There is no default layer control control provided in the control of openlayers3.
But there are already built wheels on git, and you can use them directly. Address https://github.com/walkermatt/ol3-layerswitcher
Directly refer to the downloaded js file and css file
<link rel="stylesheet" type="text/css" href="../static/css/ol3-layerswitcher.css"> <script src="../static/js/ol3-layerswitcher.js"></script>
And add the following two lines of code to the main.js file:
var layerSwitcher = new ol.control.LayerSwitcher(); map.addControl(layerSwitcher);
After the control is loaded, as shown in the figure, the displayed layer name is the value of the title when adding the layer;
Controls are added.