在谷歌地图 api v2 中很容易，

var map = new GMap2(document.getElementById("map"));
    map.setCenter(new GLatLng(53.7877, -2.9832),13)
//    map.addControl(new GLargeMapControl());
//    map.addControl(new GMapTypeControl());
    var dirn = new GDirections();

//      var firstpoint = true;
    var gmarkers = [];
    var gpolys = [];
    var dist = 0;

// == When the user clicks on a the map, get directiobns from that point to itself ==

gmarkers.push(new google.maps.LatLng(53.7877, -2.9832));
gmarkers.push(new google.maps.LatLng(53.9007, -2.9832));
gmarkers.push(new GLatLng(53.600, -2.700));



for (var i = 0; i < gmarkers.length-1; i++) {
    console.log(gmarkers[i]);
                dirn.loadFromWaypoints([gmarkers[i].toUrlValue(6),gmarkers[i+1].toUrlValue(6)],{getPolyline:true});

}


// == when the load event completes, plot the point on the street ==
    GEvent.addListener(dirn,"load", function() {
// snap to last vertex in the polyline
        var n = dirn.getPolyline().getVertexCount();
            map.addOverlay(dirn.getPolyline());
            gpolys.push(dirn.getPolyline());
            dist += dirn.getPolyline().getDistance();
            document.getElementById("distance").innerHTML="Path length: "+(dist/1000).toFixed(2)+" km. "+(dist/1609.344).toFixed(2)+" miles.";
           });
    GEvent.addListener(dirn,"error", function() {
        GLog.write("Failed: "+dirn.getStatus().code);
    });
console.log(dirn);

在 google api V3 中，这种简单的方式行不通。有类似路线服务的东西，但我不知道如何通过我的点绘制折线，折线将被捕捉到道路。