Openlayers 3 特征集合中每个特征的不同颜色

我用openlayers 3在地图中上传了一个geojson文件。geojson文件是一个FeatureCollection，具有LineString类型的5个功能。 如何为每个功能添加不同的颜色以区分路径？ 如果我将颜色添加到geojson文件的样式中，则不会读取该文件，如果我将颜色添加到笔划中，则所有功能都以单一颜色着色

下面我添加代码

谢谢

var vector = new ol.layer.Vector({
            source: new ol.source.Vector({
                format: new ol.format.GeoJSON(),
                url: 'http://localhost/joggo_wp/percorsi.geojson'
            }),
            style: new ol.style.Style({
                stroke: new ol.style.Stroke({
                    color: "#ff000",
                    width: 2.5,                     
                })
            }),     
        });

文件GEOJSON:

{

“类型”：“FeatureCollection”， “crs”：{“类型”：“名称”，“属性”：{“名称”：“urn:ogc:def:crs:EPSG:：4326”}， “特点”：[ {“类型”：“特征”，“属性”：{“ID”：1.0，“LUNGH_M”：1970.0，“NOME”：“Percorso 1”，“PARTENZA”：“Via del Poggio Imperiale 4”，“ARRIVO”：“Via di S.Leonardo 59n”，“LUNGHEZZA”：“1,97 km”}，“风格”：{“颜色”：“ff0000”}，“几何体”：{“类型”：“线条”，“坐标”：[11.2420370004032,43.7599754752376]，[ 11.247204649917521, 43.750208064502473 ], [ 11.247446659153409, 43.750240561464494 ], [ 11.247746238597509, 43.750179530458503 ], [ 11.247960306028226, 43.750118937742307 ], [ 11.248108264989046, 43.749966781403657 ], [ 11.248240378523741, 43.749814084940027 ], [ 11.248897533371567, 43.75006527742493 ], [ 11.249140299088037, 43.750277668555015 ], [ 11.250198620263028, 43.751078552926899 ], [ 11.250259518649738, 43.751623211022611 ], [ 11.250562891152564, 43.751940055106814 ], [ 11.250844806161599, 43.752116454510677 ], [ 11.250976903611187, 43.752184285854881 ], [ 11.251025276742347, 43.752394633135999 ], [ 11.251095944135562, 43.752551715399683 ], [ 11.252075754111447, 43.753064192693351 ], [ 11.252260569522404, 43.753162663730734 ], [ 11.252298216347477, 43.753302788154329 ], [ 11.252042422884459, 43.753607171300693 ], [ 11.252089750740879, 43.754005360713535 ], [ 11.252046702595303, 43.754152945071198 ], [ 11.251940462780629, 43.754342861090443 ], [ 11.251887408111035, 43.754762904036816 ] ] } },

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您需要创建一个样式函数来处理此类情况

因此，让你的风格发挥作用：

 var styleFunction = function(feature) {
       console.log(feature);
     //now you can use any property of your feature to identify the different colors
     //I am using the ID property of your data just to demonstrate
      var color;
      if (feature.get("ID")==1){
      color = "red";
      } else if (feature.get("ID")==2){
      color = "green";
      } else {
     color = "black"; 
      }

      var retStyle =   new ol.style.Style({
          stroke: new ol.style.Stroke({ 
            color: color,
            width: 5
          })
        });
       return retStyle;

      };

然后将此函数指定给向量层的样式

var vector = new ol.layer.Vector({
            source: new ol.source.Vector({
                format: new ol.format.GeoJSON(),
                url: 'http://localhost/joggo_wp/percorsi.geojson'
            }),
            style: styleFunction     
        });

这是一个