How to get polyline from Google Maps Directions Api

问题

I'm trying to draw a polyline using the Google Maps Directions Api, but how do I use the JSON values to make this, because in the api, there is a lot of lat and long and polylines.points like this:

cxwnFtdct@JEVGLCR?PDTFNHTNNNPJPDRDN?JCHCv@i@VQTK`CkF

and I don't know which one should I use, can anyone help me :)

{
  geocoded_waypoints: [
    {},
    {}
  ],
  routes: [
    {
      bounds: {
        northeast: {
          lat: 39.2846595,
          lng: -8.7036795
        },
        southwest: {
          lat: 38.7223249,
          lng: -9.1393372
        }
      },
      copyrights: "Dados do mapa ©2017 Google, Inst. Geogr. Nacional",
      legs: [
        {
          distance: {},
          duration: {},
          end_address: "Lisboa, Portugal",
          end_location: {
            lat: 38.7223249,
            lng: -9.1393372
          },
          start_address: "Santarém, Portugal",
          start_location: {
            lat: 39.2846595,
            lng: -8.7049071
          },
          steps: [
            {
              distance: {},
              duration: {},
              end_location: {
                lat: 39.2822117,
                lng: -8.7036403
              },
              html_instructions: "Siga <b>sul</b> em direção a <b>N3</b>",
              polyline: {
                points: "cxwnFtdct@JEVGLCR?PDTFNHTNNNPJPDRDN?JCHCv@i@VQTK`CkF"
              },
              start_location: {
                lat: 39.2846595,
                lng: -8.7049071
              },
              travel_mode: "DRIVING"
            },
            {},
          ],
          traffic_speed_entry: [],
          via_waypoint: []
        }
      ],
      overview_polyline: {   points:"cxwnFtdct@dAQlAf@fAf@|Aq@l@]pCcFhCjA|LfJlAT~@IpDi@jAb@f@HXi@t@kBhBeBx@Qz@z@dClHzFpW`H|RvTpj@`AxAdBdAnAXhB?fBk@rAcAnG_HhCgAjAKrATbA`Al@lBHnAc@rFgBhIkCxMBfIlBvHnBtCnB|AnEdCrJxFj@fB@h@OhAgCtHGfCl@jAlA\jE]tDBzBb@tLxFtK~E`d@hShIzEtDhDxDrEfDpFlFjNvDtRdDjThF`TzH`QhEhG|EvFhL`JpJtE|LpEdOpFjOzGlPfJlHzE~NjLfQvPfP|RtHrKxDjGfI|NdHbOvGjPfCbHpCtIvJh_@vG|[|CtNvFvSvE~MfI|QzLbTfNxQbKlKrRzP|NnNvNlQjIzMnLfV`T|h@nDbHhIdMxFjH~JrMnEfHzIrQfHvOtEjI|MnQfNzP`FzI~EnLrKp[nDlHvErHzL~MbRbM`EjCjFxEtRnX|D~EjIhI~WrRxGlGdFnG`JjNxHzKfTxVfKfRfMbRlErHtBlFxIjYvHnPpBtFxF~WpCjHjGhJfDzClF~CnDlArDl@pC\vHXvX[lOaB|GcBdFqBxQwJbDmAxE_ApJ_@jEXtItBrQ~EbQbDlUfBpMfA|IxCbF`DhGlGnJjKtJrF`SpFbRnDdUxAbGrAlEjBnFpDtNnMfGlE~[lTbRdQjTpUxH`GjHfEnGlC`O|DrUxEnEzAfFrBnSpIjPnDxSlAf\lAl~@hDzRrAjOpBvKrBrQtEv^pM``@rPrR|JxSdMlGnGfGtH~HxFdFlBtGfApGp@bG|AnHxD|FzFrH`L~FvH|HrFrFtBtFjA~Mt@pHR|FhA`IfDpEbDzFxGrHrKhEtErF`EnS`MzMvItSdUfF~DtE~B|SrInEnBzDtCxN`QpQfVtQ~Yjn@~fAnK`RvLlRzEjF|GlFrc@vUfRjKfIvGxDhEjIxKdN~T`L~MrFvE~LhIlp@fb@xCtBzFtFbEzFbDrGhH`TfF|JnGfHzEdD|UdIpTdHtKtFj]nUrEzC~[pTfLfG|EbB~KfCnTvDpmAxSzs@~LhOfDzOdFfOxGdY`O`k@zYnVzMlK|HrFjFbXj[rCbCvDfB|FfBbD^xRBlb@nBrIdArJvDfD|B|FzFvFzHnCbIDrCk@dA_A_@q@mHz@sAvAJ^f@r@n@x@UR_@fBGjET`S~@ro@pCpXpAfFp@dEhCnGtE@HXl@n@H^W|ASpShAbZxAtPp@~SjAzGZKdDStBd@x@dC@nEVz@HtAp@b@\OZ|AbBxDnFJf@"
      },
      summary: "A1",
      warnings: [],
      waypoint_order: []
    }
  ],
  status: "OK"
}

回答1:

Convert overview_polyline into list of LatLng and add as polyling in map

Use PolyUtil provided from google.

https://github.com/googlemaps/android-maps-utils/blob/master/demo/src/com/google/maps/android/utils/demo/PolyDecodeDemoActivity.java

https://github.com/googlemaps/android-maps-utils/blob/master/library/src/com/google/maps/android/PolyUtil.java

回答2:

Check Google Maps Android API Utility Library has some predefined method for parsing polyline and many more.

回答3:

I have put my answer to some post which contains your answer as well. You can find Parser class and Aysc class as well to draw polyline from response on the map.

Here is the link for post How to buffer a polyline in Android or draw a polygon around a polyline?

来源：https://stackoverflow.com/questions/43068378/how-to-get-polyline-from-google-maps-directions-api