标记与自定义图标：定义一个图标类

 var LeafIcon = L.Icon.extend({
    options: {
        shadowUrl: 'leaf-shadow.png',
        iconSize:     [38, 95],
        shadowSize:   [50, 64],
        iconAnchor:   [22, 94],
        shadowAnchor: [4, 62],
        popupAnchor:  [-3, -76]
    }
});
var greenIcon = new LeafIcon({iconUrl: 'leaf-green.png'}),
    redIcon = new LeafIcon({iconUrl: 'leaf-red.png'}),
    orangeIcon = new LeafIcon({iconUrl: 'leaf-orange.png'});
L.icon = function (options) {
    return new L.Icon(options);
};
L.marker([51.5, -0.09], {icon: greenIcon}).addTo(map).bindPopup("I am a green leaf.");
L.marker([51.495, -0.083], {icon: redIcon}).addTo(map).bindPopup("I am a red leaf.");
L.marker([51.49, -0.1], {icon: orangeIcon}).addTo(map).bindPopup("I am an orange leaf.");