@Override
    public void simpleInitApp() {
        // create a simple plane/quad
        Quad quadMesh = new Quad(1, 1);
        quadMesh.updateGeometry(1, 1, true);

        Geometry quad = new Geometry("Textured Quad", quadMesh);

        assetManager.registerLocator("https://raw.githubusercontent.com/jMonkeyEngine/BookSamples/master/assets/Textures/",
                                UrlLocator.class);
        TextureKey key = new TextureKey("mucha-window.png", false);
        key.setGenerateMips(true);
        Texture tex = assetManager.loadTexture(key);

        Material mat = new Material(assetManager, "Common/MatDefs/Misc/Unshaded.j3md");
        mat.setTexture("ColorMap", tex);
        quad.setMaterial(mat);

        float aspect = tex.getImage().getWidth() / (float) tex.getImage().getHeight();
        quad.setLocalScale(new Vector3f(aspect * 1.5f, 1.5f, 1));
        quad.center();

        rootNode.attachChild(quad);
    }
Load an image and display it from the internet using the UrlLocator.
@author Kirill Vainer
jme3-examples/src/main/java/jme3test/asset/TestUrlLoading.java