Transfer folder from Assets to Phone Storage

activity_main.xml

<?xml version="1.0" encoding="utf-8"?> 

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"     

xmlns:tools="http://schemas.android.com/tools" 

 android:layout_width="match_parent"     

android:layout_height="match_parent" 

 android:paddingBottom="@dimen/activity_vertical_margin" 

 android:paddingLeft="@dimen/activity_horizontal_margin" 

 android:paddingRight="@dimen/activity_horizontal_margin"     

android:paddingTop="@dimen/activity_vertical_margin"     

android:orientation="vertical"     

tools:context="showgallery.example.com.imagelocation2.MainActivity">

    <TextView 

 android:layout_width="wrap_content" 

 android:layout_height="wrap_content" 

 android:text="Hello World!" />
    <Button         

android:layout_width="wrap_content"         

android:layout_height="wrap_content" 

 android:text="Check for update!" 

 android:onClick="gotoUpdate"/>
</LinearLayout>

MainActivity.java

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;

public class MainActivity extends AppCompatActivity {

    AsyncTaskRunner taskRunner;
    @Override    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        taskRunner = new AsyncTaskRunner(this);
        taskRunner.execute();
    }
public void gotoUpdate(View view)
{
    taskRunner = new AsyncTaskRunner(this);
    taskRunner.execute();
}
}





AsyncTaskRunner.java





import android.app.ProgressDialog;
import android.content.Context;
import android.content.res.AssetManager;
import android.os.AsyncTask;
import android.os.Environment;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

/** * Created by pkm1 on 8/26/2016. */public  class AsyncTaskRunner extends AsyncTask<Void,String,Void> {

    ProgressDialog progressDialog;

    private Context ctx;
    public AsyncTaskRunner(Context myContext) {
        this.ctx = myContext;
    }

    @Override    protected void onPreExecute() {
        super.onPreExecute();
        progressDialog = ProgressDialog.show(ctx,"Check Update",  "Processing...");
    }

    @Override    protected Void doInBackground(Void... voids) {

        publishProgress("Processing..."); // Calls onProgressUpdate()
        try {
            copyDirorfileFromAssetManager("imagesrc", "GM/imagesrc/");
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }

    @Override    protected void onPostExecute(Void aVoid) {
        super.onPostExecute(aVoid);
        // execution of result of Long time consuming operation        progressDialog.dismiss();
    }

    public String copyDirorfileFromAssetManager(String arg_assetDir, String arg_destinationDir) throws IOException {

        System.out.print(arg_assetDir);   System.out.print(arg_destinationDir);

        File sd_path = Environment.getExternalStorageDirectory();
        String dest_dir_path = sd_path + addLeadingSlash(arg_destinationDir);
        File dest_dir = new File(dest_dir_path);

        createDir(dest_dir);

        AssetManager asset_manager = ctx.getAssets();
        String[] files = asset_manager.list(arg_assetDir);

        for (int i = 0; i < files.length; i++) {

            String abs_asset_file_path = addTrailingSlash(arg_assetDir) + files[i];
            String sub_files[] = asset_manager.list(abs_asset_file_path);

            if (sub_files.length == 0) {
                // It is a file                String dest_file_path = addTrailingSlash(dest_dir_path) + files[i];
                copyAssetFile(abs_asset_file_path, dest_file_path);
            } else {
                // It is a sub directory                copyDirorfileFromAssetManager(abs_asset_file_path, addTrailingSlash(arg_destinationDir) + files[i]);
            }
        }

        return dest_dir_path;
    }


    public void copyAssetFile(String assetFilePath, String destinationFilePath) throws IOException {
        InputStream in = ctx.getAssets().open(assetFilePath);
        OutputStream out = new FileOutputStream(destinationFilePath);

        byte[] buf = new byte[1024];
        int len;
        while ((len = in.read(buf)) > 0)
            out.write(buf, 0, len);
        in.close();
        out.close();
    }

    public String addTrailingSlash(String path) {
        if (path.charAt(path.length() - 1) != '/') {
            path += "/";
        }
        return path;
    }

    public String addLeadingSlash(String path) {
        if (path.charAt(0) != '/') {
            path = "/" + path;
        }
        return path;
    }

    public void createDir(File dir) throws IOException {
        if (dir.exists()) {
            if (!dir.isDirectory()) {
                throw new IOException("Can't create directory, a file is in the way");
            }
        } else {
            dir.mkdirs();
            if (!dir.isDirectory()) {
                throw new IOException("Unable to create directory");
            }
        }
    }
}