坐标转换-使用geotools读取和转换地理空间表的坐标系（sqlserver、postgresql）

前言：

业务上通过GIS软件将空间数据导入到数据库时，因为不同的数据来源和软件设置，可能导入到数据库的空间表坐标系是各种各样的。
如果要把数据库空间表发布到geoserver并且统一坐标系，只是在geoserver单纯的设置坐标系只是改了定义并没有实际执行坐标转换，所以需要在数据库层面统一好坐标系，再发布到geoserver。

1,开发前准备

1.1,数据准备

要准备测试数据，可以参考 地理空间表的导入。
我这里使用arcgis pro导入sqlserver，如果导入postgresql需要企业数据库才行，也就是需要离线证书，比较麻烦。
我先导入一个4524的投影坐标，测试转换为4490

1.2,环境准备

坐标转换需要先读取数据库的空间表原坐标系，在根据原坐标系转换为目标坐标系。
使用的转换工具是geotool。
pom引入必要的依赖，geotools版本是24.3

<dependency><groupId>org.geotools</groupId><artifactId>gt-main</artifactId><version>${geotools.version}</version>
</dependency>
<dependency><groupId>org.geotools</groupId><artifactId>gt-jdbc</artifactId><version>${geotools.version}</version></dependency><dependency><groupId>org.geotools.jdbc</groupId><artifactId>gt-jdbc-sqlserver</artifactId><version>${geotools.version}</version></dependency><dependency><groupId>org.geotools.jdbc</groupId><artifactId>gt-jdbc-postgis</artifactId><version>${geotools.version}</version></dependency>

2,读取空间表原坐标系

要使用geotool读取空间表的坐标系，需要先使用geotool提供的方法创建DataStore,官网有一个示例代码
https://docs.geotools.org/latest/userguide/library/jdbc/sqlserver.html

java.util.Map params = new java.util.HashMap();
params.put( "dbtype", "sqlserver");   //（巨坑）
params.put( "host", "localhost");
params.put( "port", 4866);
params.put( "user", "geotools");
params.put( "passwd", "geotools");
DataStore dataStore=DataStoreFinder.getDataStore(params);

这是一个坑，官方说明是版本14之后支持Microsoft JDBC driver，dbtype应该就不需要使用jtds前缀了，实际上不加必报错

先写一个测试方法，传入数据库连接信息，表名，数据库类型，返回原表坐标系

import org.geotools.data.DataStore;
import org.geotools.data.DataStoreFinder;
import org.geotools.data.simple.SimpleFeatureSource;
import org.geotools.jdbc.JDBCDataStoreFactory;
import org.opengis.feature.simple.SimpleFeatureType;
import org.opengis.referencing.crs.CoordinateReferenceSystem;public static int getEpsg(DatabaseConfig databaseConfig, String tableName) {DataStore dataStore = null;try {Map<String, Object> params = new HashMap<>();
//        params.put(JDBCDataStoreFactory.SCHEMA.key, "dbo");if (DatabaseType.SQLSERVER.equals(databaseConfig.getDatabaseType())) {params.put(JDBCDataStoreFactory.DBTYPE.key, "jtds-sqlserver");} else {params.put(JDBCDataStoreFactory.DBTYPE.key, "jtds-postgis");}params.put(JDBCDataStoreFactory.HOST.key, databaseConfig.getHost());params.put(JDBCDataStoreFactory.PORT.key, databaseConfig.getPort());params.put(JDBCDataStoreFactory.DATABASE.key, databaseConfig.getDatabaseName());params.put(JDBCDataStoreFactory.USER.key, databaseConfig.getUsername());params.put(JDBCDataStoreFactory.PASSWD.key, databaseConfig.getPassword());dataStore = DataStoreFinder.getDataStore(params);if (dataStore == null) {System.out.println("Failed to connect to the database.");return -1;}// Get the feature source for the "aa" tableSimpleFeatureSource featureSource = dataStore.getFeatureSource(tableName);// Get the feature type and its CRSSimpleFeatureType featureType = featureSource.getSchema();CoordinateReferenceSystem crs = featureType.getCoordinateReferenceSystem();// Print the CRS detailsif (crs != null) {System.out.println("Spatial Reference System: " + crs.getName());System.out.println("EPSG Code: " + crs.getName().getCode());System.out.println("crs : " + crs.toString());//抽取原表坐标系int result = extractEPSG(crs.toString());System.out.println("Result: " + result);return result;}// Close the data storedataStore.dispose();return 0;} catch (IOException e) {log.error("查询空间表坐标系异常：{}", e.toString());return -1;} finally {if (dataStore != null) {dataStore.dispose();}}}

然后看一下解析出来坐标信息

Spatial Reference System: EPSG:CGCS2000 / 3-degree Gauss-Kruger zone 36
EPSG Code: CGCS2000 / 3-degree Gauss-Kruger zone 36
crs : PROJCS["CGCS2000 / 3-degree Gauss-Kruger zone 36", GEOGCS["China Geodetic Coordinate System 2000", DATUM["China 2000", SPHEROID["CGCS2000", 6378137.0, 298.257222101, AUTHORITY["EPSG","1024"]], AUTHORITY["EPSG","1043"]], PRIMEM["Greenwich", 0.0, AUTHORITY["EPSG","8901"]], UNIT["degree", 0.017453292519943295], AXIS["Geodetic latitude", NORTH], AXIS["Geodetic longitude", EAST], AUTHORITY["EPSG","4490"]], PROJECTION["Transverse_Mercator", AUTHORITY["EPSG","9807"]], PARAMETER["central_meridian", 108.0], PARAMETER["latitude_of_origin", 0.0], PARAMETER["scale_factor", 1.0], PARAMETER["false_easting", 36500000.0], PARAMETER["false_northing", 0.0], UNIT["m", 1.0], AXIS["Northing", NORTH], AXIS["Easting", EAST], AUTHORITY["EPSG","4524"]]

我想要的是之前我们在arcgis pro中看到的投影坐标，位于crs信息的最后一个EPSG内，针对crs信息写一个方法解析出epsg

    public static int extractEPSG(String input) {Pattern pattern = Pattern.compile("AUTHORITY\\[\"EPSG\",\"(\\d+)\"\\]");Matcher matcher = pattern.matcher(input);int lastEPSG = 0;while (matcher.find()) {lastEPSG = Integer.parseInt(matcher.group(1));}return lastEPSG;}

3,执行坐标转换

我这里目标坐标系写死，因为系统需要插入到sqlserver中的都要统一坐标系，所以直接在原表更新了。
如果要保留原表信息可以复制表在副本表更新坐标。
sqlserver与postgresql中空间函数有些差异，需要区分处理。

/*** 地理空间表坐标转换** @param sourceEpsg     原表坐标系* @param config         数据库连接信息* @param tableName      表名  dbo.ROAD* @param geometryColumn 空间字段*/public static void epsgTo4490(int sourceEpsg, DatabaseConfig config, String tableName, String geometryColumn) {String sourceEPSG = "EPSG:" + sourceEpsg;String targetEPSG = "EPSG:4490";ResultSet resultSet = null;try (Connection connection = DatabaseConnection.getConnection(config)) {//拼接sqlString sql;if (config.getDatabaseType().SQLSERVER.equals(config.getDatabaseType())) {sql = "SELECT " + geometryColumn + ".STAsText() as Shape,OBJECTID FROM " + tableName;} else {//ST_AsText(columns)sql = "SELECT ST_AsText(" + geometryColumn + ") as Shape,OBJECTID FROM " + tableName;}// 使用连接执行 SQL 查询操作PreparedStatement statement = connection.prepareStatement(sql);resultSet = statement.executeQuery();// Create MathTransformCRSFactory crsFactory = new CRSFactory();org.osgeo.proj4j.CoordinateReferenceSystem sourceCRS = crsFactory.createFromName(sourceEPSG);org.osgeo.proj4j.CoordinateReferenceSystem targetCRS = crsFactory.createFromName(targetEPSG);CoordinateTransformFactory transformFactory = new CoordinateTransformFactory();CoordinateTransform transform = transformFactory.createTransform(sourceCRS, targetCRS);// Process each row of the result setwhile (resultSet.next()) {String shape = resultSet.getString("Shape");int objectId = resultSet.getInt("OBJECTID");// Convert the string representation of the geometry to a JTS Geometry objectWKTReader reader = new WKTReader();Geometry geometry = reader.read(shape);// Perform the coordinate transformation for each coordinate in the geometryfor (int i = 0; i < geometry.getCoordinates().length; i++) {Coordinate srcCoord = geometry.getCoordinates()[i];ProjCoordinate targetCoord = new ProjCoordinate(srcCoord.getX(), srcCoord.getY());transform.transform(targetCoord, targetCoord); // 将源坐标转换为目标坐标，并保存在 targetCoord 中srcCoord.setX(targetCoord.x);srcCoord.setY(targetCoord.y);}// Convert the transformed geometry back to a stringWKTWriter writer = new WKTWriter();String transformedShape = writer.write(geometry);// Update the original table with the transformed geometry using the primary keyString updateSQL;if (DatabaseType.SQLSERVER.equals(config.getDatabaseType())) {updateSQL = "UPDATE " + tableName + " SET " + geometryColumn + " = ? WHERE OBJECTID = ?";} else {//UPDATE "public"."ROAD" SET Shape = ST_SetSRID(ST_GeomFromText("Shape"), 4490);updateSQL = "UPDATE " + tableName + " SET " + geometryColumn + " = ST_SetSRID(?,4490) WHERE OBJECTID = ?";}statement = connection.prepareStatement(updateSQL);statement.setString(1, transformedShape);statement.setInt(2, objectId);statement.executeUpdate();statement.clearParameters();}if (DatabaseType.SQLSERVER.equals(config.getDatabaseType())) {//修复多边形错误   UPDATE dbo.ROAD SET Shape = Shape.MakeValid()String updateSQL = "UPDATE " + tableName + " SET " + geometryColumn + " = " + geometryColumn + ".MakeValid()";statement = connection.prepareStatement(updateSQL);statement.executeUpdate();//指定坐标系 UPDATE dbo.ROAD SET Shape.STSrid=4490updateSQL = "UPDATE " + tableName + " SET " + geometryColumn + ".STSrid=4490";statement = connection.prepareStatement(updateSQL);statement.executeUpdate();}// Close the resourcesstatement.close();resultSet.close();} catch (SQLException e) {log.error("坐标转换中sql执行异常：{}", e.getMessage());} catch (ParseException e) {log.error("坐标转换中异常：{}", e.getMessage());}}

上述代码只是sqlservcer亲测多种坐标系转换正常，且转换后的表发布到geoserver和arcgis都能正常预览且聚焦位置正确，postgresql还有待测试

4,单元测试

    public static void main(String[] args) throws SQLException {String tableName = "ROAD";//测试sqlserverDatabaseConfig databaseConfig = new DatabaseConfig(DatabaseType.SQLSERVER, "127.0.0.1", 1433, "测试中文数据库", "sa", "xxxx");//测试postgresql//DatabaseConfig databaseConfig = new DatabaseConfig(DatabaseType.POSTGRESQL, "127.0.0.1", 5432, "postgis20", "postgres", "xxxxxxx");int sourceEpsg = TableEpsgUtil.getEpsg(databaseConfig, tableName);System.out.println("原表坐标：" + sourceEpsg);//如果获取到原表坐标并且不是4490,则执行转换if (sourceEpsg > 0 && sourceEpsg != 4490) {epsgTo4490(sourceEpsg, databaseConfig, tableName, "Shape");System.out.println("坐标转换完成");}}