使用GDALOGR *** 作Postgresql数据库

概述 GDAL(Geospatial Data AbstractionLibrary)是一个在X/MIT许可协议下的开源栅格空间数据转换库。它利用抽象数据模型来表达所支持的各种文件格式。它还有一系列命令行工具来进行数据转换和处理。 本文将使用GDAL/OGR库读写Postgresql数据库中的表，代码执行环境在ubuntu12.04， 直接上代码 #include "/usr/include/gd 

GDAL(Geospatial Data Abstractionlibrary)是一个在X/MIT许可协议下的开源栅格空间数据转换库。它利用抽象数据模型来表达所支持的各种文件格式。它还有一系列命令行工具来进行数据转换和处理。

本文将使用GDAL/OGR库读写Postgresql数据库中的表，代码执行环境在ubuntu12.04，

直接上代码

#include "/usr/include/gdal/ogrsf_frmts.h"#include "/usr/include/gdal/ogr_feature.h"#include "/usr/include/gdal/ogr_geometry.h"#include "/usr/include/gdal/gdal_priv.h"	/////////////////////////////////使用OGR读Postgresql///////////////////////////////int getFeature( vector<RoadRec>& RoadList //RoadRec是自定义数据结构 ){	OGRRegisterall();	const char* filepath =	"PG:dbname=test host=172.0.0.1 port=5432 user=postgres password=postgres";	const char* drivename = "Postgresql"; //标明是Postgresql数据库 *** 作	const char* ptablename = "roadList";//数据表名称 table name	OGRSfdriver* pdriver = NulL;	OGRLayer* player = NulL;	OGrdataSource* pDS = NulL;    //注册驱动，这样ogr就知道即将打开的是什么类型的文件	pdriver = OGRSfdriverRegistrar::GetRegistrar()->GetDriverByname(drivename);	if ( pdriver == NulL ) {		return FAILURE;	}    //驱动注册完毕打开数据库	pDS = pdriver->Open(filepath,0);	if ( NulL == pDS ) {		return FAILURE;	}    //打开数据库中的数据表	player = pDS->GetLayerByname(ptablename);	if ( NulL == player ) {		return FAILURE;	}	//OGRFeature*相当于指向数据表中一条记录的指针，根据它可以获取每一个字段	OGRFeature* pogrfeature = NulL;	player->resetReading();	int gID = 0;    //循环遍历每一条记录，这里的遍历是按照表中数据的存储顺序遍历    //并不会按照主键唯一值顺序遍历，这和sql的select结果的顺序不一样    //想要一样应该创建索引，并将表数据按索引顺序存储/*CREATE INDEX roadList_gID_IDx  ON roadList  USING btree  (gID);cluster  roadList using roadList_gID_IDx;*/	while( (pogrfeature = player->GetNextFeature()) != NulL )	{	    gID++;		//获取一条记录中的几何属性字段的引用		OGRGeometry *pgeo = pogrfeature->GetGeometryRef();		if ( NulL != pgeo )		{			//判断一下是不是自己想要的类型，这里我的数据是道路，line数据		    if ( wkbMultilinestring == pgeo->getGeometryType() || wkblinestring == pgeo->getGeometryType() )		    {		        OGRGeometry* pgeometry = pgeo;				//单独处理一下multilinestring的情况		        if ( wkbMultilinestring == pgeo->getGeometryType() )		        {		            OGRMultilinestring* pmultilinestring = (OGRMultilinestring*)pgeo;                    if( 1 != pmultilinestring->getNumGeometrIEs() )                    {                        return FAILURE;                    }                    pgeometry = pmultilinestring->getGeometryRef(0);		        }				//定义OGRlinestring类型指针指向几何数据				//这样就可以使用OGRlinestring提供的函数接口了                OGRlinestring* pline = (OGRlinestring *)pgeometry;                int pointnum = pline->getNumPoints();                RoadRec tmp;//自定义数据类型				//使用OGRFeature类提供的 GetFIEldAsInteger//方法获取每个字段的值，”link_ID”,”road_name”都是字段名				                tmp.link_ID = pogrfeature->GetFIEldAsInteger("link_ID");                //tmp.src_ID = pogrfeature->GetFIEldAsInteger("src_ID");                tmp.road_name = pogrfeature->GetFIEldAsstring("road_name");                tmp.one_way = pogrfeature->GetFIEldAsInteger("one_way");				//获得几何属性的每一个点坐标信息                for ( int pointID = 0; pointID < pointnum;++pointID )                {                    OGRPoint point;                    pline->getPoint(pointID,&point);                    GEO_POINT geo_point;                    geo_point.x = point.getX();                    geo_point.y = point.getY();                    tmp.vstShpList.push_back(geo_point);                }                RoadList.push_back(tmp);		    }		}		//释放Feature资源        OGRFeature::DestroyFeature(pogrfeature);        //cout<<link_ID<<endl;	}    //释放指向该数据库的指针OGrdataSource::DestroyDataSource(pDS);	return SUCCESS;}/////////////////////////////////使用OGR写Postgresql///////////////////////////////int setFeature( const vector<RoadRec>& RoadList ){    OGRRegisterall();	const char* filepath =	"PG:dbname=test host=172.0.0.1 port=5432 user=postgres password=postgres";	const char* drivename = "Postgresql";	const char* ptablename = "roadList";	OGRSfdriver* pdriver = NulL;	OGRLayer* player = NulL;	OGrdataSource* pDS = NulL;	pdriver = OGRSfdriverRegistrar::GetRegistrar()->GetDriverByname(drivename);	if ( pdriver == NulL ) {		return FAILURE;	}	pDS = pdriver->Open(filepath,0);	if ( NulL == pDS ) {		return FAILURE;	}    //相当于SQL语句中的创建数据表，只是这里只先指定表名称和几何字段属性    player = pDS->CreateLayer( ptablename,NulL,wkblinestring,NulL );    if ( NulL == player )    {            return FAILURE;    }    //定义一个字段one_way    OGRFIEldDefn* pfIElddefn_oneway = new OGRFIEldDefn("one_way",OFTInteger);    //在数据表中创建定义的字段    player->CreateFIEld(pfIElddefn_oneway);    OGRFIEldDefn* pfIElddefn_name = new OGRFIEldDefn("road_name",OFTString);    player->CreateFIEld(pfIElddefn_name);    //删除字段定义指针    delete pfIElddefn_oneway;    delete pfIElddefn_name;    int roadnum = RoadList.size();    //循环写入每一条道路数据    for ( int roadcnt = 0; roadcnt < roadnum ;++roadcnt )    {            const RoadRec& roadrec = RoadList.at(roadcnt);            OGRlinestring* pline = new OGRlinestring;//要写入的几何字段            int pointnum = roadrec.vstShpList.size();            for ( int pointcnt = 0; pointcnt < pointnum ;++pointcnt )            {                    const GEO_POINT& point = roadrec.vstShpList.at(pointcnt);                    pline->addPoint(point.x,point.y);            }            OGRGeometry* pgeo = (OGRGeometry*)pline;            pgeo->setCoordinateDimension(2);//设置坐标系维度            //创建一个指向要写入的记录的指针//指定要写入的数据库player->GetLayerDefn()            OGRFeature* pfeature = OGRFeature::CreateFeature( player->GetLayerDefn() );			//设置当前记录的字段值            pfeature->SetFIEld("one_way",roadrec.one_way);            pfeature->SetFIEld("road_name",roadrec.road_name.c_str());            if ( OGRERR_NONE != pfeature->SetGeometry( pgeo ) )            {                    return FAILURE;            }			//将记录写入数据表            if ( OGRERR_NONE != player->CreateFeature( pfeature ) )            {                    return FAILURE;            }            delete pline;            OGRFeature::DestroyFeature(pfeature);    }    OGrdataSource::DestroyDataSource(pDS);	return SUCCESS;}int main(){	vector<RoadRec> roadList;	getFeature(roadList);	cout<<roadList.size()<<endl;    setFeature(roadList);	return 0;}

编译链接：g++ -o feature feature_pro.cpp -lgdal

总结

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