Develop Reference

How to make a downloaded file visible in File Manager after written/downloaded into Android?

I have successfully downloaded the file from the server and saved it on Android storage, but the file is stored in a deep path, for example: /storage/emulated/0/Android/data/example.com.yourapp/files/Download/example_file.pdf
The code I'm currently using is like this:
private boolean writeResponseBodyToDisk(ResponseBody body) {
try {
File filesDir = getContext().getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS);
assert filesDir != null;
downloadedFile = new File(filesDir,
"file_name" + ".pdf");
InputStream inputStream = null;
OutputStream outputStream = null;
try {
byte[] fileReader = new byte[4096];
long fileSize = body.contentLength();
long fileSizeDownloaded = 0;
inputStream = body.byteStream();
outputStream = new FileOutputStream(downloadedFile);
while (true) {
int read = inputStream.read(fileReader);
if (read == -1) {
break;
}
outputStream.write(fileReader, 0, read);
fileSizeDownloaded += read;
}
outputStream.flush();
Functions.scanFile(getContext(), downloadedFile, "application/pdf");
return true;
} catch (IOException e) {
return false;
} finally {
if (inputStream != null) {
inputStream.close();
}
if (outputStream != null) {
outputStream.close();
}
}
} catch (IOException e) {
return false;
}
}
What I want, when the download process is successful and I open the file manager, the latest file that already downloaded can be seen in the latest file before.
I don't know yet, but I think I need to make use of MediaStore to make my files visible in File Manager by trying this code:
public static void scanFile(Context ctxt, File f, String mimeType) {
MediaScannerConnection.scanFile(ctxt, new String[] {f.getAbsolutePath()}, new String[] {mimeType}, null);
}
But it didn't work either. How do i achieve this?

So i just change File filesDir = getContext().getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS);
into File filesDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
And it's available in recent files in File manager

Why can't i open pdf file from device storage?

I am saving a pdf file that im am receiving from server via method:
private boolean writeResponseBodyToDisk(ResponseBody body) {
try {
File futureStudioIconFile = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS), "order.pdf");
InputStream inputStream = null;
OutputStream outputStream = null;
try {
byte[] fileReader = new byte[4096];
long fileSize = body.contentLength();
long fileSizeDownloaded = 0;
inputStream = body.byteStream();
outputStream = new FileOutputStream(futureStudioIconFile);
while (true) {
int read = inputStream.read(fileReader);
if (read == -1) {
break;
}
outputStream.write(fileReader, 0, read);
fileSizeDownloaded += read;
Log.d(TAG, "file download: " + fileSizeDownloaded + " of " + fileSize);
}
outputStream.flush();
return true;
} catch (IOException e) {
return false;
} finally {
if (inputStream != null) {
inputStream.close();
}
if (outputStream != null) {
outputStream.close();
}
}
} catch (IOException e) {
return false;
}
}
I did manage to save it on the device though as much as i understood i can't open it directly after the download because it's downloading from a item click in a adapter. Anyway, I made it so that after the download it changes the page to another activity where i should be able to open it, though it still fails. Code I am using in the activity:
String path = getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS) + "/order.pdf";
File file=new File(path);
if(file.canRead())
{
pdfView.fromFile(file).defaultPage(1).onLoad(new OnLoadCompleteListener() {
#Override
public void loadComplete(int nbPages) {
Toast.makeText(PdfActivity.this, String.valueOf(nbPages), Toast.LENGTH_LONG).show();
}
}).load();
}
Since the code should be correct, I tried a lot of variations of getting the path to the pdf, none seemed to work. Is the issue in the path or is it a whole other problem?
Edit: It can't read the file in if(file.canRead())

Android:How to Copy a Folder From 'assets' Includes files and folders to sdcard [duplicate]

I'm trying to use a directory that I have in my assets folder and access it as a File. Is it possible to access something in the Assets directory as a File? If not, how can I copy a directory from the Assets folder to the application's local directory?
I would copy a file like so:
try
{
InputStream stream = this.getAssets().open("myFile");
OutputStream output = new BufferedOutputStream(new FileOutputStream(this.getFilesDir() + "/myNewFile"));
byte data[] = new byte[1024];
int count;
while((count = stream.read(data)) != -1)
{
output.write(data, 0, count);
}
output.flush();
output.close();
stream.close();
}
catch(IOException e)
{
e.printStackTrace();
}
However, I'm not sure how I would be able to do this for a directory.
I would rather not build my infrastructure around something that doesn't work, so how would I copy a directory from Assets to a local directory, or is it possible to access a directory in my Assets as a File?
EDIT
This is how I solved it for my own project:
InputStream stream = null;
OutputStream output = null;
for(String fileName : this.getAssets().list("demopass"))
{
stream = this.getAssets().open("directoryName/" + fileName);
output = new BufferedOutputStream(new FileOutputStream(this.getFilesDir() + "/newDirectory/" + fileName));
byte data[] = new byte[1024];
int count;
while((count = stream.read(data)) != -1)
{
output.write(data, 0, count);
}
output.flush();
output.close();
stream.close();
stream = null;
output = null;
}

As suggested by dmaxi in comment above, you can use his link, with this code:
void displayFiles (AssetManager mgr, String path) {
try {
String list[] = mgr.list(path);
if (list != null)
for (int i=0; i<list.length; ++i)
{
Log.v("Assets:", path +"/"+ list[i]);
displayFiles(mgr, path + "/" + list[i]);
}
} catch (IOException e) {
Log.v("List error:", "can't list" + path);
}
}
I took it on this link.
Maybe you can combine this code with precedent one.
EDIT: see also AssetManager.
private void copyFolder(String name) {
// "Name" is the name of your folder!
AssetManager assetManager = getAssets();
String[] files = null;
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state)) {
// We can read and write the media
// Checking file on assets subfolder
try {
files = assetManager.list(name);
} catch (IOException e) {
Log.e("ERROR", "Failed to get asset file list.", e);
}
// Analyzing all file on assets subfolder
for(String filename : files) {
InputStream in = null;
OutputStream out = null;
// First: checking if there is already a target folder
File folder = new File(Environment.getExternalStorageDirectory() + "/yourTargetFolder/" + name);
boolean success = true;
if (!folder.exists()) {
success = folder.mkdir();
}
if (success) {
// Moving all the files on external SD
try {
in = assetManager.open(name + "/" +filename);
out = new FileOutputStream(Environment.getExternalStorageDirectory() + "/yourTargetFolder/" + name + "/" + filename);
Log.i("WEBVIEW", Environment.getExternalStorageDirectory() + "/yourTargetFolder/" + name + "/" + filename);
copyFile(in, out);
in.close();
in = null;
out.flush();
out.close();
out = null;
} catch(IOException e) {
Log.e("ERROR", "Failed to copy asset file: " + filename, e);
} finally {
// Edit 3 (after MMs comment)
in.close();
in = null;
out.flush();
out.close();
out = null;
}
}
else {
// Do something else on failure
}
}
} else if (Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
// We can only read the media
} else {
// Something else is wrong. It may be one of many other states, but all we need
// is to know is we can neither read nor write
}
}
// Method used by copyAssets() on purpose to copy a file.
private void copyFile(InputStream in, OutputStream out) throws IOException {
byte[] buffer = new byte[1024];
int read;
while((read = in.read(buffer)) != -1) {
out.write(buffer, 0, read);
}
}
EDIT 2: i'have added an example above: this piece of code copy only a specific folder from assets, to sd card. Let me know if it works!

Here is a recursive function to do this - copyAssetFolder.
public static boolean copyAssetFolder(Context context, String srcName, String dstName) {
try {
boolean result = true;
String fileList[] = context.getAssets().list(srcName);
if (fileList == null) return false;
if (fileList.length == 0) {
result = copyAssetFile(context, srcName, dstName);
} else {
File file = new File(dstName);
result = file.mkdirs();
for (String filename : fileList) {
result &= copyAssetFolder(context, srcName + File.separator + filename, dstName + File.separator + filename);
}
}
return result;
} catch (IOException e) {
e.printStackTrace();
return false;
}
}
public static boolean copyAssetFile(Context context, String srcName, String dstName) {
try {
InputStream in = context.getAssets().open(srcName);
File outFile = new File(dstName);
OutputStream out = new FileOutputStream(outFile);
byte[] buffer = new byte[1024];
int read;
while ((read = in.read(buffer)) != -1) {
out.write(buffer, 0, read);
}
in.close();
out.close();
return true;
} catch (IOException e) {
e.printStackTrace();
return false;
}
}
Or the same in Kotlin
fun AssetManager.copyAssetFolder(srcName: String, dstName: String): Boolean {
return try {
var result = true
val fileList = this.list(srcName) ?: return false
if (fileList.isEmpty()) {
result = copyAssetFile(srcName, dstName)
} else {
val file = File(dstName)
result = file.mkdirs()
for (filename in fileList) {
result = result and copyAssetFolder(
srcName + separator.toString() + filename,
dstName + separator.toString() + filename
)
}
}
result
} catch (e: IOException) {
e.printStackTrace()
false
}
}
fun AssetManager.copyAssetFile(srcName: String, dstName: String): Boolean {
return try {
val inStream = this.open(srcName)
val outFile = File(dstName)
val out: OutputStream = FileOutputStream(outFile)
val buffer = ByteArray(1024)
var read: Int
while (inStream.read(buffer).also { read = it } != -1) {
out.write(buffer, 0, read)
}
inStream.close()
out.close()
true
} catch (e: IOException) {
e.printStackTrace()
false
}
}

You can use following method for copying your asset folder to a location in your SD Card. From your calling method just call moveAssetToStorageDir("") for moving entire asset folder. In case of sub folders you can specify the relative path inside the asset folder.
public void moveAssetToStorageDir(String path){
File file = getExternalFilesDir(null);
String rootPath = file.getPath() + "/" + path;
try{
String [] paths = getAssets().list(path);
for(int i=0; i<paths.length; i++){
if(paths[i].indexOf(".")==-1){
File dir = new File(rootPath + paths[i]);
dir.mkdir();
moveAssetToStorageDir(paths[i]);
}else {
File dest = null;
InputStream in = null;
if(path.length() == 0) {
dest = new File(rootPath + paths[i]);
in = getAssets().open(paths[i]);
}else{
dest = new File(rootPath + "/" + paths[i]);
in = getAssets().open(path + "/" + paths[i]);
}
dest.createNewFile();
FileOutputStream out = new FileOutputStream(dest);
byte [] buff = new byte[in.available()];
in.read(buff);
out.write(buff);
out.close();
in.close();
}
}
}catch (Exception exp){
exp.printStackTrace();
}
}

Here is the clean version of the OP's answer.
public void copyAssetFolderToFolder(Context activity, String assetsFolder, File destinationFolder) {
InputStream stream = null;
OutputStream output = null;
try {
for (String fileName : activity.getAssets().list(assetsFolder)) {
stream = activity.getAssets().open(assetsFolder + ((assetsFolder.endsWith(File.pathSeparator))?"":File.pathSeparator) + fileName);
output = new BufferedOutputStream(new FileOutputStream(new File(destinationFolder, fileName)));
byte data[] = new byte[1024];
int count;
while ((count = stream.read(data)) != -1) {
output.write(data, 0, count);
}
output.flush();
output.close();
stream.close();
stream = null;
output = null;
}
} catch (/*any*/Exception e){e.printStackTrace();}
}
For future reference, please save everyone the trouble and post contextually complete source listings. This site can be a great coding resource for beginners and experts, if only you would post complete answers. One cannot assume that anyone else "understands" where a random block of code belongs, or the context that the code is supposed to be executed within.
This sample calls for the context of an activity, which houses the getAssets() method. Within the android platform, their are other classes besides Activity which can supply this context. One example is the (generic reference) Service class.

Moving an arbitrary folder of directories and files from Assets
The thing is... Assets are special. You cannot wrap it in a File object and ask isDirectory() and you cannot pass these assets into the NDK. So it is better to wrap them up and move them to a cache directory or onto the SDCard which is why you're here.
I've seen many SO answers that involve some version of rolling through an array of fileOrDirectoryName strings and then creating directories followed by a recursive call and copying individual files. Which leads you to create a folder or file and you cannot tell from an asset which you have.
Make it a Zip file
My recommendation is to take each arbitrary collection of assets that you want to ship to the SDCard or an internal cache folder and Zip it up. The problem is structured in an way more compatible with the Assets concept.
AssetManager assetManager = context.getAssets();
String fullAssetPath = fromAssetPath + "/" + zipFilename;
String toPath = "/wherever/I/want";
try {
InputStream inputStream = assetManager.open(fullAssetPath);
ZipInputStream zipInputStream = new ZipInputStream(new BufferedInputStream(inputStream));
ZipEntry zipEntry;
byte[] buffer = new byte[8192];
while ((zipEntry = zipInputStream.getNextEntry()) != null) {
String fileOrDirectory = zipEntry.getName();
Uri.Builder builder = new Uri.Builder();
builder.scheme("file");
builder.appendPath(toPath);
builder.appendPath(fileOrDirectory);
String fullToPath = builder.build().getPath();
if (zipEntry.isDirectory()) {
File directory = new File(fullToPath);
directory.mkdirs();
continue;
}
FileOutputStream fileOutputStream = new FileOutputStream(fullToPath);
while ((count = zipInputStream.read(buffer)) != -1) {
fileOutputStream.write(buffer, 0, count);
}
fileOutputStream.close();
zipInputStream.closeEntry();
}
zipInputStream.close();
} catch (IOException e) {
Log.e(TAG, e.getLocalizedMessage());
}
Small note about buffer sizes
I've seen a lot of examples involving very small buffer sizes, for example 1024. Unless you just want to waste time feel free to try larger byte buffer sizes. Even my choice of 8192 is probably small on modern hardware.
Avoiding Stringy paths
Notice the use of Uri.Builder to construct the path. I much prefer this style of path construction over directory + "/" + file. Then you're in the business, for the sake of consistency avoiding assigning String d = "myDirectory/" or String f = "/file.txt" and other such string hacking nonsense.

Here's a recursive solution written in kotlin. It works with both files and dirs.
Usage - copyAssetDir(context, "<asset path>", "<dest dir>")
import android.content.Context
import java.io.File
import java.io.FileOutputStream
fun copyAssetDir(context: Context, assetPath: String, destDirPath: String) {
walkAssetDir(context, assetPath) {
copyAssetFile(context, it, "$destDirPath/$it")
}
}
fun walkAssetDir(context: Context, assetPath: String, callback: ((String) -> Unit)) {
val children = context.assets.list(assetPath) ?: return
if (children.isEmpty()) {
callback(assetPath)
} else {
for (child in children) {
walkAssetDir(context, "$assetPath/$child", callback)
}
}
}
fun copyAssetFile(context: Context, assetPath: String, destPath: String): File {
val destFile = File(destPath)
File(destFile.parent).mkdirs()
destFile.createNewFile()
context.assets.open(assetPath).use { src ->
FileOutputStream(destFile).use { dest ->
src.copyTo(dest)
}
}
return destFile
}

This is code for copy assets folder with directory and files both copy into sdcard folder...
this one works perfectly for me...
public void copyFileOrDir(String path) {
AssetManager assetManager = this.getAssets();
String assets[] = null;
try {
assets = assetManager.list(path);
if (assets.length == 0) {
copyFile(path);
} else {
String fullPath = "/data/data/" + this.getPackageName() + "/" + path;
File dir = new File(fullPath);
if (!dir.exists())
dir.mkdir();
for (int i = 0; i < assets.length; ++i) {
copyFileOrDir(path + "/" + assets[i]);
}
}
} catch (IOException ex) {
Log.e("tag", "I/O Exception", ex);
}
}
private void copyFile(String filename) {
AssetManager assetManager = this.getAssets();
InputStream in = null;
OutputStream out = null;
try {
in = assetManager.open(filename);
String newFileName = "/data/data/" + this.getPackageName() + "/" + filename;
out = new FileOutputStream(newFileName);
byte[] buffer = new byte[1024];
int read;
while ((read = in.read(buffer)) != -1) {
out.write(buffer, 0, read);
}
in.close();
in = null;
out.flush();
out.close();
out = null;
} catch (Exception e) {
Log.e("tag", e.getMessage());
}
}

how to install an app from internal storage files

I'm trying to download an apk file then install it.
I have done it with an external storage directory but when I download the file in a Local directory I can't parse it.
Here is the code on OnCreate method
final DownloadTask downloadTask = new DownloadTask(this);
downloadTask.execute("http://file.appsapk.com/wp-content/uploads/apps-2/Gmail.apk","Gmail.apk");
DownloadTask is a class that extends from AsyncTask.
Here is the background task:
#Override
protected String doInBackground(String... sUrl) {
file_name=sUrl[1];
Boolean isSDPresent = android.os.Environment.getExternalStorageState().equals(android.os.Environment.MEDIA_MOUNTED);
if (isSDPresent) {
directory = new File(Environment.getExternalStorageDirectory()+File.separator+"app_directory");
}
else
{
directory = getFilesDir();
}
if (!directory.exists())
directory.mkdirs();
InputStream input = null;
OutputStream output = null;
HttpURLConnection connection = null;
try {
URL url = new URL(sUrl[0]);
connection = (HttpURLConnection) url.openConnection();
connection.connect();
if (connection.getResponseCode() != HttpURLConnection.HTTP_OK) {
return "Server returned HTTP " + connection.getResponseCode()
+ " " + connection.getResponseMessage();
}
int fileLength = connection.getContentLength();
input = connection.getInputStream();
output = new FileOutputStream(directory+"/"+file_name);
byte[] buffer = new byte[1024];
long total = 0;
int count;
while ((count = input.read(buffer)) != -1) {
if (isCancelled()) {
input.close();
return null;
}
total += count;
if (fileLength > 0) // only if total length is known
publishProgress((int) (total * 100 / fileLength));
output.write(buffer, 0, count);
}
} catch (Exception e) {
return e.toString();
} finally {
try {
if (input != null)
input.close();
if (output != null)
output.close();
} catch (IOException ignored) {
}
if (connection != null)
connection.disconnect();
}
return null;
}
And this is the post execution method that runs after the first one done downloading the file:
#Override
protected void onPostExecute(String result) {
mWakeLock.release();
mProgressDialog.dismiss();
if (result != null)
{
Toast.makeText(context,"Download error: "+result, Toast.LENGTH_LONG).show();
}
else
{
Toast.makeText(context, "File downloaded", Toast.LENGTH_SHORT).show();
File file = new File(directory, file_name);
Intent promptInstall = new Intent(Intent.ACTION_VIEW)
.setDataAndType(Uri.fromFile(file),
"application/vnd.android.package-archive");
context.startActivity(promptInstall);
finish();
}
It runs perfectly with an external storage but it won't run with an external one. Why not?

Try to use openfileoutput() rather than OutputStream in saving your file in internal storage and allow it to be readable. http://developer.android.com/guide/topics/data/data-storage.html#filesInternal . The package error is mainly caused by the permission of internal storage.

It's because of android application can not read from another application file if it is written using PRIVATE mode.So you have to change the mode of the file. i have just modify else part of your onPostExecute() method below.
try {
String tempfile="xyzfile";
File file = new File(directory, file_name);
FileInputStream inStream = new FileInputStream(file);
FileOutputStream fos = context.openFileOutput(tempfile,
context.MODE_WORLD_WRITEABLE | context.MODE_WORLD_READABLE);
byte[] buffer = new byte[1024];
int length;
// copy the file content in bytes
while ((length = inStream.read(buffer)) > 0) {
fos.write(buffer, 0, length);
}
inStream.close();
fos.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
File file = new File(context.getFilesDir(), tempfile);
Intent promptInstall = new Intent(Intent.ACTION_VIEW).setDataAndType(
Uri.fromFile(file), "application/vnd.android.package-archive");
context.startActivity(promptInstall);

Copy directory from Assets to local directory

I'm trying to use a directory that I have in my assets folder and access it as a File. Is it possible to access something in the Assets directory as a File? If not, how can I copy a directory from the Assets folder to the application's local directory?
I would copy a file like so:
try
{
InputStream stream = this.getAssets().open("myFile");
OutputStream output = new BufferedOutputStream(new FileOutputStream(this.getFilesDir() + "/myNewFile"));
byte data[] = new byte[1024];
int count;
while((count = stream.read(data)) != -1)
{
output.write(data, 0, count);
}
output.flush();
output.close();
stream.close();
}
catch(IOException e)
{
e.printStackTrace();
}
However, I'm not sure how I would be able to do this for a directory.
I would rather not build my infrastructure around something that doesn't work, so how would I copy a directory from Assets to a local directory, or is it possible to access a directory in my Assets as a File?
EDIT
This is how I solved it for my own project:
InputStream stream = null;
OutputStream output = null;
for(String fileName : this.getAssets().list("demopass"))
{
stream = this.getAssets().open("directoryName/" + fileName);
output = new BufferedOutputStream(new FileOutputStream(this.getFilesDir() + "/newDirectory/" + fileName));
byte data[] = new byte[1024];
int count;
while((count = stream.read(data)) != -1)
{
output.write(data, 0, count);
}
output.flush();
output.close();
stream.close();
stream = null;
output = null;
}

As suggested by dmaxi in comment above, you can use his link, with this code:
void displayFiles (AssetManager mgr, String path) {
try {
String list[] = mgr.list(path);
if (list != null)
for (int i=0; i<list.length; ++i)
{
Log.v("Assets:", path +"/"+ list[i]);
displayFiles(mgr, path + "/" + list[i]);
}
} catch (IOException e) {
Log.v("List error:", "can't list" + path);
}
}
I took it on this link.
Maybe you can combine this code with precedent one.
EDIT: see also AssetManager.
private void copyFolder(String name) {
// "Name" is the name of your folder!
AssetManager assetManager = getAssets();
String[] files = null;
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state)) {
// We can read and write the media
// Checking file on assets subfolder
try {
files = assetManager.list(name);
} catch (IOException e) {
Log.e("ERROR", "Failed to get asset file list.", e);
}
// Analyzing all file on assets subfolder
for(String filename : files) {
InputStream in = null;
OutputStream out = null;
// First: checking if there is already a target folder
File folder = new File(Environment.getExternalStorageDirectory() + "/yourTargetFolder/" + name);
boolean success = true;
if (!folder.exists()) {
success = folder.mkdir();
}
if (success) {
// Moving all the files on external SD
try {
in = assetManager.open(name + "/" +filename);
out = new FileOutputStream(Environment.getExternalStorageDirectory() + "/yourTargetFolder/" + name + "/" + filename);
Log.i("WEBVIEW", Environment.getExternalStorageDirectory() + "/yourTargetFolder/" + name + "/" + filename);
copyFile(in, out);
in.close();
in = null;
out.flush();
out.close();
out = null;
} catch(IOException e) {
Log.e("ERROR", "Failed to copy asset file: " + filename, e);
} finally {
// Edit 3 (after MMs comment)
in.close();
in = null;
out.flush();
out.close();
out = null;
}
}
else {
// Do something else on failure
}
}
} else if (Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
// We can only read the media
} else {
// Something else is wrong. It may be one of many other states, but all we need
// is to know is we can neither read nor write
}
}
// Method used by copyAssets() on purpose to copy a file.
private void copyFile(InputStream in, OutputStream out) throws IOException {
byte[] buffer = new byte[1024];
int read;
while((read = in.read(buffer)) != -1) {
out.write(buffer, 0, read);
}
}
EDIT 2: i'have added an example above: this piece of code copy only a specific folder from assets, to sd card. Let me know if it works!

Here is a recursive function to do this - copyAssetFolder.
public static boolean copyAssetFolder(Context context, String srcName, String dstName) {
try {
boolean result = true;
String fileList[] = context.getAssets().list(srcName);
if (fileList == null) return false;
if (fileList.length == 0) {
result = copyAssetFile(context, srcName, dstName);
} else {
File file = new File(dstName);
result = file.mkdirs();
for (String filename : fileList) {
result &= copyAssetFolder(context, srcName + File.separator + filename, dstName + File.separator + filename);
}
}
return result;
} catch (IOException e) {
e.printStackTrace();
return false;
}
}
public static boolean copyAssetFile(Context context, String srcName, String dstName) {
try {
InputStream in = context.getAssets().open(srcName);
File outFile = new File(dstName);
OutputStream out = new FileOutputStream(outFile);
byte[] buffer = new byte[1024];
int read;
while ((read = in.read(buffer)) != -1) {
out.write(buffer, 0, read);
}
in.close();
out.close();
return true;
} catch (IOException e) {
e.printStackTrace();
return false;
}
}
Or the same in Kotlin
fun AssetManager.copyAssetFolder(srcName: String, dstName: String): Boolean {
return try {
var result = true
val fileList = this.list(srcName) ?: return false
if (fileList.isEmpty()) {
result = copyAssetFile(srcName, dstName)
} else {
val file = File(dstName)
result = file.mkdirs()
for (filename in fileList) {
result = result and copyAssetFolder(
srcName + separator.toString() + filename,
dstName + separator.toString() + filename
)
}
}
result
} catch (e: IOException) {
e.printStackTrace()
false
}
}
fun AssetManager.copyAssetFile(srcName: String, dstName: String): Boolean {
return try {
val inStream = this.open(srcName)
val outFile = File(dstName)
val out: OutputStream = FileOutputStream(outFile)
val buffer = ByteArray(1024)
var read: Int
while (inStream.read(buffer).also { read = it } != -1) {
out.write(buffer, 0, read)
}
inStream.close()
out.close()
true
} catch (e: IOException) {
e.printStackTrace()
false
}
}

You can use following method for copying your asset folder to a location in your SD Card. From your calling method just call moveAssetToStorageDir("") for moving entire asset folder. In case of sub folders you can specify the relative path inside the asset folder.
public void moveAssetToStorageDir(String path){
File file = getExternalFilesDir(null);
String rootPath = file.getPath() + "/" + path;
try{
String [] paths = getAssets().list(path);
for(int i=0; i<paths.length; i++){
if(paths[i].indexOf(".")==-1){
File dir = new File(rootPath + paths[i]);
dir.mkdir();
moveAssetToStorageDir(paths[i]);
}else {
File dest = null;
InputStream in = null;
if(path.length() == 0) {
dest = new File(rootPath + paths[i]);
in = getAssets().open(paths[i]);
}else{
dest = new File(rootPath + "/" + paths[i]);
in = getAssets().open(path + "/" + paths[i]);
}
dest.createNewFile();
FileOutputStream out = new FileOutputStream(dest);
byte [] buff = new byte[in.available()];
in.read(buff);
out.write(buff);
out.close();
in.close();
}
}
}catch (Exception exp){
exp.printStackTrace();
}
}

Here is the clean version of the OP's answer.
public void copyAssetFolderToFolder(Context activity, String assetsFolder, File destinationFolder) {
InputStream stream = null;
OutputStream output = null;
try {
for (String fileName : activity.getAssets().list(assetsFolder)) {
stream = activity.getAssets().open(assetsFolder + ((assetsFolder.endsWith(File.pathSeparator))?"":File.pathSeparator) + fileName);
output = new BufferedOutputStream(new FileOutputStream(new File(destinationFolder, fileName)));
byte data[] = new byte[1024];
int count;
while ((count = stream.read(data)) != -1) {
output.write(data, 0, count);
}
output.flush();
output.close();
stream.close();
stream = null;
output = null;
}
} catch (/*any*/Exception e){e.printStackTrace();}
}
For future reference, please save everyone the trouble and post contextually complete source listings. This site can be a great coding resource for beginners and experts, if only you would post complete answers. One cannot assume that anyone else "understands" where a random block of code belongs, or the context that the code is supposed to be executed within.
This sample calls for the context of an activity, which houses the getAssets() method. Within the android platform, their are other classes besides Activity which can supply this context. One example is the (generic reference) Service class.

Moving an arbitrary folder of directories and files from Assets
The thing is... Assets are special. You cannot wrap it in a File object and ask isDirectory() and you cannot pass these assets into the NDK. So it is better to wrap them up and move them to a cache directory or onto the SDCard which is why you're here.
I've seen many SO answers that involve some version of rolling through an array of fileOrDirectoryName strings and then creating directories followed by a recursive call and copying individual files. Which leads you to create a folder or file and you cannot tell from an asset which you have.
Make it a Zip file
My recommendation is to take each arbitrary collection of assets that you want to ship to the SDCard or an internal cache folder and Zip it up. The problem is structured in an way more compatible with the Assets concept.
AssetManager assetManager = context.getAssets();
String fullAssetPath = fromAssetPath + "/" + zipFilename;
String toPath = "/wherever/I/want";
try {
InputStream inputStream = assetManager.open(fullAssetPath);
ZipInputStream zipInputStream = new ZipInputStream(new BufferedInputStream(inputStream));
ZipEntry zipEntry;
byte[] buffer = new byte[8192];
while ((zipEntry = zipInputStream.getNextEntry()) != null) {
String fileOrDirectory = zipEntry.getName();
Uri.Builder builder = new Uri.Builder();
builder.scheme("file");
builder.appendPath(toPath);
builder.appendPath(fileOrDirectory);
String fullToPath = builder.build().getPath();
if (zipEntry.isDirectory()) {
File directory = new File(fullToPath);
directory.mkdirs();
continue;
}
FileOutputStream fileOutputStream = new FileOutputStream(fullToPath);
while ((count = zipInputStream.read(buffer)) != -1) {
fileOutputStream.write(buffer, 0, count);
}
fileOutputStream.close();
zipInputStream.closeEntry();
}
zipInputStream.close();
} catch (IOException e) {
Log.e(TAG, e.getLocalizedMessage());
}
Small note about buffer sizes
I've seen a lot of examples involving very small buffer sizes, for example 1024. Unless you just want to waste time feel free to try larger byte buffer sizes. Even my choice of 8192 is probably small on modern hardware.
Avoiding Stringy paths
Notice the use of Uri.Builder to construct the path. I much prefer this style of path construction over directory + "/" + file. Then you're in the business, for the sake of consistency avoiding assigning String d = "myDirectory/" or String f = "/file.txt" and other such string hacking nonsense.

Here's a recursive solution written in kotlin. It works with both files and dirs.
Usage - copyAssetDir(context, "<asset path>", "<dest dir>")
import android.content.Context
import java.io.File
import java.io.FileOutputStream
fun copyAssetDir(context: Context, assetPath: String, destDirPath: String) {
walkAssetDir(context, assetPath) {
copyAssetFile(context, it, "$destDirPath/$it")
}
}
fun walkAssetDir(context: Context, assetPath: String, callback: ((String) -> Unit)) {
val children = context.assets.list(assetPath) ?: return
if (children.isEmpty()) {
callback(assetPath)
} else {
for (child in children) {
walkAssetDir(context, "$assetPath/$child", callback)
}
}
}
fun copyAssetFile(context: Context, assetPath: String, destPath: String): File {
val destFile = File(destPath)
File(destFile.parent).mkdirs()
destFile.createNewFile()
context.assets.open(assetPath).use { src ->
FileOutputStream(destFile).use { dest ->
src.copyTo(dest)
}
}
return destFile
}

This is code for copy assets folder with directory and files both copy into sdcard folder...
this one works perfectly for me...
public void copyFileOrDir(String path) {
AssetManager assetManager = this.getAssets();
String assets[] = null;
try {
assets = assetManager.list(path);
if (assets.length == 0) {
copyFile(path);
} else {
String fullPath = "/data/data/" + this.getPackageName() + "/" + path;
File dir = new File(fullPath);
if (!dir.exists())
dir.mkdir();
for (int i = 0; i < assets.length; ++i) {
copyFileOrDir(path + "/" + assets[i]);
}
}
} catch (IOException ex) {
Log.e("tag", "I/O Exception", ex);
}
}
private void copyFile(String filename) {
AssetManager assetManager = this.getAssets();
InputStream in = null;
OutputStream out = null;
try {
in = assetManager.open(filename);
String newFileName = "/data/data/" + this.getPackageName() + "/" + filename;
out = new FileOutputStream(newFileName);
byte[] buffer = new byte[1024];
int read;
while ((read = in.read(buffer)) != -1) {
out.write(buffer, 0, read);
}
in.close();
in = null;
out.flush();
out.close();
out = null;
} catch (Exception e) {
Log.e("tag", e.getMessage());
}
}