正文
Arcgis for Android 空间数据WKT与JSON描述
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点线面数据标准格式
一、 点
WKT:
POINT(-118.4 -45.2)
JSON:
{
"x": -118.4,
"y": -45.2,
"spatialReference": {
"wkid": 4326
}
}
二、 多点
WKT:
MULTIPOINT(1.01 2.02, 2.01 3.01)
注意：这个结构与OGC标准不同，这是sqlite的几何体的结构。
OGC标准： MULTIPOINT( (1.01 2.02), (2.01 3.01))
JSON:
{
"points": [
[
1.01,
2.02
],
[
2.01,
3.01
]
],
"spatialReference": {
"wkid": 4326
}
}
三、 线
WKT:
LINESTRING(668540.706869 4858267.857562, 668545.871539 4858270.322537, 668535.504206 4858270.059492)
JSON:
{
"paths": [
[
[
668540.706869,
4858267.857562
],
[
668545.871539,
4858270.322537
],
[
668535.504206,
4858270.059492
]
]
],
"spatialReference": {
"wkid": 102100
}
}
四、 多义线
WKT:
MULTILINESTRING((668540.706869 4858267.857562,668545.871539 4858270.322537),(668535.504206 4858270.059492, 668535.504206 4858270.059492))
JSON:
{
"rings": [
[
[
668540.706869,
4858267.857562
],
[
668545.871539,
4858270.322537
]
],
[
[
668535.504206,
4858270.059492
],
[
668535.504206,
4858270.059492
]
]
],
"spatialReference": {
"wkid": 102100
}
}
五、 多边形
注意： 多边形首尾两点坐标是相同的。
WKT:
POLYGON((10172081.707086032 3426616.2980572497,10181098.35305895 3439876.071546833,10188842.060776865 3423858.265171416,10172081.707086032 3426616.2980572497))
JSON:
{
"rings": [
[
[
10172081.707086032,
3426616.2980572497
],
[
10181098.35305895,
3439876.071546833
],
[
1266114.9310351424,
3430468.042044999
],
[
10188842.060776865,
3423858.265171416
] ,
[
10172081.707086032,
3426616.2980572497
]
]
],
"spatialReference": {
"wkid": 102100
}
}
六、 多多边形
WKT:
MULTIPOLYGON(((752912.250297 5028764.989051, 753066.871935 5028928.677375, 753417.249537 5028775.949135, 753828.826422 5027429.54477, 752992.3308 5028072.927877, 752912.250297 5028764.989051)))
JSON:
{
"rings": [
[
[
752912.250297,
5028764.989051
],
[
753066.871935,
5028928.677375
],
[
753417.249537,
5028775.949135
],
[
753828.826422,
5027429.54477
],
[
752992.3308,
5028072.927877
],
[
752912.250297,
5028764.989051
]
]
],
"spatialReference": {
"wkid": 102100
}
}
实际应用开发
1) WKT与JSON格式的相互转换。
WKT转成JSON方法: String WKT.read(String wktsr)
JSON转成WKT方法: String WKT.write(String jsonstr)
2) 基于第一点可将WKT生成Arcgis for Android 的几何体Geometry。
从Spatialite数据库读取几何体的WKT字符串：
SELECT ASTEXT(geometry) FROM test
将WKT字符串转成JSON，通过GeometryEngine的jsonToGeometry方法将JSON转成Geometry对象。
String str= "{\"rings\":[[[1007664.4779535953,3710553.4649297176],[957962.4793888753,3190110.978805308],[1266114.9310351424,3430468.042044999],[1007664.4779535953,3710553.4649297176]]],\"spatialReference\":{\"wkid\":102100}} ";
JsonFactory jsonFactory = new JsonFactory();
try {
JsonParser jsonParser = jsonFactory.createJsonParser(str);
MapGeometry mapgeo = GeometryEngine.jsonToGeometry(jsonParser);
Geometry geo = mapgeo.getGeometry();
} catch (JsonParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
3) 将Arcgis for android Geomtery 存入空间数据库Spatialite中，我是指存入空间数据而不是WKT字符串。
JSON字符串是通过GeometryEngine的geometryToJson方法生成，转成WKT后再插入空间数据库。
将多点数据插入Spatialite数据库：
INSERT INTO test ( geometry) VALUES(GeomFromText('MULTIPOINT(1.01 2.02, 2.01 3.01)', 4326))
