我在数据库中有2个点的经度和纬度，我希望我的Google Map显示从A点到B点的路线。
就像我们在这里看到的一样（Google Maps Directions）
如何在地图上绘制该方向线？
Answers:
我创建了一个有效的演示，演示了如何通过Java脚本在Javascript中使用Google Maps API Directions服务
DirectionsService 对象发送和接收指示请求DirectionsRenderer 在地图上呈现返回路线的对象function initMap() {
var pointA = new google.maps.LatLng(51.7519, -1.2578),
pointB = new google.maps.LatLng(50.8429, -0.1313),
myOptions = {
zoom: 7,
center: pointA
},
map = new google.maps.Map(document.getElementById('map-canvas'), myOptions),
// Instantiate a directions service.
directionsService = new google.maps.DirectionsService,
directionsDisplay = new google.maps.DirectionsRenderer({
map: map
}),
markerA = new google.maps.Marker({
position: pointA,
title: "point A",
label: "A",
map: map
}),
markerB = new google.maps.Marker({
position: pointB,
title: "point B",
label: "B",
map: map
});
// get route from A to B
calculateAndDisplayRoute(directionsService, directionsDisplay, pointA, pointB);
}
function calculateAndDisplayRoute(directionsService, directionsDisplay, pointA, pointB) {
directionsService.route({
origin: pointA,
destination: pointB,
travelMode: google.maps.TravelMode.DRIVING
}, function(response, status) {
if (status == google.maps.DirectionsStatus.OK) {
directionsDisplay.setDirections(response);
} else {
window.alert('Directions request failed due to ' + status);
}
});
}
initMap(); html,
body {
height: 100%;
margin: 0;
padding: 0;
}
#map-canvas {
height: 100%;
width: 100%;
}<script src="https://maps.googleapis.com/maps/api/js?sensor=false"></script>
<div id="map-canvas"></div>同样在Jsfiddle上：http : //jsfiddle.net/user2314737/u9no8te4/
您可以通过发出如下请求的API_KEY使用Web服务：
https://maps.googleapis.com/maps/api/directions/json?origin=Toronto&destination=Montreal&key=API_KEY
可以在Google Developer Console中获取API_KEY，每天可以免费使用2500个配额。
请求可以返回可用于在地图上绘制路径的JSON或XML结果。
使用Google Maps Directions API的Web服务的官方文档在这里
在您的情况下，这是使用路线服务的实现。
function displayRoute() {
var start = new google.maps.LatLng(28.694004, 77.110291);
var end = new google.maps.LatLng(28.72082, 77.107241);
var directionsDisplay = new google.maps.DirectionsRenderer();// also, constructor can get "DirectionsRendererOptions" object
directionsDisplay.setMap(map); // map should be already initialized.
var request = {
origin : start,
destination : end,
travelMode : google.maps.TravelMode.DRIVING
};
var directionsService = new google.maps.DirectionsService();
directionsService.route(request, function(response, status) {
if (status == google.maps.DirectionsStatus.OK) {
directionsDisplay.setDirections(response);
}
});
}
// First Initiate your map. Tie it to some ID in the HTML eg. 'MyMapID'
var map = new google.maps.Map(
document.getElementById('MyMapID'),
{
center: {
lat: Some.latitude,
lng: Some.longitude
}
}
);
// Create a new directionsService object.
var directionsService = new google.maps.DirectionsService;
directionsService.route({
origin: origin.latitude +','+ origin.longitude,
destination: destination.latitude +','+ destination.longitude,
travelMode: 'DRIVING',
}, function(response, status) {
if (status === google.maps.DirectionsStatus.OK) {
var directionsDisplay = new google.maps.DirectionsRenderer({
suppressMarkers: true,
map: map,
directions: response,
draggable: false,
suppressPolylines: true,
// IF YOU SET `suppressPolylines` TO FALSE, THE LINE WILL BE
// AUTOMATICALLY DRAWN FOR YOU.
});
// IF YOU WISH TO APPLY USER ACTIONS TO YOUR LINE YOU NEED TO CREATE A
// `polyLine` OBJECT BY LOOPING THROUGH THE RESPONSE ROUTES AND CREATING A
// LIST
pathPoints = response.routes[0].overview_path.map(function (location) {
return {lat: location.lat(), lng: location.lng()};
});
var assumedPath = new google.maps.Polyline({
path: pathPoints, //APPLY LIST TO PATH
geodesic: true,
strokeColor: '#708090',
strokeOpacity: 0.7,
strokeWeight: 2.5
});
assumedPath.setMap(map); // Set the path object to the map