我是GeoJSON的新手,即时通讯目前遇到一个我不知道该怎么做的问题。
这是我的FeatureCollection的摘要
FeatureCollection fc = new FeatureCollection();
Map<String, Object> properties = new HashMap<String, Object>();
for(int i = 0; i < platforms.size(); i ++) {
Feature feature = new Feature();
Point geometry = new Point();
Dto dto = platforms.get(i);
Position position = new Position(dto.getLat(), dto.getLon());
fc.addFeature(feature);
geometry.setCoordinates(position);
feature.setGeometry(geometry);
feature.setProperties(properties);
properties.put("name", dto.getName());
properties.put("msl", dto.getMsl());
properties.put("id", dto.getId());
}
return fc.toString();
我希望我的输出看起来像这样:
{
"type":"FeatureCollection"
features":[
{
"type":"Feature"
"geometry": {
"type":"Point"
"coordinates":[
-120.200000,
10.100000
]
},
"properties": {
"name": "1"
"height": "100.00"
"id": "null"
}
}
{
"type":"Feature"
"geometry": {
"type":"Point"
"coordinates\":[
-130.200000,
20.100000
] \n "
}, \n "
"properties": { "
"name": "2"
"height": "100.00"
"id": "null"
}
}
]
}
据我所知,通过调试,正确的信息已放入功能中,但是每当我返回featureCollection时,我都会得到以下信息:
mil.nga.sf.geojson.FeatureCollection@366ac49b
我对geojson不太了解,但似乎我错误地返回了FeatureCollection并打印出其名称或其他名称。
简而言之,如何打印FeatureCollection的内容?
编辑:这是实现gson后得到的输出。
{
"features": [
{
"feature": {
"geometry": {
"x": 10.1,
"y": -120.2,
"z": null,
"m": null,
"geometryType": "POINT",
"hasZ": false,
"hasM": false
},
"properties": {
"msl": 100.0,
"name": "1",
"id": null
}
},
"id": null,
"bbox": null,
"foreignMembers": {}
},
{
"feature": {
"geometry": {
"x": 20.1,
"y": -130.2,
"z": null,
"m": null,
"geometryType": "POINT",
"hasZ": false,
"hasM": false
},
"properties": {
"msl": 100.0,
"name": "2",
"id": null
}
},
"id": null,
"bbox": null,
"foreignMembers": {}
}
],
"bbox": null,
"foreignMembers": {}
我不确定该怎么做才能使它反映我想要的输出。
您的问题是您正在调用fc.toString();
,这将达到默认的Object.toString()方法。这将转储一些类名+地址/ id的String,具体取决于所使用的JVM。
与其调用toString(),不如使用google gson之类的JSON库,并在代码底部添加几行:
final GsonBuilder gb = new GsonBuilder();
gb.setPrettyPrinting();
gb.serializeNulls();
// gb.excludeFieldsWithoutExposeAnnotation(); // maybe use for more control
final Gson gson = gb.create();
final String jsonText = gson.toJson(fc);
return jsonText;
还可以考虑编写一个实用程序类,使用您选择的默认设置为您执行此操作:
public class MyJsonUtil {
static public String toJSON(final Object pObject) {
final GsonBuilder gb = new GsonBuilder();
gb.setPrettyPrinting();
gb.serializeNulls();
// gb.excludeFieldsWithoutExposeAnnotation(); // maybe use for more control
final Gson gson = gb.create();
final String jsonText = gson.toJson(pObject);
return jsonText;
}
}
然后在代码末尾,您只需调用return MyJsonUtil.toJSON(fc)
。
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