I'm workin with Volley API in my WebServices, and then I'll write the data in with SQLITE.
Webservices that comes with a JSON with many itens, each of then has data and a image, and I need to keep this image in my cache to display offline in a ListView and later on a detail screen. In the future the user will clean these itens and clear the imagens of them too.
Well, how can I save these images in my local DB and link with each Item that I have from the JSON?
I will be, in 90% of the time, offline. I will only stay online for synchronizing and download the updated server items.
For dealing with images in Android the benchmark is to use Picasso library. It takes care of:
Handling ImageView recycling and download cancelation in an adapter;
Complex image transformations with minimal memory use;
Automatic memory and disk caching.
Besides that, if you're going to display images in lists and need animation to enhance your UI, I strongly recommend changing from ListView to RecyclerView. It is not recommended to store the images in the DB, you would lose time converting this from/to blobs (check here and here). Said that, what I suggest is:
Use Picasso to load the images from the URL provided in the JSON;
Implement a Custom target to handle the image file downloaded by Picasso;
Save the image in a folder inside your app directory;
Use RecyclerView to display the images; (optional)
If you need a project example where those things are done, you can check this. In this project I follow the approache I've described above. You can download the app from the store and see how it will download the images.
Quicky-guide:
To use Picasso add this to you module's gradle file: compile 'com.squareup.picasso:picasso:2.5.2'
Create a class that implements import com.squareup.picasso.Callback;:
public class ImageWarehouse implements Callback {
private static final String TAG = "ImageWarehouse";
private String mDirectory;
private String mFileName;
private ImageView mContainer;
#Inject
App mApplication;
public ImageWarehouse(String fileName, ImageView container, String directory) {
this.mFileName = fileName;
this.mContainer = container;
this.mDirectory = directory;
this.getStorageDir();
}
#Override
public void onSuccess() {
if (this.isExternalStorageWritable()) {
final Bitmap bitmap = ((BitmapDrawable) this.mContainer.getDrawable()).getBitmap();
new AsyncTask<Void, Void, File>() {
#Override
protected File doInBackground(Void... params) {
File file = null;
try {
file = new File(ImageWarehouse.this.getStorageDir().getPath().concat("/").concat(ImageWarehouse.this.mFileName.concat(Constants.MEDIA_EXTENSION)));
file.createNewFile();
FileOutputStream ostream = new FileOutputStream(file);
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, ostream);
ostream.close();
} catch (Exception e) {
Log.e(TAG, "External Storage is not available");
}
return file;
}
}.execute();
} else {
Log.e(TAG, "External Storage is not available");
}
}
#Override
public void onError() {
}
public boolean isExternalStorageWritable() {
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state)) {
return true;
}
return false;
}
public File getStorageDir() {
File file = new File(Environment.getExternalStorageDirectory(), Constants.MEDIA_DIRECTORY.concat(this.mDirectory));
if (!file.mkdirs()) {
}
return file;
}
}
Call Picasso in order to display the image in the layout and save it to the specified path:
Picasso
.load(URL)
.fit()
.centerCrop()
.into(viewHolder.cover,
new ImageWarehouse(
name,
viewHolder.cover,
Constants.MEDIA_CHARACTER
)
);
You can user Android-Universal-Image-Loader it is also cache image in memory. it is show from cache when next time same url used in imageloader for get image
see below link for complete source code of Universal Image Loader Example.
Android - Universal Image Loader
You can save your images in Sqlite as blob and can retrieve it when required. Create table as
create table sometable(id integer primary key autoincrement,photo BLOB);
And save the image as
//convert image into byte[]
ByteArrayOutputStream baos = new ByteArrayOutputStream();
Bitmap bitmap = ((BitmapDrawable)getResources().getDrawable(R.drawable.common)).getBitmap();
bitmap.compress(Bitmap.CompressFormat.PNG, 100, baos);
byte[] photo = baos.toByteArray();
//And now store this image
ContentValues initialValues = new ContentValues();
initialValues.put("photo",photo);
return db.insert("sometable", null, initialValues);
And retrieve image as
Cursor cur=your query;
while(cur.moveToNext())
{
byte[] photo=cur.getBlob(index of blob cloumn);
}
Related
Is it possible to show previously downloaded image in Glide as placeholder while downloading new image.
Like I have an image loaded in imageview using glide. Now the imageurl is changed, so while loading this new image is it possible to keep displaying the old image (might be from cache).
What I want is while the new image is being loaded from the URL, is it possible to keep the current image as placeholder.
I found the answer to this in the discussion here - https://github.com/bumptech/glide/issues/527#issuecomment-148840717.
Intuitively I also thought of using placeholder(), but the problem is that as soon as you load the second image, you loose the reference to the first one. You can still reference it but it is not safe as it may be reused by Glide or recycled.
The proposed solution from the discussion is to use thumbnail() and load the first image again. The load will return the first image immediately from the memory cache and it will look as if the image did not change until the second image is loaded:
String currentImageUrl = ...;
String newImageUrl = ...;
Glide.with(this)
.load(newImageUrl)
.thumbnail(Glide.with(this)
.load(currentImageUrl)
.fitCenter()
)
.fitCenter()
.into(imageView);
Glide have a capability of getting the bitmap of the image from that url, so just get it and then save it to a desired storage into your phone, and after that in your .placeholder() just use that bitmap when you are trying to get another image , take a look at this snippet
/** Download the image using Glide **/
Bitmap theBitmap = null;
theBitmap = Glide.
with(YourActivity.this).
asBitmap().
load("Url of your image").
into(-1, -1).
get(); //with this we get the bitmap of that url
saveToInternalStorage(theBitmap, getApplicationContext(), "your preferred image name");
/** Save it on your device **/
public String saveToInternalStorage(Bitmap bitmapImage, Context context, String name){
ContextWrapper cw = new ContextWrapper(context);
// path to /data/data/yourapp/app_data/imageDir
String name_="foldername"; //Folder name in device android/data/
File directory = cw.getDir(name, Context.MODE_PRIVATE);
// Create imageDir
File mypath=new File(directory,name_);
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);
fos.close();
} catch (Exception e) {
e.printStackTrace();
}
Log.e("absolutepath ", directory.getAbsolutePath());
return directory.getAbsolutePath();
}
/** Method to retrieve image from your device **/
public Bitmap loadImageFromStorage(String path, String name)
{
Bitmap b;
String name_= name; //your folderName
try {
File f=new File(path, name_);
b = BitmapFactory.decodeStream(new FileInputStream(f));
return b;
}
catch (FileNotFoundException e)
{
e.printStackTrace();
}
return null;
}
/** Retrieve your image from device and set to imageview **/
//Provide your image path and name of the image your previously used.
Bitmap b= loadImageFromStorage(String path, String name)
ImageView img=(ImageView)findViewById(R.id.your_image_id);
img.setImageBitmap(b);
I'm working on a school android project.
I need to have a download button which downloads a picture(when we have class)
And after display it in another activity(even in offline mode, and after quiting)
I've tried picasso, but I can't get it to save and use it in offline mode.
For you to support offline mode, You need to Save the image on your disk because when your cache is cleared, The image is cleared as well.
You can easily use Glide to Solve this, also storing on device and retrieving
You can Learn more about Glide here http://inthecheesefactory.com/blog/get-to-know-glide-recommended-by-google/en
/** Download the image using Glide **/
Bitmap theBitmap = null;
theBitmap = Glide.
with(YourActivity.this).
load("Url of your image").
asBitmap().
into(-1, -1).
get();
saveToInternalStorage(theBitmap, getApplicationContext(), "your preferred image name");
/** Save it on your device **/
public String saveToInternalStorage(Bitmap bitmapImage, Context context, String name){
ContextWrapper cw = new ContextWrapper(context);
// path to /data/data/yourapp/app_data/imageDir
String name_="foldername"; //Folder name in device android/data/
File directory = cw.getDir(name_, Context.MODE_PRIVATE);
// Create imageDir
File mypath=new File(directory,name);
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);
fos.close();
} catch (Exception e) {
e.printStackTrace();
}
Log.e("absolutepath ", directory.getAbsolutePath());
return directory.getAbsolutePath();
}
/** Method to retrieve image from your device **/
public Bitmap loadImageFromStorage(String path, String name)
{
Bitmap b;
String name_="foldername";
try {
File f=new File(path, name_);
b = BitmapFactory.decodeStream(new FileInputStream(f));
return b;
}
catch (FileNotFoundException e)
{
e.printStackTrace();
}
return null;
}
/** Retrieve your image from device and set to imageview **/
//Provide your image path and name of the image your previously used.
Bitmap b= loadImageFromStorage(String path, String name)
ImageView img=(ImageView)findViewById(R.id.your_image_id);
img.setImageBitmap(b);
Thanks to #Droidman :
How to download and save an image in Android
Of course you can perform downloading and managing images by yourself,
but if your project is quite complex already, there are a lot of
libraries around and you do not need to reinvent the wheel. I won't
post code this time since there are a lot of examples, but I'm going
to tell you about 2 most useful libraries (IMO) related to image
downloading.
1) Android Volley. A powerful networking library created by Google and
covered by official documentation. POST'ing or GET'ing data, images,
JSON - volley will manage it for you. Using volley just for image
downloading is a bit of an overkill in my opinion.
2) Picasso
Image downloading and caching, perfect for
ListView/GridView/RecyclerView. Apache 2.0 license.
3) Fresco
Quite a new image loading library created by Facebook. Progressive
JPEG streaming, gifs and more. Apache 2.0
You could use Android Library called Universal Image Loader:
https://github.com/nostra13/Android-Universal-Image-Loader
Universal Image Loader provide many ways to load the image.
"file:///mnt/sdcard/image.png" // from SD card
"file:///mnt/sdcard/video.mp4" // from SD card (video thumbnail)
"content://media/external/images/media/13" // from content provider
"content://media/external/video/media/13" // from content provider (video thumbnail)
"assets://image.png" // from assets
"drawable://" + R.drawable.img // from drawables (non-9patch images)
But all these way load image form file, I need a way to load from memory since my images was encrypted and stored in the assets folder, When I display this image, I need the following steps.
decrypt the image into bytes array.
Create bitmap from the bytes.
Load/display the image.
So it's something like this. Is that possible?
Bitmap bitmap = decrypt(encryptedImageFile);
imageLoader.displayImage(bitmap, imageView);
Currently, I am considering to save the bitmap to file and load the file, but this will take more time.
I believe the below is what you are seeking if your images are stored in image folder in assets directory, then you can get the list of images
private List<String> getImage(Context conetx) throws IOException {
AssetManager assetManager =conetx.getAssets();
String[] files = assetManager.list("image");
List<String> it=Arrays.asList(files);
return it;
}
As a note, instead of using assets dir, put the file into /res/raw and you can then access it using the following URI
android.resource://com.your.packagename/" + R.raw.<nameoffile>
I think you need to understand this. You must know, If you have read the source code of universal-image-loader, the order of loading a image into a ImageView after the image's url is provided, is: memory, SDCard(if set), internet. That means after you called, ImageLoader.display(url, imageview);, it will look for the Bitmap from memory first, if it doesn't exist, if will look for the file of the image from SDCard then, if the file exist, if will convert the file into a Bitmap, then load the Bitmap into the ImageView and store it in memory. But if the file doesn't exist, it will download the image file of the url, then store the file into the SDCard and convert the file into a Bitmap and load the Bitmap into memory. Most importantly, I recommend you to read source codes of it, if you are confused with what I post above.
So, it is unnecessary for you to load the Bitmap from memory, ImageLoader will do it for you.
Lets choose own scheme so our URIs will look like "stream://...".
Then implement ImageDownloader. We should catch URIs with our scheme and return image stream.
public class StreamImageDownloader extends BaseImageDownloader {
private static final String SCHEME_STREAM = "stream";
private static final String STREAM_URI_PREFIX = SCHEME_STREAM + "://";
public StreamImageDownloader(Context context) {
super(context);
}
#Override
protected InputStream getStreamFromOtherSource(String imageUri, Object extra) throws IOException {
if (imageUri.startsWith(STREAM_URI_PREFIX)) {
return (InputStream) extra;
} else {
return super.getStreamFromOtherSource(imageUri, extra);
}
}
}
DisplayImageOptions defaultOptions = new DisplayImageOptions.Builder()
.build();
ImageLoaderConfiguration config = new ImageLoaderConfiguration.Builder(getApplicationContext())
.defaultDisplayImageOptions(defaultOptions)
.imageDownloader(new StreamImageDownloader(getApplicationContext()))
.build();
ImageLoader.getInstance().init(config);
ByteArrayInputStream stream = new ByteArrayInputStream(imgBytes);
String imageId = "stream://" + stream.hashCode();
DisplayImageOptions options = new DisplayImageOptions.Builder()
.extraForDownloader(stream)
.build();
ImageLoader.getInstance().displayImage(imageId, imageView, options);
In my application the system will download images from an url and save it into phone memory. (I did not included url address in the question) On top of that, it will also save data into sqlite database. Data that save is file name, filepath and file size. But currently once I go through the download process whether the download complete or fail in the middle of the process, it also will insert into the database.
Is there any way that I can check whether the download process is completed or not?
GalleryScreen.this.runOnUiThread(new Runnable() {
#Override
public void run() {
boolean isDownloadResult = false;
int NumIncrease = 0;
Log.i(TAG, "NumberIncrease:" +NumIncrease);
Toast.makeText(getApplicationContext(), "Downloading.............>>>>>>>>>>>", Toast.LENGTH_SHORT).show();
Bitmap bm;
InputStream in;
try{
in = new java.net.URL(URL).openStream();
bm = BitmapFactory.decodeStream(new PatchInputStream(in));
File storage = new File(Environment.getExternalStorageDirectory() + File.separator + "/Images/");
Log.i(TAG,"storage:" +storage);
Log.i(TAG,"storage:" +storage.getAbsolutePath());
if(!storage.exists()){
storage.mkdirs();
}
String FileName = "/"+CONTENT_ID+".jpg";
FileOutputStream fos = new FileOutputStream(storage + FileName);
bm.compress(Bitmap.CompressFormat.JPEG, 85, fos);
String filepath = storage + FileName;
File filecheck = new File (filepath);
long fileSize = filecheck.length();
fos.flush();
fos.close();
Log.i(TAG, "bm:" +bm);
Log.i(TAG, "fos:" +fos);
Log.i(TAG, "filesize:" +fileSize);
Log.i(TAG, "filepath:" +filepath);
helper.insert_content(filepath, fileSize, requestTime);
isDownload = false;
}
catch(IOException e1){
e1.printStackTrace();
}
}
});
Please use AsyncTask. AsyncTask enables proper and easy use of the UI thread. This class allows to perform background operations and publish results on the UI thread without having to manipulate threads and/or handlers.
AsyncTask is designed to be a helper class around Thread and Handler and does not constitute a generic threading framework. AsyncTasks should ideally be used for short operations (a few seconds at the most.)
you can just use an anonymous class for the async task. This would like this:
ImageView mChart = (ImageView) findViewById(R.id.imageview);
String URL = "http://www...anything ...";
mChart.setTag(URL);
new DownloadImageTask.execute(mChart);
The Task class:
public class DownloadImagesTask extends AsyncTask<ImageView, Void, Bitmap> {
ImageView imageView = null;
#Override
protected Bitmap doInBackground(ImageView... imageViews) {
this.imageView = imageViews[0];
return download_Image((String)imageView.getTag());
}
#Override
protected void onPostExecute(Bitmap result) {
imageView.setImageBitmap(result);
}
private Bitmap download_Image(String url) {
...
}
Here, onPostExecute, you can easily check whether the process of download image is completed or not.
Further reading
http://developer.android.com/reference/android/os/AsyncTask.html
Loading Image using AsyncTask
Android : Loading an image from the Web with Asynctask
Android Help with adding a progress dialog while image loading?
EDIT:
If you are trying to download larger files, you might consider
putting your application into some type of Service as this would
potentially take a few hours.
You can consider using Download Manger for newer devices
(with Android 2.3+)
Also a nice resource ->
Download a file with Android, and showing the progress in a ProgressDialog
I am downloading images from server into the ListView , now to perform this task i am using ImageDownloader example code. so far its working fine.
But i want to save images of ListView in a SD card but i am confused when to store the images as images are being downloaded Asynchronously and because of ViewHolder pattern its little tough for me to judge.
Once i stored it in a SD card next time i want to read it from memory only.
ImageDownload is storing bitmap in cache and fetching it from there once it gets downloaded.But the problem is its behavior is not predictable.
Sometimes it downloads from server and sometimes from cache.
so can anyone help me in finding what is the proper place to store the images in sd card once.
Modify your ImageDownloader class to save the image like this :
add a parameter to download method like :
download(String url, ImageView imageView, Boolean saveData)
make a global variable saveData in yout ID class :
private Boolean saveData;
and store in it the value given as parameter in download dmethod:
this.saveData = saveData;
and the BitmapDownloaderTask's onPostExecute method should look like this :
#Override
protected void onPostExecute(Bitmap bitmap) {
if (isCancelled()) {
bitmap = null;
}
addBitmapToCache(url, bitmap);
if (saveData == true) {
try {
FileOutputStream out = new FileOutputStream(path);
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, out);
} catch (Exception e) {
e.printStackTrace();
}
}
if (imageViewReference != null) {
ImageView imageView = imageViewReference.get();
BitmapDownloaderTask bitmapDownloaderTask = getBitmapDownloaderTask(imageView);
// Change bitmap only if this process is still associated with it
if (this == bitmapDownloaderTask) {
imageView.setImageBitmap(bitmap);
}
}
}
where path is the path were you want to save the image .
and next time before you want to load the image you have to see if it is already downloaded and load it from the path otherwise call ImageDownloader.
that's it! enjoy!