shapefile 文件获取坐标系

一、环境准备

装配GeoTools有两种方式，一种是配置maven工程的pom文件(配置方式参考官网)，另一种是下载geotools的jar包到本地导入依赖。

1. 下载jar的方式，下载路径：https://sourceforge.net/projects/geotools/files/

2. maven

      <dependency>
          <groupId>org.geotools</groupId>
          <artifactId>gt-epsg-extension</artifactId>
          <version>${geotools.version}</version>
        </dependency>
        <dependency>
            <groupId>org.geotools</groupId>
            <artifactId>gt-referencing</artifactId>
            <version>${geotools.version}</version>
        </dependency>    

 

 

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二、实现功能

从shape文件中读取坐标系信息。shape文件并不是一个文件而是一堆文件，坐标系信息存储在*.prj文件中。这是一个文本文件，可以用记事本打开。文件中存储的是WKT格式的坐标系信息。

PROJCS["WGS 84 / Pseudo-Mercator", 
  GEOGCS["WGS 84", 
    DATUM["World Geodetic System 1984", 
      SPHEROID["WGS 84", 6378137.0, 298.257223563, AUTHORITY["EPSG","7030"]], 
      AUTHORITY["EPSG","6326"]], 
    PRIMEM["Greenwich", 0.0, AUTHORITY["EPSG","8901"]], 
    UNIT["degree", 0.017453292519943295], 
    AXIS["Geodetic longitude", EAST], 
    AXIS["Geodetic latitude", NORTH], 
    AUTHORITY["EPSG","4326"]], 
  PROJECTION["Popular Visualisation Pseudo Mercator"], 
  PARAMETER["semi_minor", 6378137.0], 
  PARAMETER["latitude_of_origin", 0.0], 
  PARAMETER["central_meridian", 0.0], 
  PARAMETER["scale_factor", 1.0], 
  PARAMETER["false_easting", 0.0], 
  PARAMETER["false_northing", 0.0], 
  UNIT["m", 1.0], 
  AXIS["Easting", EAST], 
  AXIS["Northing", NORTH], 
  AUTHORITY["EPSG","3857"]]

 

 

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三、样例代码

import java.io.File;
import java.io.IOException;
import java.net.MalformedURLException;
import java.nio.charset.Charset;
import org.geotools.data.shapefile.ShapefileDataStore;
import org.geotools.data.shapefile.ShapefileDataStoreFactory;
import org.geotools.referencing.CRS;
import org.opengis.referencing.crs.CoordinateReferenceSystem;

public class ShapeUtils {

    /**
     * 获取Shape文件的坐标系信息。
     * 
     * @param shpFilePath shp文件路径
     * @return 坐标系的code ，例如3857,4326等等
     */
    public static Integer getEpsgCode(String shpFilePath) {

        ShapefileDataStore dataStore = buildDataStore(shpFilePath);
        Integer code = null;
        try {
            String wkt = dataStore.getSchema().getCoordinateReferenceSystem().toWKT();
            CoordinateReferenceSystem crsTarget = CRS.parseWKT(wkt);
            code = CRS.lookupEpsgCode(crsTarget,true);
            
        } catch (UnsupportedOperationException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            dataStore.dispose();
        }
        return code;
    }

    /**
     * 构建ShapeDataStore对象。
     * @param shpFilePath shape文件路径。
     * @return
     */
    public static ShapefileDataStore buildDataStore(String shpFilePath) {
        ShapefileDataStoreFactory factory = new ShapefileDataStoreFactory();
        try {
            ShapefileDataStore dataStore = (ShapefileDataStore) factory
                    .createDataStore(new File(shpFilePath).toURI().toURL());
            if (dataStore != null) {
                dataStore.setCharset(Charset.forName("UTF-8"));
            }
            return dataStore;
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return null;
    }
}

 

测试

import java.io.File;
import java.util.List;

import com.elon.model.ShapeFieldInfo;
import com.elon.model.gismodel.GisMultiPolygon;
import com.elon.shape.ShapeUtils;

public class StartupGeoTools {
    public static void main(String[] args) {

        String workSpacePath = System.getProperty("user.dir");
        String shpFilePath = workSpacePath + File.separator + "shape/ne_50m_admin_0_countries/ne_50m_admin_0_countries.shp";

        Integer code = ShapeUtils.getEpsgCode(shpFilePath);
        System.out.println("code:" + code);

    }
}

 

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参考网址

http://docs.geotools.org/stable/javadocs/org/geotools/referencing/CRS.html#getHorizontalCRS-org.opengis.referencing.crs.CoordinateReferenceSystem-

http://support.supermap.com.cn/DataWarehouse/WebDocHelp/iPortal/Appendix/CoordSystem/EPSGCode.htm