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说说geotools中坐标转换那点事

2017-07-05 08:45 706 查看
概述：

本文说说geotools中坐标转换的那点事情，以WGS84和web墨卡托相互转换为例。

效果：
转换前
转换后
单个Geometry转换

实现代码：
package com.lzugis.geotools;

import java.io.File;
import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;

import org.geotools.data.FeatureWriter;
import org.geotools.data.FileDataStoreFactorySpi;
import org.geotools.data.Transaction;
import org.geotools.data.shapefile.ShapefileDataStore;
import org.geotools.data.shapefile.ShapefileDataStoreFactory;
import org.geotools.data.simple.SimpleFeatureIterator;
import org.geotools.data.simple.SimpleFeatureSource;
import org.geotools.feature.simple.SimpleFeatureTypeBuilder;
import org.geotools.geometry.jts.JTS;
import org.geotools.geometry.jts.JTSFactoryFinder;
import org.geotools.referencing.CRS;
import org.geotools.referencing.crs.DefaultGeographicCRS;
import org.opengis.feature.simple.SimpleFeature;
import org.opengis.feature.simple.SimpleFeatureType;
import org.opengis.referencing.crs.CoordinateReferenceSystem;
import org.opengis.referencing.operation.MathTransform;

import com.vividsolutions.jts.geom.Geometry;
import com.vividsolutions.jts.geom.GeometryFactory;
import com.vividsolutions.jts.io.WKTReader;
import com.vividsolutions.jts.io.WKTWriter;

public class ProjectTrans {
private static GeometryFactory geometryFactory = JTSFactoryFinder.getGeometryFactory( null );
private static WKTReader reader = new WKTReader( geometryFactory );
private static WKTWriter write = new WKTWriter();
static ProjectTrans proj = new ProjectTrans();

final String strWKTMercator = "PROJCS[\"World_Mercator\","
+ "GEOGCS[\"GCS_WGS_1984\","
+ "DATUM[\"WGS_1984\","
+ "SPHEROID[\"WGS_1984\",6378137,298.257223563]],"
+ "PRIMEM[\"Greenwich\",0],"
+ "UNIT[\"Degree\",0.017453292519943295]],"
+ "PROJECTION[\"Mercator_1SP\"],"
+ "PARAMETER[\"False_Easting\",0],"
+ "PARAMETER[\"False_Northing\",0],"
+ "PARAMETER[\"Central_Meridian\",0],"
+ "PARAMETER[\"latitude_of_origin\",0],"
+ "UNIT[\"Meter\",1]]";
/**
* 经纬度转WEB墨卡托
* @param geom
* @return
*/
public Geometry lonlat2WebMactor(Geometry geom){
try{
//这里是以OGC WKT形式定义的是World Mercator投影，网页地图一般使用该投影

//			CoordinateReferenceSystem crsTarget = CRS.parseWKT(strWKTMercator);
CoordinateReferenceSystem crsTarget = CRS.decode("EPSG:3857");

// 投影转换
MathTransform transform = CRS.findMathTransform(DefaultGeographicCRS.WGS84, crsTarget);
return JTS.transform(geom, transform);
}
catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
return null;
}
}

public void projectShape(String inputShp, String outputShp){
try {
//源shape文件
ShapefileDataStore shapeDS = (ShapefileDataStore) new ShapefileDataStoreFactory().createDataStore(new File(inputShp).toURI().toURL());
//创建目标shape文件对象
Map<String, Serializable> params = new HashMap<String, Serializable>();
FileDataStoreFactorySpi factory = new ShapefileDataStoreFactory();
params.put(ShapefileDataStoreFactory.URLP.key, new File(outputShp).toURI().toURL());
ShapefileDataStore ds = (ShapefileDataStore) factory.createNewDataStore(params);
// 设置属性
SimpleFeatureSource fs = shapeDS.getFeatureSource(shapeDS.getTypeNames()[0]);
//下面这行还有其他写法，根据源shape文件的simpleFeatureType可以不用retype，而直接用fs.getSchema设置
CoordinateReferenceSystem crs = CRS.parseWKT(strWKTMercator);
ds.createSchema(SimpleFeatureTypeBuilder.retype(fs.getSchema(), crs));

//设置writer
FeatureWriter<SimpleFeatureType, SimpleFeature> writer = ds.getFeatureWriter(ds.getTypeNames()[0], Transaction.AUTO_COMMIT);

//写记录
SimpleFeatureIterator it = fs.getFeatures().features();
try {
while (it.hasNext()) {
SimpleFeature f = it.next();
SimpleFeature fNew = writer.next();
fNew.setAttributes(f.getAttributes());
Geometry geom = proj.lonlat2WebMactor((Geometry)f.getAttribute("the_geom"));
fNew.setAttribute("the_geom", geom);
}
}
finally {
it.close();
}
writer.write();
writer.close();
ds.dispose();
shapeDS.dispose();
}
catch (Exception e) {
e.printStackTrace();
}
}

/**
* 工具类测试方法
* @param args
*/
public static void main(String[] args){
String wktPoint = "POINT(100.02715479879 33.462715497945)";
String wktLine = "LINESTRING(108.32803893589 41.306670233001,99.950999898452 25.84722546391)";
String wktPolygon = "POLYGON((100.02715479879 32.168082192159,102.76873121104 37.194305614622,107.0334056301 34.909658604412,105.96723702534 30.949603786713,100.02715479879 32.168082192159))";
try {
long start = System.currentTimeMillis();

Geometry geom1 = (Geometry) reader.read(wktPoint);
Geometry geom1T = proj.lonlat2WebMactor(geom1);

Geometry geom2 = (Geometry) reader.read(wktLine);
Geometry geom2T = proj.lonlat2WebMactor(geom2);

Geometry geom3 = (Geometry) reader.read(wktPolygon);
Geometry geom3T = proj.lonlat2WebMactor(geom3);

System.out.println(write.write(geom1T));
System.out.println(write.write(geom2T));
System.out.println(write.write(geom3T));
String inputShp = "D:\\data\\beijing\\China4326.shp",
outputShp = "D:\\data\\beijing\\China3857.shp";
proj.projectShape(inputShp, outputShp);
System.out.println("坐标转换完成，共耗时"+(System.currentTimeMillis() - start)+"ms");
}
catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}