Android - Image View & Download

You will get Final Output:

Step 1 First create new Project with the following permission.

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

Step 2 Create new Constant.java file in our Project.

public class Constant {
 
public static String IMAGE_BASE_URL = "http://www.theappguruz.com/android/demo_app/images/";
 
// here we are created folder with package name so when user uninstall the
// application remove all the storage data of that application
public static String STORE_IN_FOLDER = android.os.Environment
.getExternalStorageDirectory().toString()
+ "/Android/data/com.theappguruz/theappguruz";
}

Step 3 Images.Java File

Create another new class Images.java. And add getImageId() method in this class.

public class Images {
 
private Random randNo;
private ArrayList imageName;
 
public Images() {
imageName = new ArrayList();
imageName.add("a1");
imageName.add("a2");
imageName.add("a3");
imageName.add("a4");
imageName.add("a5");
}
 
public String getImageId() {
randNo = new Random();
return imageName.get(randNo.nextInt(imageName.size()));
}
}

Step 4 ImageViewAndDownload.Java file

Now Start Coding for the imageview and download. Now in Main Activity file named ImageViewAndDownload.java and put following code into class.

public class ImageViewAndDownload extends Activity implements OnClickListener {
 
private Button btnImageDownload;
private ProgressDialog pd;
private ImageView viewDownloadImage;
private Images imageId;
private File folderName;
private String imageName;
private Handler handler = new Handler() {
public void handleMessage(android.os.Message msg) {
if (msg.what == 1) {
if (pd != null) {
pd.dismiss();
}
Utils.showNetworkAlert(ImageViewAndDownload.this);
} else if (msg.what == 2) {
if (pd != null) {
pd.dismiss();
}
Utils.displayMessage("Image downloade succesfully",
ImageViewAndDownload.this);
// Media scaning
sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED,
Uri.parse("file://"
+ Environment.getExternalStorageDirectory())));
 
} else if (msg.what == 3) {
if (pd != null) {
pd.dismiss();
}
Utils.displayMessage("Image already downloaded ",
ImageViewAndDownload.this);
} else if (msg.what == 4) {
if (pd != null) {
pd.dismiss();
}
displayImageFromUrl((Bitmap) msg.obj);
}
 
}
};
 
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.imagedisplay);
 
viewDownloadImage = (ImageView) findViewById(R.id.viewImage);
btnImageDownload = (Button) findViewById(R.id.btnImageDownload);
imageId = new Images();
imageName = imageId.getImageId();
LoadImageFromWeb(Constant.IMAGE_BASE_URL + File.separator + imageName);
btnImageDownload.setOnClickListener(this);
}
 
// image display from the webview
private void LoadImageFromWeb(final String url1) {
pd = ProgressDialog.show(ImageViewAndDownload.this, "", "Loading Image....",    true, false);
new Thread(new Runnable() {
public void run() {
try {
URL url = new URL(url1);
HttpURLConnection connection = (HttpURLConnection) url
.openConnection();
 
InputStream is = connection.getInputStream();
 
Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeStream(is, null, options);
 
if (options.outWidth > 3000 || options.outHeight > 2000) {
options.inSampleSize = 4;
} else if (options.outWidth > 2000
|| options.outHeight > 1500) {
options.inSampleSize = 3;
} else if (options.outWidth > 1000
|| options.outHeight > 1000) {
options.inSampleSize = 2;
}
options.inJustDecodeBounds = false;
 
is.close();
is = getHTTPConnectionInputStream(url1);
Bitmap myBitmap = BitmapFactory.decodeStream(is, null,
options);
is.close();
 
if (myBitmap != null) {
Message msg = new Message();
msg.obj = myBitmap;
msg.what = 4;
handler.sendMessage(msg);
} else {
handler.sendEmptyMessage(1);
}
} catch (Exception e) {
e.printStackTrace();
}
}
}).start();
}
 
public InputStream getHTTPConnectionInputStream(String url1) {
URL url;
InputStream is = null;
try {
url = new URL(url1);
HttpURLConnection connection = (HttpURLConnection) url
.openConnection();
is = connection.getInputStream();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return is;
}
 
//set display image to Imageview
public void displayImageFromUrl(Bitmap obj) {
viewDownloadImage.setImageBitmap(obj);
}
 
//click on ImageDownload button
public void onClick(View v) {
if (v == btnImageDownload) {
pd = ProgressDialog.show(ImageViewAndDownload.this, "",
"Downloading Image....", true, false);
new Thread(new Runnable() {
public void run() {
try {
 
String imageUrl = Constant.IMAGE_BASE_URL
+ File.separator + imageName;
//url and file name passing in the parameter.
String isDownloded = downloadImage(imageUrl, imageName);
if (isDownloded.equalsIgnoreCase("complete")) {
handler.sendEmptyMessage(2);
} else if (isDownloded.equalsIgnoreCase("")) {
handler.sendEmptyMessage(3);
} else {
handler.sendEmptyMessage(1);
}
} catch (Exception e) {
e.printStackTrace();
handler.sendEmptyMessage(1);
}
}
}).start();
 
}
}

For More About HttpUrlConnection class:

• http://developer.android.com/reference/java/net/HttpURLConnection.html

// image download code
public String downloadImage(String imageDownloadUrl, String imageName) {
// create directory in SDCARD
if (android.os.Environment.getExternalStorageState().equals(
android.os.Environment.MEDIA_MOUNTED))
folderName = new File(Constant.STORE_IN_FOLDER);
else
folderName = getFilesDir();
 
if (!folderName.exists())
folderName.mkdirs();
 
String response = "";
// create file name and file.
File storeImageInSDCard = new File(folderName + File.separator
+ imageName);
if (!(storeImageInSDCard.exists() && storeImageInSDCard.length() > 0)) {
// start download image
response = downloadFile(imageDownloadUrl, imageName,
folderName.toString());
}
return response;
}
 
// start download image
public String downloadFile(final String url, final String name,
String foldername) {
 
File file;
FileOutputStream os = null;
Bitmap myBitmap;
try {
URL url1 = new URL(url.replaceAll(" ", "%20"));
System.out.println("Image url :::" + url1);
HttpURLConnection urlConnection = (HttpURLConnection) url1
.openConnection();
urlConnection.setDoOutput(false);
urlConnection.setRequestMethod("GET");
urlConnection.connect();
 
// here create a file which define folder name and image name with
// extension.
file = new File(foldername, name + ".jpg");
InputStream inputStream = urlConnection.getInputStream();
byte[] buffer = new byte[1024];
int bufferLength = 0;
os = new FileOutputStream(file);
while ((bufferLength = inputStream.read(buffer)) > 0) {
os.write(buffer, 0, bufferLength);
}
 
os.flush();
os.close();
 
// if image size is too large we can scale image than download.
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
myBitmap = BitmapFactory
.decodeFile(file.getAbsolutePath(), options);
if (options.outWidth > 3000 || options.outHeight > 2000) {
options.inSampleSize = 4;
} else if (options.outWidth > 2000 || options.outHeight > 1500) {
options.inSampleSize = 3;
} else if (options.outWidth > 1000 || options.outHeight > 1000) {
options.inSampleSize = 2;
}
options.inJustDecodeBounds = false;
myBitmap = BitmapFactory
.decodeFile(file.getAbsolutePath(), options);
 
os = new FileOutputStream(file);
myBitmap.compress(CompressFormat.JPEG, 90, os);
os.flush();
os.close();
myBitmap.recycle();
 
return "complete";
} catch (SQLException e) {
e.printStackTrace();
return "error";
} catch (Exception e) {
e.printStackTrace();
return "error";
}
 
}
}

For more about BitmapFactory please refer:

• http://developer.android.com/reference/android/graphics/BitmapFactory.html

I hope you enjoy this tutorial and it would be helpful to you.

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Tejas Jasani

An entrepreneur who has founded 2 flourishing software firms in 7 years, Tejas is keen to understand everything about gaming - from the business dynamics to awesome designs to gamer psychology. As the founder-CEO of a company that has released some very successful games, he knows a thing or two about gaming. He shares his knowledge through blogs and talks that he gets invited to.