如何通过 GoogleMaps 上的多个点绘制从 A 到 B 的路线？

Question

Imagine I want to go from A to B through 3 waypoints. I have this code, which forms the Google Maps direction URL:

fun getMapsApiDirectionsUrl(): String {
    val origin = "origin=" + currentLocation.latitude + "," + currentLocation.longitude;
    val waypoints = "waypoints=optimize:true|" + loc1.latitude + "," + loc1.longitude + "|" + loc2.latitude + "," + loc2.longitude + "|" + loc3.latitude + "," + loc3.longitude
    val destination = "destination=" + loc4.latitude + "," + loc4.longitude
    val sensor = "sensor=false"
    val key = "key="+API_KEY;
    val params = "$origin&$waypoints&$destination&$sensor&$key"
    val output = "json"

    val url = "https://maps.googleapis.com/maps/api/directions/" + output + "?" + params
    System.out.println("map url: "+url)
    return url
}

Opening the URL on browser gave this:

{ "routes" : [], "status" : "ZERO_RESULTS" }

But if I only use 1 waypoint (instead of 3 like shown above), the direction will be displayed in 1 big JSON correctly, like this:

{ "geocoded_waypoints" : [ { "geocoder_status" : "OK", "place_id" : "ChIJH87yjIXxaS4R5_ww8ZCufeo", "types" : [ "clothing_store", "establishment", "point_of_interest", "store" ] }, { "geocoder_status" : "OK", "place_id" : "ChIJ1wVXzIDxaS4RkyUYgf3ZV0c", "types" : [ "street_address" ] }, { "geocoder_status" : "OK", "place_id" : "ChIJrfOSGBXxaS4Ro595K_5ClCg", "types" : [ "establishment", "hospital", "point_of_interest" ] } ], "routes" : [ { "bounds" : { "northeast" : { "lat" : -6.2399232, "lng" : 106.8161445 }, "southwest" : { "lat" : -6.2684858, "lng" : 106.7929824 } }, "copyrights" : "Map data ©2019 Google", "legs" : [ { "distance" : { "text" : "1.2 km", "value" : 1205 }, "duration" : { "text" : "4 mins", "value" : 254 }, "end_address" : "Jl. Kemang Raya No.54, RT.8/RW.2, Bangka, Kec. Mampang Prpt., Kota Jakarta Selatan, Daerah Khusus Ibukota Jakarta 12730, Indonesia", "end_location" : { "lat" : -6.263443499999999, "lng" : 106.8160131....

So does it mean I can only use 1 waypoint?

Answer 1

There is no way from origin to destination via waypoints set. The second URL:

https://maps.googleapis.com/maps/api/directions/json?origin=-6.2684059,106.8103103&waypoints=optimize:true%7C-6.263459,106.815903%7C-6.240607,106.792831%7C-6.240607,106.792831&destination=-6.235759,6.823277&sensor=false&key=<YOUR_KEY>

contains unreachable destination destination=-6.235759,6.823277 in Atlantic Ocean. Probably destination should be 106.823277 instead of 6.823277 : destination=-6.235759,106.823277 if all the positions should refer to valid locations in Jakarta. So, double check code, that compose URL for Directions API request.