opengis-utils-for-java

name	opengis-utils-for-java
description	Use when needing common GIS utility functions in Java — CRS utilities, geometry helpers, format converters, spatial validation. OpenGIS Utils for Java: convenience toolkit for Java GIS projects.
tags	["java","gis","geotools","jts","gdal","geometry","vector","crs","cgcs2000"]

项目地址： https://github.com/znlgis/opengis-utils-for-java

官方文档： https://github.com/znlgis/opengis-utils-for-java#readme

Maven 坐标： com.znlgis.ogu4j:ogu4j:1.0.0

许可证： LGPL-2.1-or-later

概述

OGU4J (OpenGIS Utils for Java) is a unified Java GIS toolkit built on GeoTools, JTS, GDAL/OGR, and ESRI Geometry API. It provides:

• A unified layer model (OguLayer) for reading/writing GIS data across formats
• Geometry operations (60+ methods) via GeometryUtil
• Dual-engine architecture (GeoTools pure-Java & GDAL native)
• Coordinate reference system management (CGCS2000 built-in)

Java Version: 17+
Build Tool: Maven
Group ID: com.znlgis.ogu4j | Artifact ID: ogu4j | Version: 1.0.0

---

Project Structure

com.znlgis.ogu4j
├── datasource/                  # High-level data I/O
│   ├── OguLayerUtil             # ★ Primary entry point for reading/writing layers
│   └── GtTxtUtil                # National land TXT format support
├── engine/                      # GIS engine core
│   ├── GisEngine                # Engine interface
│   ├── GisEngineFactory         # Engine factory (auto-selects best engine)
│   ├── GeoToolsEngine           # GeoTools implementation (pure Java, always available)
│   ├── GdalEngine               # GDAL implementation (requires native GDAL)
│   ├── GeoToolsLayerReader/Writer  # GeoTools format I/O
│   ├── GdalLayerReader/Writer      # GDAL format I/O
│   ├── enums/                   # Enumerations
│   │   ├── DataFormatType       # SHP, GEOJSON, FILEGDB, POSTGIS, TXT, WKT, ESRIJSON, ARCSDE
│   │   ├── FieldDataType        # INTEGER, DOUBLE, STRING, BINARY, DATE, TIME, DATETIME, LONG
│   │   ├── GeometryType         # POINT, MULTIPOINT, LINESTRING, POLYGON, etc.
│   │   ├── GisEngineType        # GEOTOOLS, GDAL, AUTO
│   │   └── TopologyValidationErrorType
│   ├── io/                      # Reader/Writer interfaces
│   │   ├── LayerReader          # read(path, layerName, attributeFilter, spatialFilterWkt)
│   │   └── LayerWriter          # write(layer, path, layerName, options)
│   ├── model/
│   │   ├── layer/               # ★ Core data model
│   │   │   ├── OguLayer         # Layer: name, wkid, geometryType, fields, features
│   │   │   ├── OguFeature       # Feature: id, geometry (WKT), attributes
│   │   │   ├── OguField         # Field definition: name, alias, dataType, length
│   │   │   ├── OguFieldValue    # Field value with type conversion methods
│   │   │   ├── OguCoordinate    # Coordinate point (x, y, z)
│   │   │   ├── OguFeatureFilter # Functional interface for filtering
│   │   │   └── OguLayerMetadata # Extended metadata (CRS, projection, etc.)
│   │   ├── DbConnBaseModel      # PostGIS connection configuration
│   │   ├── GdbGroupModel        # FileGDB structure
│   │   ├── TopologyValidationResult
│   │   └── SimpleGeometryResult
│   └── util/
│       ├── CrsUtil              # Coordinate system management & transformation
│       ├── GeotoolsUtil         # GeoTools feature filtering
│       ├── OgrUtil              # GDAL/OGR initialization & resource management
│       ├── PostgisUtil          # PostGIS connection helpers
│       ├── ShpUtil              # Shapefile encoding & field name handling
│       └── GdalCmdUtil          # GDAL command-line wrapper (ogrinfo)
├── geometry/
│   └── GeometryUtil             # ★ 60+ geometry operation methods
├── exception/
│   ├── OguException             # Base checked exception
│   ├── DataSourceException      # Data source connection failures
│   ├── EngineNotSupportedException
│   ├── FormatParseException     # Format parsing failures
│   ├── LayerValidationException # Unchecked (RuntimeException)
│   └── TopologyException
└── utils/
    ├── ZipUtil                  # ZIP compress/decompress
    ├── EncodingUtil             # File encoding detection
    ├── SortUtil                 # Natural string sorting
    └── NumUtil                  # Number formatting (remove scientific notation)

---

Quick Reference: Common Tasks

1. Read a GIS Layer (Shapefile / GeoJSON / PostGIS / FileGDB / TXT)

import com.znlgis.ogu4j.datasource.OguLayerUtil;
import com.znlgis.ogu4j.engine.enums.DataFormatType;
import com.znlgis.ogu4j.engine.enums.GisEngineType;
import com.znlgis.ogu4j.engine.model.layer.OguLayer;

// Read Shapefile (GeoTools engine)
OguLayer layer = OguLayerUtil.readLayer(
    DataFormatType.SHP,          // format
    "/path/to/file.shp",        // path or connection string
    null,                        // layer name (null for single-layer formats)
    null,                        // attribute filter (CQL expression, e.g. "NAME = 'Beijing'")
    null,                        // spatial filter (WKT geometry)
    GisEngineType.AUTO           // engine: AUTO, GEOTOOLS, or GDAL
);

// Read GeoJSON
OguLayer layer = OguLayerUtil.readLayer(
    DataFormatType.GEOJSON, "/path/to/file.geojson",
    null, null, null, GisEngineType.GEOTOOLS
);

// Read FileGDB layer (requires GDAL)
OguLayer layer = OguLayerUtil.readLayer(
    DataFormatType.FILEGDB, "/path/to/data.gdb",
    "layerName", null, null, GisEngineType.GDAL
);

// Read PostGIS (use environment variables or secure config for credentials in production)
String connStr = "PG: host=localhost port=5432 dbname=gisdb user=postgres password=*** active_schema=public";
OguLayer   OguLayerUtil.readLayer(
    DataFormatType.POSTGIS, connStr,
    , , , GisEngineType.GEOTOOLS
);


 com.znlgis.ogu4j.datasource.GtTxtUtil;
   GtTxtUtil.loadTxt(, );  

2. Write a GIS Layer

import com.znlgis.ogu4j.datasource.OguLayerUtil;

// Write to Shapefile
OguLayerUtil.writeLayer(
    DataFormatType.SHP,
    layer,                       // OguLayer object
    "/path/to/output.shp",      // output path
    null,                        // layer name
    null,                        // options map (format-specific)
    GisEngineType.GEOTOOLS
);

// Write to GeoJSON
OguLayerUtil.writeLayer(
    DataFormatType.GEOJSON, layer,
    "/path/to/output.geojson", null, null, GisEngineType.GEOTOOLS
);

// Write to FileGDB (with options)
Map<String, Object> options = new HashMap<>();
options.put("featureDataset", "datasetName");
OguLayerUtil.writeLayer(
    DataFormatType.FILEGDB, layer,
    "/path/to/data.gdb", "layerName", options, GisEngineType.GDAL
);

// Write to PostGIS
OguLayerUtil.writeLayer(
    DataFormatType.POSTGIS, layer,
    connStr, "table_name", null, GisEngineType.GEOTOOLS
);

// Write National Land TXT
import com.znlgis.ogu4j.engine.model.layer.OguLayerMetadata;
OguLayerMetadata metadata = new OguLayerMetadata();
metadata.setCoordinateSystemName("2000国家大地坐标系");
metadata.setZoneDivision("3");
metadata.setProjectionType("高斯克吕格");
metadata.setMeasureUnit("米");
GtTxtUtil.saveTxt(layer, "/path/to/output.txt", metadata, null, 39);

3. Format Conversion (One-Step)

// SHP → GeoJSON
OguLayer layer = OguLayerUtil.readLayer(DataFormatType.SHP, shpPath, null, null, null, GisEngineType.AUTO);
OguLayerUtil.writeLayer(DataFormatType.GEOJSON, layer, geojsonPath, null, null, GisEngineType.AUTO);

// GeoJSON → PostGIS
OguLayer layer = OguLayerUtil.readLayer(DataFormatType.GEOJSON, geojsonPath, null, null, null, GisEngineType.AUTO);
OguLayerUtil.writeLayer(DataFormatType.POSTGIS, layer, connStr, "tableName", null, GisEngineType.AUTO);

4. Work with the Layer Model

import com.znlgis.ogu4j.engine.model.layer.*;
import com.znlgis.ogu4j.engine.enums.*;

// Create a layer from scratch
OguLayer layer = new OguLayer();
layer.setName("cities");
layer.setWkid(4490);  // CGCS2000 geographic
layer.setGeometryType(GeometryType.POINT);

// Define fields
List<OguField> fields = new ArrayList<>();
fields.add(new OguField("name", "城市名称", FieldDataType.STRING));
fields.add(new OguField("population", "人口", FieldDataType.INTEGER));
layer.setFields(fields);

// Create features
OguFeature feature = new OguFeature();
feature.setId("1");
feature.setGeometry("POINT(116.4 39.9)");  // WKT format
List<OguFieldValue> attrs = new ArrayList<>();
attrs.add(new OguFieldValue(fields.get(0), "北京"));
attrs.add(new OguFieldValue(fields.get(1), 21540000));
feature.setAttributes(attrs);
layer.setFeatures(List.of(feature));

// Validate layer
layer.validate();  // throws LayerValidationException if invalid

// Serialize to/from JSON
String json  layer.toJSON();
   OguLayer.fromJSON(json);


List<OguFeature> filtered = layer.filter(f -> {
       f.getAttribute().getIntValue();
     pop !=  && pop > ;  
});


   layer.getFeatures().get();
   f.getAttribute().getStringValue();
   f.getValue();
f.setValue(, );


   layer.getFeatureCount();
   layer.getFieldCount();

5. Geometry Operations (GeometryUtil)

import com.znlgis.ogu4j.geometry.GeometryUtil;
import org.locationtech.jts.geom.Geometry;

// === Format Conversions ===
Geometry geom = GeometryUtil.wkt2Geometry("POLYGON((0 0, 10 0, 10 10, 0 10, 0 0))");
String wkt = GeometryUtil.geometry2Wkt(geom);
String geojson = GeometryUtil.geometry2Geojson(geom);
String esriJson = GeometryUtil.geometry2EsriJson(geom, 4490);

// WKT ↔ GeoJSON
String geojson = GeometryUtil.wkt2Geojson(wkt);
String wkt = GeometryUtil.geojson2Wkt(geojson);

// WKT ↔ ESRI JSON
String esriJson = GeometryUtil.wkt2EsriJson(wkt, 4490);
String wkt = GeometryUtil.esriJson2Wkt(esriJson);

// GeoJSON ↔ ESRI JSON
String esriJson = GeometryUtil.geoJson2EsriJson(4490, geojson);
String geojson = GeometryUtil.esriJson2GeoJson(esriJson);

// GeoJSON / ESRI JSON → JTS Geometry
Geometry geom = GeometryUtil.geojson2Geometry(geojson);
Geometry geom = GeometryUtil.esriJson2Geometry(esriJson);

// === Spatial Relations (JTS Geometry-based) ===
   GeometryUtil.intersects(geomA, geomB);
   GeometryUtil.contains(geomA, geomB);
   GeometryUtil.within(geomA, geomB);
   GeometryUtil.touches(geomA, geomB);
   GeometryUtil.crosses(geomA, geomB);
   GeometryUtil.overlaps(geomA, geomB);
   GeometryUtil.disjoint(geomA, geomB);
   GeometryUtil.relate(geomA, geomB);
   GeometryUtil.relatePattern(geomA, geomB, );


   GeometryUtil.buffer(geom, );
   GeometryUtil.intersection(geomA, geomB);
   GeometryUtil.union(geomA, geomB);   
   GeometryUtil.difference(geomA, geomB);
   GeometryUtil.symDifference(geomA, geomB);
   GeometryUtil.convexHull(geom);
   GeometryUtil.concaveHull(geom);
   GeometryUtil.splitPolygon(polygon, line);
   GeometryUtil.polygonize(geom);


   GeometryUtil.area(geom);
   GeometryUtil.length(geom);
   GeometryUtil.distance(geomA, geomB);
   GeometryUtil.isWithinDistance(geomA, geomB, );
   GeometryUtil.centroid(geom);
   GeometryUtil.interiorPoint(geom);
   GeometryUtil.boundary(geom);
   GeometryUtil.envelope(geom);
   GeometryUtil.dimension(geom);
   GeometryUtil.numPoints(geom);
   GeometryUtil.isEmpty(geom);
   GeometryUtil.geometryType(geom);


   GeometryUtil.isValid(geom);


   GeometryUtil.isSimple(geom);


   GeometryUtil.validate(geom);  


   GeometryUtil.simplify(geom, );
   GeometryUtil.densify(geom, );


   GeometryUtil.equalsExact(geomA, geomB);
   GeometryUtil.equalsExactTolerance(geomA, geomB, );
   GeometryUtil.equalsNorm(geomA, geomB);
   GeometryUtil.equalsTopo(geomA, geomB);

6. WKT-Based Geometry Operations (ESRI Geometry API)

These methods work directly with WKT strings, without creating JTS Geometry objects. Useful when geometry data is in WKT format. Method names end with Wkt.

// Spatial relations (require wkid for coordinate system context)
boolean result = GeometryUtil.intersectsWkt(wktA, wktB, 4490);
boolean result = GeometryUtil.containsWkt(wktA, wktB, 4490);
boolean result = GeometryUtil.withinWkt(wktA, wktB, 4490);
boolean result = GeometryUtil.touchesWkt(wktA, wktB, 4490);
boolean result = GeometryUtil.crossesWkt(wktA, wktB, 4490);
boolean result = GeometryUtil.overlapsWkt(wktA, wktB, 4490);
boolean result = GeometryUtil.disjointWkt(wktA, wktB, 4490);
boolean result = GeometryUtil.equalsWkt(wktA, wktB, 4490);
boolean result = GeometryUtil.relatePatternWkt(wktA, wktB, 4490, "T*T***FF*");

// Spatial analysis (returns WKT strings)
String buffer = GeometryUtil.bufferWkt(wkt, 4490, 100.0);
String intersection = GeometryUtil.intersectionWkt(wktA, wktB, 4490);
String union  GeometryUtil.unionWkt(wktList, );  
   GeometryUtil.differenceWkt(wktA, wktB, );
   GeometryUtil.symDifferenceWkt(wktA, wktB, );
   GeometryUtil.convexHullWkt(wkt);
   GeometryUtil.boundaryWkt(wkt);


   GeometryUtil.areaWkt(wkt);
   GeometryUtil.lengthWkt(wkt);
   GeometryUtil.distanceWkt(wktA, wktB, );
   GeometryUtil.centroidWkt(wkt);
   GeometryUtil.dimensionWkt(wkt);
   GeometryUtil.isEmptyWkt(wkt);
   GeometryUtil.geometryTypeWkt(wkt);
   GeometryUtil.isSimpleWkt(wkt, );


   GeometryUtil.simplifyWkt(wkt, );

7. Coordinate Reference System (CrsUtil)

import com.znlgis.ogu4j.engine.util.CrsUtil;

// Transform WKT geometry between coordinate systems
String transformedWkt = CrsUtil.transform(wkt, 4490, 4528);  // CGCS2000 geo → CGCS2000 / 3-degree zone 39

// Transform JTS Geometry
Geometry transformed = CrsUtil.transform(geometry, 4490, 4528);

// Reproject an entire layer
OguLayer reprojected = CrsUtil.reproject(layer, 4528);

// Get zone number
int zoneNumber = CrsUtil.getDh(geometry);  // from JTS Geometry
int zoneNumber = CrsUtil.getDh(wkt);       // from WKT string
int zoneNumber = CrsUtil.getDh(4528);      // from projected WKID

// Get WKID for geometry
Integer wkid = CrsUtil.getWkid(geometry);

// Get projected WKID from zone number
Integer projectedWkid = CrsUtil.getProjectedWkid(39);          // zone number
Integer projectedWkid = CrsUtil.getProjectedWkid(geometry);    // from geometry

// Check CRS type
   CrsUtil.isProjectedCRS(crs);


   CrsUtil.getTolerance();


Map<Integer, CoordinateReferenceSystem> crsList = CrsUtil.getSupportedCRSList();
Map.Entry<Integer, CoordinateReferenceSystem> entry = CrsUtil.getSupportedCRS();

8. Engine API (Advanced Usage)

import com.znlgis.ogu4j.engine.*;
import com.znlgis.ogu4j.engine.enums.*;

// Get engine via factory
GisEngine engine = GisEngineFactory.getEngine(GisEngineType.AUTO);
GisEngine engine = GisEngineFactory.getEngine(DataFormatType.GEOJSON);  // auto-select
GisEngine engine = GisEngineFactory.getEngine(GisEngineType.GEOTOOLS, DataFormatType.SHP);

// Check engine capabilities
boolean available = engine.isAvailable();
boolean supports = engine.supports(DataFormatType.FILEGDB);

// Read/write via engine
OguLayer layer = engine.readLayer(DataFormatType.SHP, path, layerName, attrFilter, spatialFilter);
engine.writeLayer(DataFormatType.SHP, layer, path, layerName, options);

// Get reader/writer directly
LayerReader reader = engine.getReader(DataFormatType.GEOJSON);
LayerWriter writer = engine.getWriter(DataFormatType.GEOJSON);
OguLayer layer = reader.read(path, layerName, attrFilter, spatialFilterWkt);
writer.write(layer, path, layerName, options);

9. Utility Classes

// ZIP operations
import com.znlgis.ogu4j.utils.ZipUtil;
ZipUtil.zip(folder, "output.zip");                           // default GBK encoding
ZipUtil.zip(folder, "output.zip", StandardCharsets.UTF_8);   // custom encoding
ZipUtil.unzip("input.zip", destPath);
ZipUtil.unzip(zipFile, destPath);

// File encoding detection
import com.znlgis.ogu4j.utils.EncodingUtil;
Charset charset = EncodingUtil.getFileEncoding(file);  // detects UTF-8, GBK, GB2312, GB18030

// Natural sorting (handles numbers within strings)
import com.znlgis.ogu4j.utils.SortUtil;
int cmp = SortUtil.compareString("item2", "item10");  // returns negative (2 < 10)

// Remove scientific notation
import com.znlgis.ogu4j.utils.NumUtil;
String plain = NumUtil.getPlainString(1.234E10);  // "12340000000"

// FileGDB structure inspection (requires GDAL)
import com.znlgis.ogu4j.engine.util.GdalCmdUtil;
GdbGroupModel structure = GdalCmdUtil.getGdbDataStructure("/path/to/data.gdb");

// PostGIS helpers
import com.znlgis.ogu4j.engine.util.PostgisUtil;
String gdalConn = PostgisUtil.toGdalPostgisConnStr(dbConnModel);
JDBCDataStore ds = PostgisUtil.getGeotoolsPostgisDataSource(dbConnModel);


 com.znlgis.ogu4j.engine.util.ShpUtil;
ShpUtil.formatFieldName(fields);                   
   ShpUtil.check();  

---

Data Format Support Matrix

Format	DataFormatType	GeoTools	GDAL	Read	Write	Notes
Shapefile	SHP	✅	✅	✅	✅	Field names limited to 10 chars
GeoJSON	GEOJSON	✅	✅	✅	✅
FileGDB	FILEGDB	❌	✅	✅	✅	Requires GDAL native library
PostGIS	POSTGIS	✅	✅	✅	✅	Connection string as path
National Land TXT	TXT	✅	❌	✅	✅	Use GtTxtUtil directly
WKT	WKT	✅	❌	✅	❌	Geometry-only format
ESRI JSON	ESRIJSON	❌	❌	✅*	❌	*Via GeometryUtil conversion

---

Data Model Reference

OguLayer (Core)

Property	Type	Description
name	String	Layer name
alias	String	Layer display name
wkid	Integer	EPSG code (e.g. 4490 for CGCS2000)
geometryType	GeometryType	POINT, POLYGON, LINESTRING, etc.
tolerance	Double	Geometric tolerance
fields	List<OguField>	Field definitions
features	List<OguFeature>	Feature collection
metadata	OguLayerMetadata	Extended metadata

Methods: fromJSON(String), toJSON(), validate(), filter(OguFeatureFilter), getFeatureCount(), getFieldCount()

OguFeature

Property	Type	Description
id	String	Feature identifier
geometry	String	Geometry in WKT format
attributes	List<OguFieldValue>	Attribute values
coordinates	List<OguCoordinate>	Coordinate points (TXT format)
rawValues	List<String>	Raw values (TXT format)

Methods: getAttribute(String fieldName), getValue(String fieldName), setValue(String fieldName, Object value)

OguField

Property	Type	Description
name	String	Field name
alias	String	Display name
description	String	Description
dataType	FieldDataType	INTEGER, DOUBLE, STRING, DATE, etc.
length	Integer	Max length (for STRING)
nullable	Boolean	Nullable flag
defaultValue	Object	Default value

Constructors: OguField(name, alias, dataType), OguField(name, alias, description, dataType)

OguFieldValue

Property	Type	Description
field	OguField	Field definition
value	Object	Raw value

Methods: getFieldName(), getStringValue(), getIntValue(), getDoubleValue()

OguCoordinate

Property	Type	Description
x	Double	X coordinate (longitude)
y	Double	Y coordinate (latitude)
z	Double	Z coordinate (elevation, optional)
pointNumber	String	Point identifier
ringNumber	Integer	Ring/loop number

Constructors: OguCoordinate(x, y), OguCoordinate(x, y, z)

DbConnBaseModel (PostGIS connection)

Property	Type	Description
dbType	String	Database type
host	String	Host address
port	String	Port number
schema	String	Schema name
database	String	Database name
user	String	Username
passwd	String	Password

---

Enumerations Quick Reference

GeometryType

POINT, MULTIPOINT, LINESTRING, LINEARRING, MULTILINESTRING, POLYGON, MULTIPOLYGON, GEOMETRYCOLLECTION

Lookup methods: valueOfByTypeName(String), valueOfByTypeCode(int), valueOfByTypeClass(Class<?>), valueOfByWkbGeometryType(int)

FieldDataType

INTEGER, DOUBLE, STRING, BINARY, DATE, TIME, DATETIME, LONG

Lookup methods: fieldDataTypeByGdalCode(int), fieldDataTypeByTypeClass(Class<?>)

DataFormatType

WKT, GEOJSON, ESRIJSON, SHP, TXT, FILEGDB, POSTGIS, ARCSDE

Properties per value: desc (description), gdalDriverName (GDAL driver name)

GisEngineType

GEOTOOLS, GDAL, AUTO

---

Exception Hierarchy

Exception
└── OguException                      # Base checked exception
    ├── DataSourceException           # Data source connection/access failure
    ├── EngineNotSupportedException   # Engine doesn't support the operation/format
    ├── FormatParseException          # Data format parsing failure
    └── TopologyException             # Geometry topology error

RuntimeException
└── LayerValidationException          # Layer data validation failure (unchecked)

---

Architecture & Design Patterns

• Factory Pattern: GisEngineFactory creates engine instances; use GisEngineType.AUTO for automatic selection (prefers GDAL if available)
• Strategy Pattern: LayerReader / LayerWriter interfaces define pluggable format-specific I/O strategies
• Adapter Pattern: GisEngine provides a unified API over GeoTools and GDAL
• Functional Interface: OguFeatureFilter enables lambda-based feature filtering
• Geometry is WKT: Features store geometry as WKT strings in OguFeature.geometry; use GeometryUtil for conversion/operations

---

AI 使用建议

推荐工作流

1. 选择引擎：GisEngineType.AUTO 自动选择最优引擎（GDAL 优先）
2. 读取数据：使用 OguLayerUtil.readLayer() 统一入口读取各类矢量格式
3. 空间分析：JTS Geometry 对象用 GeometryUtil（60+ 方法），WKT 字符串用 *Wkt 后缀方法
4. 坐标转换：使用 CrsUtil.transform() 进行 CGCS2000 系列坐标系变换
5. 写出结果：使用 OguLayerUtil.writeLayer() 写出为目标格式

关键注意事项

• 始终使用 OguLayerUtil 作为主入口：自动处理引擎选择和格式路由
• 几何以 WKT 存储：OguFeature.geometry 存储 WKT 字符串；空间运算时转为 JTS Geometry
• 引擎选择：GEOTOOLS（纯 Java，无原生依赖）vs GDAL（需本地库，支持 FileGDB）
• CGCS2000 坐标系：EPSG:4490 为默认地理 CRS，投影 CRS 范围 EPSG:4502-4554
• Shapefile 字段名限 10 字符：使用 ShpUtil.formatFieldName() 自动截断
• 资源释放：DataStore 和 OGR DataSource 必须在 finally 块中释放

Important Notes for AI Developers

1. Always use OguLayerUtil as the primary entry point for reading/writing GIS data. It handles engine selection and format routing.

2. Geometry in features is stored as WKT strings. Convert to JTS Geometry objects via GeometryUtil.wkt2Geometry() when you need spatial operations.

3. Engine selection:

   • GisEngineType.AUTO — library auto-selects (prefers GDAL if available)
   • GisEngineType.GEOTOOLS — pure Java, always available, no native dependencies
   • GisEngineType.GDAL — requires native GDAL library installed; needed for FileGDB format

4. CGCS2000 coordinate system (EPSG:4490) is the default/primary CRS. Projected CRS range: EPSG 4502-4554 (3-degree zones). Use CrsUtil for transformation.

5. PostGIS connection strings follow the format: "PG: host=<host> port=<port> dbname=<db> user=<user> password=<pwd> active_schema=<schema>"

6. Resource management:

   • DataStore objects (ShapefileDataStore, JDBCDataStore) must be disposed in finally blocks
   • OGR DataSource objects must be closed via OgrUtil.closeDataSource()

7. Shapefile field names are limited to 10 characters. Use ShpUtil.formatFieldName() to auto-truncate.

8. OguLayer can be serialized to/from JSON using layer.toJSON() and OguLayer.fromJSON(json) (backed by FastJSON2).

9. Attribute filtering uses CQL expression syntax (e.g., "population > 1000000 AND name LIKE '%京%'").

10. Spatial filtering accepts WKT geometry strings (e.g., "POLYGON((115 39, 117 39, 117 41, 115 41, 115 39))").

11. Two geometry operation styles:

    • JTS-based: Pass Geometry objects, get Geometry back (e.g., GeometryUtil.buffer(geom, dist))
    • WKT-based (suffix Wkt): Pass WKT strings and WKID, get WKT back (e.g., )

---

相关技能

• geotools — Java GIS 工具库：../geotools/SKILL.md
• jts — JTS Topology Suite：../jts/SKILL.md
• geometry-api-java — Esri Geometry API：../geometry-api-java/SKILL.md
• gdal — 命令行数据处理：../gdal/SKILL.md
• gdal-api — GDAL 编程 API：../gdal-api/SKILL.md

Typical Workflow Example

import com.znlgis.ogu4j.datasource.OguLayerUtil;
import com.znlgis.ogu4j.engine.enums.*;
import com.znlgis.ogu4j.engine.model.layer.*;
import com.znlgis.ogu4j.engine.util.CrsUtil;
import com.znlgis.ogu4j.geometry.GeometryUtil;
import org.locationtech.jts.geom.Geometry;

// Step 1: Read a Shapefile
OguLayer layer = OguLayerUtil.readLayer(
    DataFormatType.SHP, "/data/parcels.shp",
    null, null, null, GisEngineType.AUTO
);

// Step 2: Filter features by area > 10,000 square units
List<OguFeature> largeParcels = layer.filter(f -> {
    Geometry geom = GeometryUtil.wkt2Geometry(f.getGeometry());
    return GeometryUtil.area(geom) > 10000;
});

// Step 3: Buffer each geometry
for (OguFeature f : largeParcels) {
    Geometry geom = GeometryUtil.wkt2Geometry(f.getGeometry());
    Geometry buffered = GeometryUtil.buffer(geom, 50.0);
    f.setGeometry(GeometryUtil.geometry2Wkt(buffered));
}

// Step 4: Reproject to projected CRS
OguLayer projected = CrsUtil.reproject(layer, 4528);

// Step 5: Export to GeoJSON
OguLayerUtil.writeLayer(
    DataFormatType.GEOJSON, projected,
    "/data/output.geojson", null, null, GisEngineType.AUTO
);