目錄
一、引言
數據庫中經常存儲的格式是符合OGC標準的WKT或WKB，而在網絡中經常傳輸的格式是json，因此我們會經常把各種數據轉爲geojson的形式以服務形式發出，供客戶端使用。當然你硬要用wkt格式也行，沒人管你，自己知道就ok，由於涉及到屬性數據只是建議geojson比較方便，畢竟WFS也是用的geojson返回的==
二、代碼操作
1、服務端
讀取shp數據，解析出simplefeature，使用featurejson轉化爲json，然後拼接輸出。
/**
* 後臺將shp數據轉爲geojson，返回
* @return
*/
@RequestMapping("/geojson")
@ResponseBody
public Object shp2geojson()
{
String shpPath=this.getClass().getResource("/").getFile()+"/file/pointgbk.shp";
String jsonPath=this.getClass().getResource("/").getFile()+"file/point.geojson";
Map map = new HashMap();
//新建json對象
FeatureJSON fjson = new FeatureJSON();
JSONObject geojsonObject=new JSONObject();
geojsonObject.put("type","FeatureCollection");
try{
//獲取featurecollection
File file = new File(shpPath);
ShapefileDataStore shpDataStore = null;
shpDataStore = new ShapefileDataStore(file.toURL());
//設置編碼
/* Charset charset = Charset.forName("GBK");
shpDataStore.setCharset(charset);*/
String typeName = shpDataStore.getTypeNames()[0];
SimpleFeatureSource featureSource = null;
featureSource = shpDataStore.getFeatureSource (typeName);
SimpleFeatureCollection result = featureSource.getFeatures();
SimpleFeatureIterator itertor = result.features();
JSONArray array = new JSONArray();
//遍歷feature轉爲json對象
while (itertor.hasNext())
{
SimpleFeature feature = itertor.next();
StringWriter writer = new StringWriter();
fjson.writeFeature(feature, writer);
String temp=writer.toString();
byte[] b=temp.getBytes("iso8859-1");
temp=new String(b,"gbk");
System.out.println(temp);
JSONObject json = JSON.parseObject(temp);
array.add(json);
}
geojsonObject.put("features",array);
itertor.close();
long startTime=System.currentTimeMillis();
//將json字符串使用字符流寫入文件
/* File outputfile=new File(jsonPath);
BufferedWriter bufferedWriter=new BufferedWriter(new FileWriter(outputfile));
bufferedWriter.write(JSON.toJSONString(geojsonObject));
bufferedWriter.flush();
bufferedWriter.close();*/
File outputfile=new File(jsonPath);
FileOutputStream fileOutputStream=new FileOutputStream(outputfile);
OutputStreamWriter outputStreamWriter=new OutputStreamWriter(fileOutputStream,"utf-8");
outputStreamWriter.write(JSON.toJSONString(geojsonObject));
outputStreamWriter.flush();
outputStreamWriter.close();
//將json字符串使用字節流寫入文件
/* File outputfile=new File(jsonPath);
BufferedOutputStream bufferedOutputStream=new BufferedOutputStream(new FileOutputStream(outputfile));
byte[] bytes= JSON.toJSONString(geojsonObject).getBytes("utf-8");
bufferedOutputStream.write(bytes);
//fileOutputStream.write(JSON.toJSONString(geojsonObject));
bufferedOutputStream.flush();
bufferedOutputStream.close();*/
long endTime=System.currentTimeMillis();
System.out.println("當前程序耗時："+(endTime-startTime)+"ms");
}
catch(Exception e){
map.put("status", "failure");
map.put("message", e.getMessage());
e.printStackTrace();
}
return geojsonObject;
}
2、返回數據
{"features":[{"geometry":{"coordinates":[508909.854,299887.23],"type":"Point"},"id":"pointgbk.2","type":"Feature","properties":{"ExtendedEn":"{ 83103 } { L31-20201081-24 L31-20201081-24 }","SubClasses":"AcDbEntity:AcDbText:AcDbText","EntityHand":"1522","Text":"37.24","Linetype":"","Layer":"文字層組-標註"}},{"geometry":{"coordinates":[508884.9711,299895.6874],"type":"Point"},"id":"pointgbk.3","type":"Feature","properties":{"ExtendedEn":"{ 83103 } { L31-20201081-25 L31-20201081-25 }","SubClasses":"AcDbEntity:AcDbText:AcDbText","EntityHand":"1523","Text":"37.23","Linetype":"","Layer":"文字層組-標註"}},……],"type":"FeatureCollection"}
三、總結
- 使用wkt與geojson；
- 代碼操作將shp中的feature轉化爲geojson；
補充：
geojson轉shp
Map map = new HashMap();
GeometryJSON gjson = new GeometryJSON();
try{
String strJson = cm.getFileContent(jsonPath);
JSONObject json = new JSONObject(strJson);
JSONArray features = (JSONArray) json.get("features");
JSONObject feature0 = new JSONObject(features.get(0).toString());
System.out.println(feature0.toString());
String strType = ((JSONObject)feature0.get("geometry")).getString("type").toString();
Class<?> geoType = null;
switch(strType){
case "Point":
geoType = Point.class;
case "MultiPoint":
geoType = MultiPoint.class;
case "LineString":
geoType = LineString.class;
case "MultiLineString":
geoType = MultiLineString.class;
case "Polygon":
geoType = Polygon.class;
case "MultiPolygon":
geoType = MultiPolygon.class;
}
//創建shape文件對象
File file = new File(shpPath);
Map<String, Serializable> params = new HashMap<String, Serializable>();
params.put( ShapefileDataStoreFactory.URLP.key, file.toURI().toURL() );
ShapefileDataStore ds = (ShapefileDataStore) new ShapefileDataStoreFactory().createNewDataStore(params);
//定義圖形信息和屬性信息
SimpleFeatureTypeBuilder tb = new SimpleFeatureTypeBuilder();
tb.setCRS(DefaultGeographicCRS.WGS84);
tb.setName("shapefile");
tb.add("the_geom", geoType);
tb.add("POIID", Long.class);
ds.createSchema(tb.buildFeatureType());
//設置編碼
Charset charset = Charset.forName("GBK");
ds.setCharset(charset);
//設置Writer
FeatureWriter<SimpleFeatureType, SimpleFeature> writer = ds.getFeatureWriter(ds.getTypeNames()[0], Transaction.AUTO_COMMIT);
for(int i=0,len=features.length();i<len;i++){
String strFeature = features.get(i).toString();
Reader reader = new StringReader(strFeature);
SimpleFeature feature = writer.next();
feature.setAttribute("the_geom",gjson.readMultiPolygon(reader));
feature.setAttribute("POIID",i);
writer.write();
}
writer.close();
ds.dispose();