在入库和查询中需要自动的让geometry的类型和实体类中的类型映射。

实体类中接收参数是String类型（geoJson）

PostGis中的geometry类型是十六进制的扩展WKB类型（EWKB），

虽然Postgis数据库中提供类类型转换函数，能转换各种类型postgis常用命令_yaoct的博客-CSDN博客

但是基于mybatis框架查询时，就需要用java代码来转换。初步方案时mybatis中的类型转换器。

先引入java处理GIS的库，这里用的是Geotools库。

1.java代码中数据类型的转换

geotools的maven引入：

<!-- geotools的远程库 --><repositories><repository><id>osgeo</id><name>OSGeo Release Repository</name><url>https://repo.osgeo.org/repository/release/</url><snapshots><enabled>false</enabled></snapshots><releases><enabled>true</enabled></releases></repository><repository><id>osgeo-snapshot</id><name>OSGeo Snapshot Repository</name><url>https://repo.osgeo.org/repository/snapshot/</url><snapshots><enabled>true</enabled></snapshots><releases><enabled>false</enabled></releases></repository></repositories><dependencies><!--geotool https://docs.geotools.org/latest/userguide/tutorial/quickstart/maven.html--><dependency><groupId>org.geotools</groupId><artifactId>gt-geojson</artifactId><version>${geotools.version}</version></dependency><dependency><groupId>org.geotools</groupId><artifactId>gt-main</artifactId><version>${geotools.version}</version></dependency><dependency><groupId>org.geotools</groupId><artifactId>gt-opengis</artifactId><version>${geotools.version}</version></dependency><dependency><groupId>org.geotools</groupId><artifactId>gt-referencing</artifactId><version>${geotools.version}</version></dependency><dependency><groupId>org.geotools</groupId><artifactId>gt-metadata</artifactId><version>${geotools.version}</version></dependency><dependency><groupId>org.geotools</groupId><artifactId>gt-epsg-hsql</artifactId><version>${geotools.version}</version></dependency></dependencies>

Geotools工具类转换WKB和Geojson

WKBReader reader = new WKBReader( );Geometry geometry = reader.read(WKBReader.hexToBytes("0101000020E61000002C39382229FD5D4085716007088C3E40"));// 设置保留6位小数，否则GeometryJSON默认保留4位小数GeometryJSON geometryJson = new GeometryJSON(7);String s = geometryJson.toString(geometry);System.out.println(s);//{"type":"Point","coordinates":[119.9556356,30.5469975]}//EWKB->转geojson丢失信息Geometry read = geometryJson.read("{\"type\":\"Point\",\"coordinates\":[119.9556356,30.5469975]}");System.out.println(read.toString());WKBWriter wkbWriter = new WKBWriter();byte[] write = wkbWriter.write(geometry);String s1 = WKBWriter.toHex(write);System.out.println(s1);

2.mybatis-plus类型转换器

这里框架用的是mybatis-plus,所有使用转换时，mybatis-plus中的实体类也要配置一些转换注解，其他和mybaitis中的xml配置属性相同。参考

MyBatis Plus 自动类型转换之TypeHandler


@Data
@ToString
@TableName (value = "test_table",autoResultMap = true)
@ApiModel ("test")
public class TestTable  implements Serializable {private static final long serialVersionUID =  8881418345724766899L;@TableId(value = "id")private Integer id;@ApiModelProperty(value = "二进制WKB数据")@TableField(value = "position",typeHandler = WKB2GeoJsonTypeHandler.class)@JsonRawValueprivate String position;@TableField("name")private String name;}

mybatis-plus配置添加转换器包路径，类似mybatis，之后用于写xml中sql

mybatis-plus:type-handlers-package: com.zjzy.mapper.typehandlerconfiguration:map-underscore-to-camel-case: trueauto-mapping-behavior: fulllog-impl: org.apache.ibatis.logging.stdout.StdOutImplmapper-locations: classpath*:mapper/**/*Mapper.xml

3.mybatis类型转换器转换geometry格式

因为缺少JDBC映射，数据库开始报错：‘类型为 geometry, 但表达式的类型为 character varying’

参考：Mybatis-plus读取和保存Postgis geometry数据 - 简书

应该是缺少JDBC-type类型。引入响应的postGIS驱动

添加maven包：

        <!-- 这里会补充mybatis缺少的JDBC-Type如postGis中的geometry类型 --><dependency><groupId>net.postgis</groupId><artifactId>postgis-jdbc</artifactId><version>2.5.0</version></dependency>

类型转换器代码：

package com.zjzy.mapper.typehandler;import com.zjzy.mapper.CommonCodeMapper;
import com.zjzy.util.SpringContextUtil;
import lombok.extern.slf4j.Slf4j;
import org.apache.ibatis.type.JdbcType;
import org.apache.ibatis.type.MappedJdbcTypes;
import org.apache.ibatis.type.MappedTypes;
import org.apache.ibatis.type.TypeHandler;
import org.geotools.geojson.geom.GeometryJSON;
import org.geotools.geometry.jts.WKBReader;
import org.locationtech.jts.geom.Geometry;
import org.locationtech.jts.io.ParseException;
import org.postgis.PGgeometry;import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Set;/*** @version 2.0* @description* @Author yaoct* @create 2021/12/22 16:19*/
@Slf4j
public class WKB2GeoJsonTypeHandler implements TypeHandler<String> {/*** 插入数据，转换,geoJson2EWKB* @param ps* @param i* @param parameter* @param jdbcType* @throws SQLException*/@Overridepublic void setParameter(PreparedStatement ps, int i, String parameter, JdbcType jdbcType) throws SQLException {
//EWKB是pg数据库自定义的类型，所以需要用数据库函数,插入数据库一般次数较少，这样并不会对数据库造成过大负担
//        CommonCodeMapper mapper = SpringContextUtil.getBean(CommonCodeMapper.class);
//        String EWKB = mapper.geo2EWKB(parameter);
//        PGgeometry ewkb = new PGgeometry(EWKB);
//        ps.setObject(i,ewkb);//通过geoTool转换WKBGeometryJSON geometryJson = new GeometryJSON(7);Geometry read = null;try {read = geometryJson.read(parameter);} catch (IOException e) {e.printStackTrace();}
//        System.out.println(read.toString());read.setSRID(4326);
//        GeometryJSON geometryJson = new GeometryJSON(7);WKBWriter wkbWriter = new WKBWriter(2, ByteOrderValues.BIG_ENDIAN,true);byte[] write = wkbWriter.write(read);String s1 = WKBWriter.toHex(write);PGgeometry ewkb = new PGgeometry(s1);ps.setObject(i,ewkb);}/*** 取出数据转换,WKB->Geojson* @param rs* @param columnName* @return* @throws SQLException*/@Overridepublic String getResult(ResultSet rs, String columnName) throws SQLException {String WKB = rs.getString(columnName);if(WKB==null){return null;}WKBReader reader = new WKBReader( );Geometry geometry = null;try {geometry = reader.read(WKBReader.hexToBytes(WKB));} catch (ParseException e) {//转换失败return null;}//转换成4326try {int srid = geometry.getSRID();CoordinateReferenceSystem sourceCRS = CRS.decode("EPSG:"+srid,true);CoordinateReferenceSystem targetCRS = CRS.decode("EPSG:4326",true);MathTransform transform = CRS.findMathTransform(sourceCRS, targetCRS,true);geometry = JTS.transform(geometry, transform);} catch (Exception e) {e.printStackTrace();}// 设置保留6位小数，否则GeometryJSON默认保留4位小数GeometryJSON geometryJson = new GeometryJSON(7);return geometryJson.toString(geometry);}@Overridepublic String getResult(ResultSet rs, int columnIndex) throws SQLException {return null;}@Overridepublic String getResult(CallableStatement cs, int columnIndex) throws SQLException {return null;}
}

@Component
public class SpringContextUtil implements ApplicationContextAware {private static ApplicationContext applicationContext;@Overridepublic void setApplicationContext(ApplicationContext applicationContext) throws BeansException {SpringContextUtil.applicationContext = applicationContext;}//获取applicationContextpublic static ApplicationContext getApplicationContext() {return applicationContext;}//通过name获取 Bean.public static Object getBean(String name) {return getApplicationContext().getBean(name);}//通过class获取Bean.public static <T> T getBean(Class<T> clazz) {return getApplicationContext().getBean(clazz);}//通过name,以及Clazz返回指定的Beanpublic static <T> T getBean(String name, Class<T> clazz) {return getApplicationContext().getBean(name, clazz);}//关闭springbootpublic static void close(){((ConfigurableApplicationContext)(getApplicationContext())).close();}//得到当前线程的HttpServletResponse,可在静态方法中得到public static HttpServletResponse getHttpServletResponse(){return ((ServletRequestAttributes) RequestContextHolder.currentRequestAttributes()).getResponse();}//得到当前线程的HttpServletRequest,可在静态方法中得到public static HttpServletRequest getHttpServletRequest(){return ((ServletRequestAttributes) RequestContextHolder.currentRequestAttributes()).getRequest();}}

@Repository
public interface CommonCodeMapper extends BaseMapper<CommonCode> {/*** EWKB是pg数据库自定义的类型，所以需要用数据库函数* @param geoJson* @return*/@Select("select ST_GeomFromGeoJSON(#{geoJson})")String geo2EWKB(String geoJson);}

=============================mybatis中使用================================

在mapper类中使用示例：https://www.jianshu.com/p/6465189984b0

/*** 使用ResultMap */
@Results(id = "userMap", value = {//可以使用这种方式来处理字段名和数据库表字段名不一致的情况@Result(column = "username", property = "username", jdbcType=JdbcType.VARCHAR,typeHandler = WKB2GeoJsonTypeHandler.class),@Result(column = "passwd", property = "passwd", jdbcType=JdbcType.VARCHAR),@Result(column = "birth_day", property = "birthDay", jdbcType=JdbcType.VARCHAR)})
@Select("SELECT * FROM t_user WHERE id=#{id}")
User loadByIdResultMap(Long id);/*** 引用其他的Result */
@ResultMap("userMap")
@Select("SELECT * FROM t_user WHERE id=#{id}")
User loadByIdResultMapReference(Long id);

在xml中使用示例示例：

    <resultMap id="locationResultMap" type="com.zjzy.model.po.ExaminationApplication"><result typeHandler="com.zjzy.mapper.typehandler.WKB2GeoJsonTypeHandler" column="dig_position" javaType="String"property="digPosition"/></resultMap><select id="selectExaminationApplicationByPage" resultMap="locationResultMap"></select>

注意：

1.postgresql的JDBC实现中（驱动），数据自定义的类型对应java类型一般都通过实现

org.postgresql.util.PGobject。

2.对应数据库geometry类型的java类不在PG的JDBC驱动的实现类中，因为geometry类型在PG的扩展postgis中，所以响应的要引入postGIS这部分的驱动，

3. PG的JDBC驱动底层也是通过SOCKET连接org.postgresql.core.PGStream#createSocket

4.原生jdbc接口在java.sql包中。

5.一定要实现org.postgresql.util.PGobject#getValue方法因为，org.postgresql.jdbc.PgPreparedStatement#setPGobject底层调用org.postgresql.jdbc.PgPreparedStatement#setString(int, java.lang.String, int)时

要用到org.postgresql.util.PGobject#getValue方法

==============================2022.12.12============================

以下方式不用导入 net.postgis包

package com.zjzy.mapper.typehandler;import com.alibaba.fastjson.JSONObject;
import com.zjzy.util.GisUtil;
import com.zjzy.util.SpringContextUtil;
import lombok.extern.slf4j.Slf4j;
import org.apache.ibatis.type.JdbcType;
import org.apache.ibatis.type.TypeHandler;
import org.geotools.geojson.geom.GeometryJSON;
import org.geotools.geometry.jts.JTS;
import org.geotools.geometry.jts.WKBReader;
import org.geotools.referencing.CRS;
import org.locationtech.jts.geom.Geometry;
import org.locationtech.jts.io.ByteOrderValues;
import org.locationtech.jts.io.ParseException;
import org.locationtech.jts.io.WKBWriter;
import org.locationtech.jts.io.WKTWriter;
import org.opengis.referencing.crs.CoordinateReferenceSystem;
import org.opengis.referencing.operation.MathTransform;
import org.postgis.PGbox2d;
import org.postgis.PGgeometry;
import org.postgresql.util.PGobject;
import org.springframework.core.env.Environment;import java.io.IOException;
import java.sql.CallableStatement;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;/*** @version 1.0* @description* @Author yaoct* @create 2021/12/22 16:19*/
@Slf4j
public class WKB2GeoJsonTypeHandler implements TypeHandler<String> {/*** 插入数据，转换,geoJson2EWKB* @param ps* @param i* @param parameter* @param jdbcType* @throws SQLException*/@Overridepublic void setParameter(PreparedStatement ps, int i, String parameter, JdbcType jdbcType) throws SQLException {//EWKB是pg数据库自定义的类型，所以需要用数据库函数,插入数据库一般次数较少，这样并不会对数据库造成过大负担
//        CommonCodeMapper mapper = SpringContextUtil.getBean(CommonCodeMapper.class);
//        String EWKB = mapper.geo2EWKB(parameter);
//        PGgeometry ewkb = new PGgeometry(EWKB);
//        ps.setObject(i,ewkb);//通过geoTool转换WKBGeometryJSON geometryJson = new GeometryJSON(7);Geometry geometry = null;try {geometry = geometryJson.read(parameter);} catch (IOException e) {e.printStackTrace();}
//        System.out.println(read.toString());geometry.setSRID(4326);
//        GeometryJSON geometryJson = new GeometryJSON(7);//方式1.基于net.postgis
//        WKBWriter wkbWriter = new WKBWriter(2, ByteOrderValues.BIG_ENDIAN,true);
//        byte[] write = wkbWriter.write(geometry);
//        String s1 = WKBWriter.toHex(write);
//        PGgeometry ewkb = new PGgeometry(s1);//EWKB比WKB多了SRID头字符串，PGgeometry.toString()会自动添加SRID
//        ps.setObject(i,ewkb);//方式2.设置ewkb,Postgresql驱动会先去数据库 pg_catalog.pg_type 查出geometry的类型id，这里的geometry字符串对应数据库pg_catalog.pg_type表中的geometry//以下方式不用导入net.postgis包
//        PGobject pGobject = new PGobject();
//        pGobject.setType("geometry");
//        pGobject.setValue(s1);
//        ps.setObject(i,pGobject);//方式3.设置拼接ewkt//以下方式不用导入net.postgis包，ewkb太长会超出sql限制，以下转换为ewktPGobject pGobject = new PGobject();pGobject.setType("geometry");String pre="SRID="+4326+";";pGobject.setValue(pre+GisUtil.Geometry2WKT(geometry));ps.setObject(i,pGobject);}/*** 取出数据转换,WKB->Geojson* @param rs* @param columnName* @return* @throws SQLException*/@Overridepublic String getResult(ResultSet rs, String columnName) throws SQLException {String WKB = rs.getString(columnName);if(WKB==null){return null;}WKBReader reader = new WKBReader( );Geometry geometry = null;try {geometry = reader.read(WKBReader.hexToBytes(WKB));} catch (ParseException e) {//转换失败return null;}//转换成4326try {int srid = geometry.getSRID();if(srid==0)srid=4549;//默认4549int targetSrid=4326;//默认4326Environment environment = SpringContextUtil.getBean(Environment.class);if(environment!=null){String sridTarget = environment.getProperty("sridTarget");if(sridTarget!=null){try {targetSrid=Integer.valueOf(sridTarget);} catch (Exception e){//转换失败}}}CoordinateReferenceSystem sourceCRS = CRS.decode("EPSG:"+srid,true);CoordinateReferenceSystem targetCRS = CRS.decode("EPSG:"+targetSrid,true);MathTransform transform = CRS.findMathTransform(sourceCRS, targetCRS,true);geometry = JTS.transform(geometry, transform);} catch (Exception e) {e.printStackTrace();}// 设置保留6位小数，否则GeometryJSON默认保留4位小数GeometryJSON geometryJson = new GeometryJSON(7);String json = geometryJson.toString(geometry);JSONObject jsonObject = JSONObject.parseObject(json);jsonObject.put("srid",geometry.getSRID());return jsonObject.toJSONString();}@Overridepublic String getResult(ResultSet rs, int columnIndex) throws SQLException {return null;}@Overridepublic String getResult(CallableStatement cs, int columnIndex) throws SQLException {return null;}}

package com.zjzy.util;import org.geotools.geojson.geom.GeometryJSON;
import org.geotools.geometry.jts.JTS;
import org.geotools.geometry.jts.WKBReader;
import org.geotools.referencing.CRS;
import org.geotools.referencing.GeodeticCalculator;
import org.geotools.referencing.crs.DefaultGeographicCRS;
import org.locationtech.jts.geom.Geometry;
import org.locationtech.jts.io.*;
import org.opengis.referencing.FactoryException;
import org.opengis.referencing.crs.CoordinateReferenceSystem;
import org.opengis.referencing.operation.MathTransform;
import org.opengis.referencing.operation.TransformException;import java.io.IOException;/*** @Author yaoct* @Date 2022/9/16 10:55* @Version 1.0* @description*/
public class GisUtil {/*** WKB字符串转Geometry格式* @param WKB* @return*/public static Geometry WKB2Geometry(String WKB){WKBReader reader = new WKBReader();Geometry geometry = null;try {geometry = reader.read(WKBReader.hexToBytes(WKB));} catch (ParseException e) {//转换失败throw new RuntimeException("转换失败",e);}return geometry;}/*** Geometry格式转WKB字符串* @param geometry* @return*/public static String Geometry2WKB(Geometry geometry){WKBWriter wkbWriter = new WKBWriter(2, ByteOrderValues.BIG_ENDIAN,true);byte[] write = wkbWriter.write(geometry);String ret = WKBWriter.toHex(write);return ret;}/*** WKT字符串转Geometry格式* @param WKT* @return*/public static Geometry WKT2Geometry(String WKT){WKTReader reader = new WKTReader();Geometry geometry = null;try {geometry = reader.read(WKT);} catch (ParseException e) {//转换失败throw new RuntimeException("转换失败",e);}return geometry;}/*** Geometry格式转WKT字符串* @param geometry* @return*/public static String Geometry2WKT(Geometry geometry){WKTWriter wktWriter = new WKTWriter();String wkt= wktWriter.write(geometry);return wkt;}/*** 转换Geometry坐标* @param geometry* @param targetSrid 新坐标* @return*/public static Geometry coordinateTransfer(Geometry geometry, int targetSrid){int originSrid = geometry.getSRID();CoordinateReferenceSystem sourceCRS = null;CoordinateReferenceSystem targetCRS = null;MathTransform transform=null;try {sourceCRS = CRS.decode("EPSG:"+originSrid,true);targetCRS = CRS.decode("EPSG:"+targetSrid,true);transform = CRS.findMathTransform(sourceCRS, targetCRS,true);} catch (FactoryException e) {throw new RuntimeException("坐标错误",e);}Geometry ret = null;try {ret = JTS.transform(geometry, transform);} catch (TransformException e) {throw new RuntimeException("坐标转换错误",e);}return ret;}/*** Geometry->geoJson* @param geometry* @return*/public static String geometry2GeoJson(Geometry geometry){// 设置保留6位小数，否则GeometryJSON默认保留4位小数GeometryJSON geometryJson = new GeometryJSON(7);String json = geometryJson.toString(geometry);
//        JSONObject jsonObject = JSONObject.parseObject(json);
//        jsonObject.put("srid",geometry.getSRID());
//        return jsonObject.toJSONString();return json;}/*** geoJson->Geometry* @param geoJson* @return*/public static Geometry geoJson2Geometry(String geoJson){GeometryJSON geometryJson = new GeometryJSON(7);Geometry ret=null;try {Geometry read = geometryJson.read(geoJson);} catch (IOException e) {throw new RuntimeException("转换失败",e);}return ret;}/*** 计算两点间的距离* @param lon1* @param lat1* @param lon2* @param lat2* @return*/public static double calculateDistance(double lon1,double lat1,double lon2,double lat2){//CoordinateReferenceSystem sourceCRS = CRS.decode("EPSG:"+srid,true);GeodeticCalculator geodeticCalculator = new GeodeticCalculator(DefaultGeographicCRS.WGS84);// 起点经纬度geodeticCalculator.setStartingGeographicPoint(lon1,lat1);// 末点经纬度geodeticCalculator.setDestinationGeographicPoint(lon2,lat2);// 计算距离，单位：米double distance = geodeticCalculator.getOrthodromicDistance();return distance;}
}

===================================================================

参考：

Mybatis-plus读取和保存Postgis geometry数据 - 简书

MyBatis Plus 自动类型转换之TypeHandler - 周世元ISO8859-1 - 博客园

GeoTools The Open Source Java GIS Toolkit — GeoTools

Geotools中Geometry对象与GeoJson的相互转换_mathyrs的博客-CSDN博客_geojson转geometry

mybatis 自定义TypeHandler映射Geometry空间几何数据 PGPoint (java +mybatis+ pgsql) - 灰信网（软件开发博客聚合）

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