Using Waypoints in Routes

As noted within the  DirectionsRequest, you may also specify waypoints (of type DirectionsWaypoint) when calculating routes using the Directions service. Waypoints allow you to calculate routes through additional locations, in which case the returned route passes through the given waypoints.

A waypoint consists of the following fields:


	
location (required) specifies the address   of the waypoint.
	
stopover (optional) indicates whether this   waypoint is a actual stop on the route (true)   or instead only a preference to route through the indicated   location (false). Stopovers are true by default.


By default, the Directions service calculates a route through the provided waypoints in their given order. Optionally, you may pass optimizeWaypoints: true within the  DirectionsRequest to allow the Directions service to optimize the provided route by rearranging the waypoints in a more efficient order. (This optimization is an application of the  Travelling Salesman Problem.) All waypoints must be stopovers for the Directions service to optimize their route.

If you instruct the Directions service to optimize the order of its waypoints, their order will be returned in the optimized_waypoints_order field within the DirectionsResult object.

The following example calculates cross-country routes across the United States using a variety of start points, end points, and waypoints. (To select multiple waypoints, press Ctrl-Click when selecting items within the list.) Note that we inspect the routes.start_geocode.formatted_address and routes.end_geocode.formatted_address to provide us with the text for each route's start and end point.


var directionDisplay;
var directionsService = new google.maps.DirectionsService();
var map;

function initialize() {
  directionsDisplay = new google.maps.DirectionsRenderer();
  var chicago = new google.maps.LatLng(41.850033, -87.6500523);
  var myOptions = {
    zoom: 6,
    mapTypeId: google.maps.MapTypeId.ROADMAP,
    center: chicago
  }
  map = new google.maps.Map(document.getElementById("map_canvas"), myOptions);
  directionsDisplay.setMap(map);
}
  
function calcRoute() {
  var start = document.getElementById("start").value;
  var end = document.getElementById("end").value;
  var waypts = [];
  var checkboxArray = document.getElementById("waypoints");
  for (var i = 0; i < checkboxArray.length; i++) {
    if (checkboxArray.options[i].selected == true) {
      waypts.push({
          location:checkboxArray[i].value,
          stopover:true
      });
    }
  }

  var request = {
      origin: start, 
      destination: end,
      waypoints: waypts,
      optimizeWaypoints: true,
      travelMode: google.maps.DirectionsTravelMode.DRIVING
  };
  directionsService.route(request, function(response, status) {
    if (status == google.maps.DirectionsStatus.OK) {
      directionsDisplay.setDirections(response);
      var route = response.routes[0];
      var summaryPanel = document.getElementById("directions_panel");
      summaryPanel.innerHTML = "";
      // For each route, display summary information.
      for (var i = 0; i < route.legs.length; i++) {
        var routeSegment = i+1;
        summaryPanel.innerHTML += "<b>Route Segment: " + routeSegment + "</b><br />";
        summaryPanel.innerHTML += route.legs[i].start_geocode.formatted_address + " to ";
        summaryPanel.innerHTML += route.legs[i].end_geocode.formatted_address + "<br />";
        summaryPanel.innerHTML += route.legs[i].distance.text + "<br /><br />";
      }
    }
  });
}

http://code.google.com/intl/zh-CN/apis/maps/documentation/javascript/services.html#Geocoding

http://code.google.com/intl/zh-CN/apis/maps/documentation/javascript/examples/directions-waypoints.html