Android - Copy files from assets to /data/data folder

Question

I need to use some files in my app. They are kept in asset folder. I saw discussions on SO, where the files are being copied from asset folder, to /data/data/<package_name> on the internal storage, and then being used. I get the code, but what I do not get is, what is the need to copy the assets to internal storage?

Gymkhana

see this – Neibart

@Neibart I get it how we can copy assets to internal storage or external storage. I get both are possible, eg, here is some sample code for copying file from asset to internal storage - #15575483. What I don't get is, why would one want to do that. What is the significance of copying asset to internal/external storage. – Gymkhana

Answer 1

Try this:(Use all three method its work for me and assign destination path in "toPath" string object)

  String toPath = "/data/data/" + getPackageName();  // Your application path


   private static boolean copyAssetFolder(AssetManager assetManager,
            String fromAssetPath, String toPath) {
        try {
            String[] files = assetManager.list(fromAssetPath);
            new File(toPath).mkdirs();
            boolean res = true;
            for (String file : files)
                if (file.contains("."))
                    res &= copyAsset(assetManager, 
                            fromAssetPath + "/" + file,
                            toPath + "/" + file);
                else 
                    res &= copyAssetFolder(assetManager, 
                            fromAssetPath + "/" + file,
                            toPath + "/" + file);
            return res;
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        }
    }

    private static boolean copyAsset(AssetManager assetManager,
            String fromAssetPath, String toPath) {
        InputStream in = null;
        OutputStream out = null;
        try {
          in = assetManager.open(fromAssetPath);
          new File(toPath).createNewFile();
          out = new FileOutputStream(toPath);
          copyFile(in, out);
          in.close();
          in = null;
          out.flush();
          out.close();
          out = null;
          return true;
        } catch(Exception e) {
            e.printStackTrace();
            return false;
        }
    }

    private static 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);
        }
    }

Induct

Right idea, but you should not hard code the /data directory (as it is subject to change) but rather discover it via the appropriate api at runtime. – Taxi

Its depend on user , I was provide answer for copying asset folder to some path..and if you read question again user ask for "/data/data" clearly. – Induct

@LavekushAgrawal this code will copy to "/data/data/" + getPackageName()... this is not exactly /data/data/. – Nonconformist

@Nonconformist Can you please edit my answer accordingly please, it will help to other ones. thank you. – Induct

Where is the implementation for the assetFolder method? – Legaspi

Why not use the <application Context>getFilesDir() method instead of the "/data/data/<package name>"? – Expense

I did this and got permission denied when trying to execute the binary asset – Studley

Answer 2

One reason that just popped up for me is when using existing C/C++ code with NDK that requires a path to a file and you don't want to modify that code.

For example, I'm using an existing C library that needs some data files and the only existing interface is some "load( char* path )" function.

Perhaps there is actually some better method but I have not found any yet.

Ceto

Answer 3

public final String path = "/data/data/com.aliserver.shop/databases/";
public final String Name = "store_db";

public void _copydatabase() throws IOException {

        OutputStream myOutput = new FileOutputStream(path + Name);
        byte[] buffer = new byte[1024];
        int length;
        InputStream myInput = MyContext.getAssets().open("store_db");
        while ((length = myInput.read(buffer)) > 0) {
            myOutput.write(buffer, 0, length);
        }
        myInput.close();
        myOutput.flush();
        myOutput.close();

    }

Lys

Answer 4

I think you can't edit/modify data in asset folder in run time or after application installed .So we move files into internal folder then start working on it.

Shake