Store and use files in Assets

There are times when you probably want to your application distribution with raw resources, instead of pre-defined resources, the ‘res‘ folder, you gonna have to make use of ‘Asset‘.

‘Assets’ folder will be distributed along with the APK, which contains all the raw files you need for application, such as: text files (.txt), non-Android XML files (.xml), Audio files (.wav, .mp3, .mid)…; those cannot be put into ‘res‘ folder as usual.

Thing needed to be looked up here: AssetManager from Android Developers’ References

This class does the job that we need.

First, create a project as usual, then put files into ‘asset‘ like below:

Files in 'Assets'

Now, create a simple layout containing a TextView for displaying the content of ‘text.txt‘ and an ImageView for displaying the image ‘avatar.jpg’, which are put in Asset.

The implementation quite easy using AssetManager as mentioned above.

package pete.android.study;

import java.io.IOException;
import java.io.InputStream;

import android.app.Activity;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.widget.ImageView;
import android.widget.TextView;

public class Main extends Activity {

	ImageView mImage;
	TextView mText;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        mImage = (ImageView)findViewById(R.id.image);
        mText = (TextView)findViewById(R.id.text);
        loadDataFromAsset();
    }

    public void loadDataFromAsset() {
    	// load text
    	try {
    		// get input stream for text
	    	InputStream is = getAssets().open("text.txt");
	    	// check size
	    	int size = is.available();
	    	// create buffer for IO
	    	byte[] buffer = new byte[size];
	    	// get data to buffer
	    	is.read(buffer);
	    	// close stream
	    	is.close();
	    	// set result to TextView
	    	mText.setText(new String(buffer));
    	}
    	catch (IOException ex) {
    		return;
    	}

    	// load image
    	try {
	    	// get input stream
	    	InputStream ims = getAssets().open("avatar.jpg");
	    	// load image as Drawable
	    	Drawable d = Drawable.createFromStream(ims, null);
	    	// set image to ImageView
	    	mImage.setImageDrawable(d);
    	}
    	catch(IOException ex) {
    		return;
    	}

    }
}

That’s a quick sample code giving this result.

Read data from Asset

The distributed APK file contains the folder ‘assets‘, you might wanna check by opening it.

Quite easy, isn’t it?

@p/s: you can load image from Asset into Bitmap by using BitmapFactory.decodeStream(), instead of using Drawable.

Have fun w/ Android Coding 🙂

 

Cheers,

Pete Houston