我在MySQL中有一列WKT POLYGON值(我继承了db)。在Google地图上查询和渲染多边形。由于Google地图多边形叠加需要一个点数组,因此前一个用户将WKT值转换为坐标对并将它们存储在另一列中。这实际上运作得相当好,但还不够好。
首先,转换偶尔会出现问题,而且有两个问题,我正在寻找方法来加快转换速度。
重新。第一个问题,我必须重新实现这个,我正在寻找一个转换器,将WKT多边形转换为一串坐标。我想我可以使用它来编写一个存储过程来查询WKT列并吐出一串JSON文本,这些文本可以很容易地转换为Google Maps多边形,甚至可以预处理所有WKT多边形并将它们存储为文本像它已经完成了,但这次是正确的值。
所以,我真的在寻找一个函数来将WKT转换为其组成点坐标的字符串,有点像这样
SELECT AsStringOfCoords(WKT_Column) FROM table WHERE condition
AsStringOfCoords()
将成为我的自定义函数。
答案 0 :(得分:0)
我写了一个小的C ++程序来为KML多边形做MySQL WKT多边形。 这件事情如下:
源代码在这里......
#include <iostream>
#include <string>
/*
* Database includes...
*/
#include <mysql_connection.h>
#include <cppconn/driver.h>
#include <cppconn/exception.h>
#include <cppconn/resultset.h>
#include <cppconn/statement.h>
#include <cppconn/prepared_statement.h>
#include "../iolib/IOCoreFuncs.h"
#include "../iolib/ioconfigurador.h"
using namespace std;
using namespace sql;
using namespace IOCore;
sql::Connection * conectaDB(string dbSvr, string dbUsr, string dbPwd, string dbNombre);
int main(int argc, char **argv) {
string qry, arproc;
Connection * dbCon;
Statement * stmt;
IOConfigurador * miConf;
ResultSet * rs;
//Cargar configuración...
if (argc == 3) {
arproc = argv[2];
} else {
cout << "Using mode: sqltokml <polygon id> <file kml to export>\n";
return 1;
}
dbCon = conectaDB("dbserver", "dbuser"), "dbpasswd", "dbname");
stmt = dbCon->createStatement();
qry = "SELECT name, astext(geoarea) from " + "table name" + " where id = '" + argv[1] + "';";
rs = stmt->executeQuery(qry);
if (rs->rowsCount() > 0) {
string polnombre, polcoords;
string salida;
while (rs->next()) {
ofstream sale;
polnombre = rs->getString(1);
polcoords = rs->getString(2);
salida = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
"<kml xmlns=\"http://www.opengis.net/kml/2.2\" xmlns:gx=\"http://www.google.com/kml/ext/2.2\" xmlns:kml=\"http://www.opengis.net/kml/2.2\" xmlns:atom=\"http://www.w3.org/2005/Atom\">\n"
"<Document>\n"
"<name>" + polnombre + ".kml</name>\n"
"<Style id=\"sh_ylw-pushpin3\">\n"
"<IconStyle>\n"
"<scale>1.3</scale>\n"
"<Icon>\n"
"<href>http://maps.google.com/mapfiles/kml/pushpin/ylw-pushpin.png</href>\n"
"</Icon>\n"
"<hotSpot x=\"20\" y=\"2\" xunits=\"pixels\" yunits=\"pixels\"/>\n"
"</IconStyle>\n"
"<LineStyle>\n"
"<color>467f5500</color>\n"
"<width>3</width>\n"
"</LineStyle>\n"
"<PolyStyle>\n"
"<color>46ff5555</color>\n"
"</PolyStyle>\n"
"</Style>\n"
"<StyleMap id=\"msn_ylw-pushpin10\">\n"
"<Pair>\n"
"<key>normal</key>\n"
"<styleUrl>#sn_ylw-pushpin30</styleUrl>\n"
"</Pair>\n"
"<Pair>\n"
"<key>highlight</key>\n"
"<styleUrl>#sh_ylw-pushpin3</styleUrl>\n"
"</Pair>\n"
"</StyleMap>\n"
"<Style id=\"sn_ylw-pushpin30\">\n"
"<IconStyle>\n"
"<scale>1.1</scale>\n"
"<Icon>\n"
"<href>http://maps.google.com/mapfiles/kml/pushpin/ylw-pushpin.png</href>\n"
"</Icon>\n"
"<hotSpot x=\"20\" y=\"2\" xunits=\"pixels\" yunits=\"pixels\"/>\n"
"</IconStyle>\n"
"<LineStyle>\n"
"<color>467f5500</color>\n"
"<width>3</width>\n"
"</LineStyle>\n"
"<PolyStyle>\n"
"<color>46ff5555</color>\n"
"</PolyStyle>\n"
"</Style>\n"
"<Folder>\n"
"<name>" + polnombre + "</name>\n"
"<Placemark>\n"
"<name>" + polnombre + "</name>\n"
"<styleUrl>#msn_ylw-pushpin10</styleUrl>\n"
"<Polygon>\n"
"<tessellate>1</tessellate>\n"
"<outerBoundaryIs>\n"
"<LinearRing>\n"
"<coordinates>\n";
//Coordinates tranformation...
polcoords = polcoords.substr(9, polcoords.size() - 11);
vector< string > lascoords = split(polcoords, ",");
for (unsigned i = 0; i < lascoords.size(); i++) {
salida += lascoords[i].substr(0, lascoords[i].find(" ")) + ",";
salida += lascoords[i].substr(lascoords[i].find(" ") + 1) + ",0 ";
}
salida += "\n</coordinates>\n"
"</LinearRing>\n"
"</outerBoundaryIs>\n"
"</Polygon>\n"
"</Placemark>\n"
"</Folder>\n"
"</Document>\n"
"</kml>";
sale.open(arproc.c_str(), ios::out | ios::app);
sale << salida ;
sale.close();
}
}
rs->close();
stmt->close();
dbCon->close();
}
sql::Connection * conectaDB(string dbSvr, string dbUsr, string dbPwd, string dbNombre)
{
sql::Connection * retval;
sql::Driver *ctrl;
try {
ctrl = get_driver_instance();
retval = ctrl->connect(dbSvr, dbUsr, dbPwd);
retval->setSchema(dbNombre);
} catch (sql::SQLException &err) {
cout<<"Errors... :( "<<err.what()<<"\ngoing out\n";
retval = 0;
}
return retval;
}
我希望这可以帮到你。很容易将其转换为MySQL存储过程,或者在PHP或其他语言中使用它...我也有一些php / javascript脚本用点做同样的事情。