[LibGDX] Screen scaling

So I started using libgdx for a while and I really really like it!
But what im missing in all of this, is the way of scaling things right!
My problem is:
-When i do a game, i do it to a default screen size, imagine 570x360, when i try to apply it, what im looking to do is resize whatever it takes so that way i would still work with the default screen size coordinates being 360 the max width and 570 max height, but i want to be able to resize whatever is on the screen to the current screen size, like drawing everything first into the 570x360 screen, but then rezise the screen.

I dont know if you are understanding what i want to do but heres an example what i used to do:

   //render image in the canvas, resizing acording to scale
   private void render() {
	BufferStrategy bufferStrategy = getBufferStrategy();
	if (bufferStrategy == null) {
		createBufferStrategy(3);
		return;
	}
	Graphics g = bufferStrategy.getDrawGraphics();
	draw((Graphics2D) image.getGraphics());
	g.drawImage(image, 0, 0, WIDTH * SCALE, HEIGHT * SCALE, null);
	g.dispose();
	bufferStrategy.show();

}

    //drawing stuff in the 570x360 BufferedImage
    public void draw(Graphics2D g) {
	g.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BICUBIC);
	g.setColor(getBackground());
	g.fillRect(0, 0, WIDTH, HEIGHT);
	stateManager.draw(g);
}

Please I really need some help on this one!