multiple files with InputStream FileOutputStream

So I have an app which downloads certain files, dedicated to a client of mine who is hosting his files on a remote location, and i'm doing so using the code below:
public class DownloadService extends IntentService {
private int result = Activity.RESULT_CANCELED;
public DownloadService() {
super("DownloadService");
}
#Override
protected void onHandleIntent(Intent intent) {
String urlPath = intent.getStringExtra(URL);
String fileName = intent.getStringExtra(FILENAME);
File output = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS),
fileName);
if (output.exists()) {
output.delete();
}
URLConnection streamConnection = null;
InputStream stream = null;
FileOutputStream fos = null;
try {
URL url = new URL(urlPath);
streamConnection = url.openConnection();
stream = streamConnection.getInputStream();
streamConnection.connect();
long lengthofFile = streamConnection.getContentLength();
InputStream reader = stream;
bis = new BufferedInputStream(reader);
fos = new FileOutputStream(output.getPath());
int next = -1;
int progress = 0;
int bytesRead = 0;
byte buffer[] = new byte[1024];
while ((bytesRead = bis.read(buffer)) > 0) {
fos.write(buffer, 0, bytesRead);
progress += bytesRead;
int progressUpdate = (int)((progress * 100) / lengthofFile);
Intent testIntent = new Intent(".MESSAGE_INTENT");
testIntent.putExtra(PERCENTAGE, progressUpdate);
sendBroadcast(testIntent);
}
result = Activity.RESULT_OK;
fos.flush();
} catch (Exception e) {
e.printStackTrace();
} finally {
if (stream != null) {
try {
stream.close();
bis.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (fos != null) {
try {
fos.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
publishResults(output.getAbsolutePath(), result);
}
private void publishResults(String outputPath, int result) {
Intent intent = new Intent(".MESSAGE_INTENT");
intent.putExtra(FILEPATH, outputPath);
intent.putExtra(RESULT, result);
sendBroadcast(intent);
}
}
and to call this service i would use:
Intent intent = new Intent(MainActivity.getAppContext(), DownloadService.class);
intent.putExtra(DownloadService.FILENAME, downloadFileName[item]);
intent.putExtra(DownloadService.URL, urlDownload[item]);
MainActivity.getAppContext().startService(intent);
now this allows user to download one file at a time, however if the user downloads another file, the second file will have to wait till the first file is done downloading.
now what is happening in my case is:
1- First download FILE_1 is downloading, and in the status is says FILE_1.
2- User clicks a new file download, the status changes the first file name to the second file name, and waits till FILE_1 finishes download to start with FILE_2 however the active download is changed from FILE_1 to FILE_2.
questions:
is there a way to call DownloadService multiple times for multiple files?
is it possible to fix the problem i'm facing? treating download intent services as two different intents?
UPDATE
I managed to solve this issue by assigning a unique Int ID per file, each ID will point to a position in the listview which displays the files being downloaded or queued, then i work with each file on it's own.

Following code uses commons-io-2.4.jar library to make your work easy by handling low level data movements as you would focus on method in hand
URL someUrl = new URL("your url String"); //
File someFile = new File("your file, where you want to save the data");
FileUtils.copyURLToFile(someUrl, someFile );
if you want to call this statement few time to download different files from the server following code might give you an idea what you might want to do, but you will have to write it's equivalent code to run in android which you want to probably AsyncTask
import java.io.File;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import org.apache.commons.io.FileUtils;
public class DownloadTest {
public static void main(String[] args) {
Thread thread = new Thread(){
#Override
public void run() {
// TODO Auto-generated method stub
super.run();
try {
dowanloadFile(new URL("some url"), new File("some file"));
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
};
thread.start();
}
private static void dowanloadFile(URL url, File file){
try {
FileUtils.copyURLToFile(url, file );
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}

Filenotfoundexception on newer versions of android API Level 4 and later

I am working on a project with google maps where i try to retrieve bitmaps from URL and save it to internal memory.After downloading the bitmap into internal memory i try to read it from memory using the following code:
public Bitmap getImageBitmap(Context context, String name) {
FileInputStream fis = null;
try {
File myFile = new File (path_file + File.separator + name);
fis = new FileInputStream(myFile);
Bitmap b = BitmapFactory.decodeStream(fis);
return b;
} catch(Exception e) {
return null;
} finally {
if(fis!=null) {
try {
fis.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
The problem is that the code works fine on Android 2.6 , but it throws Filenotfoundexception at this line
fis = new FileInputStream(myFile);
Why does the code work fine on older versions of android but throws exception on newer versions of android?How do i fix the issue?
EDIT:
The issue was with the code which downloads the bitmap:
The code that i am using is:
public void downloadfile(String path,String filepath)
{
try
{
URL url = new URL(path);
URLConnection ucon = url.openConnection();
ucon.setReadTimeout(5000);
ucon.setConnectTimeout(10000);
InputStream is = ucon.getInputStream();
BufferedInputStream inStream = new BufferedInputStream(is, 1024 * 5);
File file = new File(filepath);
file.createNewFile();
FileOutputStream outStream = new FileOutputStream(file);
byte[] buff = new byte[5 * 1024];
int len;
while ((len = inStream.read(buff)) != -1)
{
outStream.write(buff, 0, len);
}
outStream.flush();
outStream.close();
inStream.close();
}
catch(Exception e)
{
e.printStackTrace();
}
}
The code throws NetworkonMainThreadException at this line: InputStream is = ucon.getInputStream();
This error is thrown only on the newer android version.Please help!!

Try this..
Just use
path_file=MainActivity.this.getFilesDir();
EDIT
class downloadfile extends AsyncTask<String, Void, Void> {
protected Void doInBackground(String... urls) {
try
{
URL url = new URL(path);
URLConnection ucon = url.openConnection();
ucon.setReadTimeout(5000);
ucon.setConnectTimeout(10000);
InputStream is = ucon.getInputStream();
BufferedInputStream inStream = new BufferedInputStream(is, 1024 * 5);
File file = new File(filepath);
file.createNewFile();
FileOutputStream outStream = new FileOutputStream(file);
byte[] buff = new byte[5 * 1024];
int len;
while ((len = inStream.read(buff)) != -1)
{
outStream.write(buff, 0, len);
}
outStream.flush();
outStream.close();
inStream.close();
}
catch(Exception e)
{
e.printStackTrace();
}
}
protected void onPostExecute() {
// TODO: check this.exception
// TODO: do something with the feed
}
}
Instead if calling downloadfile method use below
new downloadfile().execute();

You are trying to perform a network related operation in Main thread,you are getting this NetworkonMainThreadException.
Refer to my answer here for more explanation.
In your case try downloading the bitmap file in worker thread. You can use an Asynctask for it and download bitmap in doInBackground().
Refer this example

How to start and stop the download of multiple files in android

i've an activity with a button and a label.
On button click my app must download several files ( about 9000 ).
If user clicks again on button, the download must stop and on another click it must start from the beginning.
So this is what i do:
In activity:
file.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
Button b = (Button)v;
if(canFile){
b.setText("Stop download");
changeLabelInfo("Getting file list...");
labelFile.setVisibility(View.VISIBLE);
fileTask.start();
}else{
b.setText("Download files");
if(fileTask.isAlive()){
fileTask.interrupt();
fileTask = null;
fileTask = new UpdateFilesThread(this);
}
labelFile.setVisibility(View.INVISIBLE);
Kernel.setManualUpdate("file",false);
}
canFile = !canFile;
}
});
The thread that must download files is UpdateFilesThread:
public class UpdateFilesThread extends Thread{
private MainActivity activity;
private final String rootPath = "/mnt/local/";
public UpdateFilesThread(MainActivity activity){
this.activity = activity;
}
public void run(){
String json = getFilesURL();
JSONObject a = (JSONObject)JSONValue.parse(json);
boolean isZip = false,canDownload = true;
String[] keys = new String[]{"key1","key2","key3","key4"};
for(String key:keys){
Object folder = (Object)a.get(key);
if(folder instanceof JSONObject){
JSONObject fold = (JSONObject)folder;
for(Object path_o:fold.keySet()){
path = path_o.toString().replace(" ", "%20");
if(local.endsWith(".php")){
isZip = true;
try {
Jsoup.connect(mywebserviceURL).data("path",path).timeout(0).post(); // If php generate zip containing php file
} catch (IOException e) {
canDownload = false;
}
}
if(canDownload){
try{
if(downloadFromUrl(path,isZip))
//SAVE URL DOWNLOADED
}catch(Exception e){
e.printStackTrace();
}
}
canDownload = true;
isZip = false;
}
}
}
a.remove(key);
}
private String getFilesURL(){
try {
MultipartEntity entity = new MultipartEntity(HttpMultipartMode.BROWSER_COMPATIBLE);
entity.addPart("type", new StringBody("all"));
HttpPost post = new HttpPost("mywebserviceURL");
post.setEntity(entity);
HttpClient client = new DefaultHttpClient();
HttpResponse response = client.execute(post);
return EntityUtils.toString(response.getEntity());
} catch (UnsupportedEncodingException e) {
Support.writeError(e, null);
e.printStackTrace();
return "";
} catch (ClientProtocolException e) {
Support.writeError(e, null);
e.printStackTrace();
return "";
} catch (ParseException e) {
Support.writeError(e, null);
e.printStackTrace();
return "";
} catch (IOException e) {
Support.writeError(e, null);
e.printStackTrace();
return "";
}
}
public boolean downloadFromUrl(String path,boolean isZip){
InputStream is = null;
FileOutputStream fos = null;
String localFilename = rootPath+path;
String local = isZip?rootPath+"tmp.zip":localFilename;
boolean return_ = false;
try {
URL url = new URL(isZip?mywebserviceURLZip:mywebserviceURLZip+path);
URLConnection urlConn = url.openConnection();
urlConn.setReadTimeout(0);
is = urlConn.getInputStream();
fos = new FileOutputStream(local);
byte[] buffer = new byte[51200];
int len;
while ((len = is.read(buffer)) > 0) {
fos.write(buffer, 0, len);
}
fos.close();
is.close();
if(isZip){
ZipFile zip = new ZipFile(local);
zip.extractAll(rootPath);
new File(local).delete();
}
return_= true;
}catch(Exception e){
e.printStackTrace();
return false;
}
return return_;
}
}
My problem borns when user clicks two time the button ( stop downloading and start again ).
The prompt error says that the thread is already startend and in running.. how can i solve it? I know that asyncTask should be better but i've problem cause in my application there are so many thread running and the device is so poorly peforming..
It's possible to stop definitelly a thread? are there other better solution?

Try implementing an AsyncTask. When the user first taps the button call the task's execute (Params... params). On the second tap call the task's cancel (boolean mayInterruptIfRunning). Put the download functionality in the task's doInBackground (Params... params)

Your run thread needs to occasionally check isInterrupted() and exit if it returns true. Otherwise the thread will never be canceled.
I think your entire architecture is wrong though. Downloading 9000 files onto a mobile phone? Even if each file is only 1KB, that's a huge amount of memory for a mobile app. And at the very least you ought to zip up that data and download a zip, for your own sanity.