Develop Reference

How to encrypt and decrypt a pdf/doc file in Android

I am new to Android, and I am trying to encrypt and decrypt a file and want to display in Android device after decrypt.
Here I am downloading the file from the URL and storing in SD card and I don't now how to encrypt the file and then store in SD card and file size may be more then 20MB.
Code:
File downloadFile(String dwnload_file_path) {
File file = null;
try {
String extStorageDirectory = Environment.getExternalStorageDirectory().toString();
File folder = new File(extStorageDirectory, "SampleFolder");
folder.mkdir();
file = new File(folder, dest_file_path);
try{
file.createNewFile();
}catch (IOException e){
e.printStackTrace();
}
URL url = new URL(dwnload_file_path);
HttpURLConnection urlConnection = (HttpURLConnection)url.openConnection();
urlConnection.connect();
InputStream inputStream = urlConnection.getInputStream();
FileOutputStream fileOutputStream = new FileOutputStream(file);
int totalSize = urlConnection.getContentLength();
byte[] buffer = new byte[MEGABYTE];
int bufferLength = 0;
while((bufferLength = inputStream.read(buffer))>0 ){
fileOutputStream.write(buffer, 0, bufferLength);
}
fileOutputStream.close();
//ToastManager.toast(this, "Download Complete. Open PDF Application installed in the device.");
} catch (final MalformedURLException e) {
//ToastManager.toast(this, "Some error occured. Press try again.");
} catch (final IOException e) {
//ToastManager.toast(this, "Some error occured. Press try again.");
} catch (final Exception e) {
//ToastManager.toast(this, "Failed to download image. Please check your internet connection.");
}
return file;
}
Here I am displaying the file in Android device but after decrypting the file, how can I display it?
Code:
File pdfFile = new File(Environment.getExternalStorageDirectory() + "/SampleFolder/" + "Sample."pref.getString(Constants.PrefConstants.PATH_NAME));
File f = new File(pdfFile.toString());
if(f.exists()) {
Uri path = Uri.fromFile(pdfFile);
Intent pdfIntent = new Intent(Intent.ACTION_VIEW);
pdfIntent.setDataAndType(path, pref.getString(Constants.PrefConstants.PATH_NAME_APP));
//pdfIntent.setFlags(Intent. FLAG_ACTIVITY_CLEAR_TOP);
pdfIntent.setFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
startActivity(pdfIntent);
} else {
//uiManager.execute(Constants.Commands.REQGET_INSTRUCTIONS_SCREEN,null);
ToastManager.toast(getApplicationContext(), "No data available...");
}
How can I resolve this issue?

You need to use the SecretKeySpec library .
Example of encrypt method
static void encrypt() throws IOException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeyException {
// Here you read the cleartext.
FileInputStream fis = new FileInputStream("SampleFolder/yourfilename");
// This stream write the encrypted text. This stream will be wrapped by another stream.
FileOutputStream fos = new FileOutputStream("SampleFolder/yourencryptedfilename");
// Length is 16 byte
// Careful when taking user input!!! https://stackoverflow.com/a/3452620/1188357
SecretKeySpec sks = new SecretKeySpec("MyDifficultPassw".getBytes(), "AES");
// Create cipher
Cipher cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, sks);
// Wrap the output stream
CipherOutputStream cos = new CipherOutputStream(fos, cipher);
// Write bytes
int b;
byte[] d = new byte[8];
while((b = fis.read(d)) != -1) {
cos.write(d, 0, b);
}
// Flush and close streams.
cos.flush();
cos.close();
fis.close();
}
For decrypt method see the link below.
More details : How to encrypt file from SD card using AES in Android?

How to store the image in android device

I have the set of images from server.I need to store the image in device.How to do that.Can anyone guide me to store the images in android device.What is the best way to do this process.
Thanks in Advance:)

You can download image from url and store it in sd card. Whenever you want to display images then simply load that image. Here simple code for this work.
private void downloadImagesToSdCard(String downloadUrl,String imageName)
{
try{
URL url = new URL(downloadUrl); //you can write here any link
File myDir = new File("/sdcard"+"/"+Constants.imageFolder);
//Something like ("/sdcard/file.mp3")
if(!myDir.exists()){
myDir.mkdir();
Log.v("", "inside mkdir");
}
Random generator = new Random();
int n = 10000;
n = generator.nextInt(n);
String fname = imageName;
File file = new File (myDir, fname);
if (file.exists ()) file.delete ();
/* Open a connection to that URL. */
URLConnection ucon = url.openConnection();
InputStream inputStream = null;
HttpURLConnection httpConn = (HttpURLConnection)ucon;
httpConn.setRequestMethod("GET");
httpConn.connect();
if (httpConn.getResponseCode() == HttpURLConnection.HTTP_OK) {
inputStream = httpConn.getInputStream();
}
/*
* Define InputStreams to read from the URLConnection.
*/
// InputStream is = ucon.getInputStream();
/*
* Read bytes to the Buffer until there is nothing more to read(-1).
*/
FileOutputStream fos = new FileOutputStream(file);
int size = 1024*1024;
byte[] buf = new byte[size];
int byteRead;
while (((byteRead = inputStream.read(buf)) != -1)) {
fos.write(buf, 0, byteRead);
bytesDownloaded += byteRead;
}
/* Convert the Bytes read to a String. */
fos.close();
}catch(IOException io)
{
networkException = true;
continueRestore = false;
}
catch(Exception e)
{
continueRestore = false;
e.printStackTrace();
}
}
Hope this will help you.

save image in android

This is a code for saving images in SD card if and if not exist.
but i don't know how to read it.
Can anybody help me please.
This is the download file method:
public static String DownLoadFile(String netUrl, String name ) {
try {
//need uses permission WRITE_EXTERNAL_STORAGE
ByteArrayBuffer baf = null;
long startTime = 0;
//get to directory (a File object) from SD Card
File savePath=new File(Environment.getExternalStorageDirectory().getPath()+"/postImages/");
String ext="jpg";
URL url = new URL(netUrl);
//create your specific file for image storage:
File file = new File(savePath, name + "." + ext);
boolean success = true;
if (!savePath.exists()) {
success = savePath.mkdir();
}
if (success) {
if(file.createNewFile())
{
file.createNewFile();
//write the Bitmap
Log.i("file existence", "file does not exist!!!!!!!!!!!");
/* Open a connection to that URL. */
URLConnection ucon = url.openConnection();
InputStream is = ucon.getInputStream();
BufferedInputStream bis = new BufferedInputStream(is);
startTime = System.currentTimeMillis();
baf = new ByteArrayBuffer(5000);
int current = 0;
while ((current = bis.read()) != -1) {
baf.append((byte) current);
}
/* Convert the Bytes read to a String. */
FileOutputStream fos = new FileOutputStream(file);
fos.write(baf.toByteArray());
fos.flush();
fos.close();
Log.d("DownloadManager", "download ready in" + ((System.currentTimeMillis() - startTime) / 1000) + " sec");
return file.getAbsolutePath();
}//end of create file if not exists
}//end of if success
} catch (Exception exx) {
if (exx.getMessage() != null) {
} else {
}
}
return null;
}

Try this,
Uri uri = Uri.parse("file:///sdcard/temporary_file.jpg");
img.setImageURI(uri);

if u have image uri so get path from uri like
String Path = fileUri.getPath();
// read file from sdcard
public static byte[] readFromStream(String path) throws Exception { File
file = new File(path); InputStream inputStream = new
FileInputStream(file); ByteArrayOutputStream baos = new
ByteArrayOutputStream(); DataOutputStream dos = new
DataOutputStream(baos); byte[] data = new byte[(int) file.length()]; int
count = inputStream.read(data); while (count != -1) { dos.write(data, 0,
count); count = inputStream.read(data); } return baos.toByteArray(); }

android - storing image in internal storage

I an trying to store images downloaded from web to internal storage. I am refer following solution android - storing image cache in internal memory and reusing it
but still i am getting exception :
07-19 12:05:47.729: E/AndroidRuntime(341): java.lang.IllegalArgumentException: File /data/data/com.yellow.activity/files/-1717792749 contains a path separator
How to load image from filepath :
here is my code . image is an arraylist of URLs.
File fileWithinMyDir = getApplicationContext().getFilesDir();
for(int i=0; i<image.size();i++){
String filename = String.valueOf(image.get(i).hashCode());
String urlString = image.get(i);
String PATH = fileWithinMyDir.getAbsolutePath() + "/" +filename;
infoLog(PATH);
DownloadFromUrl(PATH, urlString);
img_path.add(PATH);
}
private void DownloadFromUrl(String fileName, String urlStr)
{
try
{
URL url = new URL(urlStr);
File file = new File(fileName);
URLConnection ucon = url.openConnection();
InputStream is = ucon.getInputStream();
BufferedInputStream bis = new BufferedInputStream(is);
ByteArrayBuffer baf = new ByteArrayBuffer(50);
int current = 0;
while ((current = bis.read()) != -1)
{
baf.append((byte) current);
}
FileOutputStream fos = new FileOutputStream(file,true);
fos.write(baf.toByteArray());
fos.close();
infoLog("going ryt....");
}
catch (IOException e)
{
infoLog("download "+ e.getMessage());
}
}
how to load image to imageView? I tried.
File filePath = getFileStreamPath(img_path.get(i));
imageView.setImageDrawable(Drawable.createFromPath(filePath.toString()));
but it didn't work.

To save into internal memory...
File fileWithinMyDir = getApplicationContext().getFilesDir();
try
{
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder()
.permitAll().build();
StrictMode.setThreadPolicy(policy);
URL url = new URL("http://t2.gstatic.com /images?q=tbn:ANd9GcQjZgUffqqe2mKKb5VOrDNd-ZxD7sJOU7WAHlFAy6PLbtXpyQZYdw");
File file = new File( fileWithinMyDir.getAbsolutePath() + "/" +"sun.jpg");
URLConnection ucon = url.openConnection();
InputStream is = ucon.getInputStream();
BufferedInputStream bis = new BufferedInputStream(is);
ByteArrayBuffer baf = new ByteArrayBuffer(50);
int current = 0;
while ((current = bis.read()) != -1)
{
baf.append((byte) current);
}
FileOutputStream fos = new FileOutputStream(file);
fos.write(baf.toByteArray());
fos.close();
}
catch (IOException e)
{
Log.e("download", e.getMessage());
}
To load image from internal memory..
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder()
.permitAll().build();
StrictMode.setThreadPolicy(policy);
mImgView1 = (ImageView) findViewById(R.id.mImgView1);
Bitmap bitmap = BitmapFactory.decodeFile(fileWithinMyDir.getAbsolutePath() + "/" +"sunn"+".file extension");
mImgView1.setImageBitmap(bitmap);
This is for newer android's that show error due to " android.os.networkonmainthreadexception"
u can also use AsyncTask if u want to solve the problem...

Try this way
String PATH = fileWithinMyDir.getAbsolutePath() + filename;

I solved it.
Replace following code
File filePath = getFileStreamPath(img_path.get(i));
imageView.setImageDrawable(Drawable.createFromPath(filePath.toString()));
with
imageView.setImageDrawable(Drawable.createFromPath(img_path.get(i)));

Can't download file in Android phone - Android..?

I having problem with file download,
I am able to download file in emulator but It is not working with the phone.
I have defined the permission for the Internet and write SD card.
I having one doc file on server, and if user click on download. It downloads the file. This works fine in emulator but not working in phone.
Edit
My code for download file
public void downloadFile(String _url, String fileName) {
File PATH = Environment
.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
try {
PATH.mkdirs();
URL url = new URL(_url); // you can write here any link
File file = new File(PATH, fileName);
long startTime = System.currentTimeMillis();
Log.d("Manager", "download begining");
Log.d("DownloadManager", "download url:" + url);
Log.d("DownloadManager", "downloaded file name:" + fileName);
/* Open a connection to that URL. */
URLConnection ucon = url.openConnection();
/*
* Define InputStreams to read from the URLConnection.
*/
InputStream is = ucon.getInputStream();
BufferedInputStream bis = new BufferedInputStream(is);
/*
* Read bytes to the Buffer until there is nothing more to read(-1).
*/
ByteArrayBuffer baf = new ByteArrayBuffer(50);
int current = 0;
while ((current = bis.read()) != -1) {
baf.append((byte) current);
}
/* Convert the Bytes read to a String. */
FileOutputStream fos = new FileOutputStream(file);
fos.write(baf.toByteArray());
fos.close();
Log.d("ImageManager",
"download ready in"
+ ((System.currentTimeMillis() - startTime) / 1000)
+ " sec");
} catch (IOException e) {
Log.d("ImageManager", "Error: " + e);
}
}

try the snippets given bellow...
File PATH = Environment
.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
try {
//set the download URL, a url that points to a file on the internet
//this is the file to be downloaded
_url = _url.replace(" ", "%20");
URL url = new URL(_url);
//create the new connection
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
//set up some things on the connection
urlConnection.setRequestMethod("GET");
urlConnection.setDoOutput(true);
//and connect!
urlConnection.connect();
//create a new file, specifying the path, and the filename
//which we want to save the file as.
File file = new File(PATH,fileName);
//this will be used to write the downloaded data into the file we created
FileOutputStream fileOutput = new FileOutputStream(file);
//this will be used in reading the data from the internet
InputStream inputStream = urlConnection.getInputStream();
//this is the total size of the file
int totalSize = urlConnection.getContentLength();
Log.i("Download", totalSize+"");
//variable to store total downloaded bytes
// int downloadedSize = 0;
//create a buffer...
byte[] buffer = new byte[1024];
int bufferLength = 0; //used to store a temporary size of the buffer
//now, read through the input buffer and write the contents to the file
while ( (bufferLength = inputStream.read(buffer)) > 0 ) {
//add the data in the buffer to the file in the file output stream (the file on the sd card
fileOutput.write(buffer, 0, bufferLength);
}
//close the output stream when done
fileOutput.close();
return true;
//catch some possible errors...
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
make sure you have enters the correct download path(url)