How to convert HEXEWKB to Latitude, Longitude (in

Question

I downloaded Street information from the Open Street Map project. This file is basically a CSV with the following fields:

CSV fields
==============================================
1 : id; UniqueId of the street(always null for the moment)
2 : name; The name 
3 : location; The middle point of the street in HEXEWKB
4 : length ; Length of the street in meters
5 : countrycode; The iso3166 Alpha2 Code of the country 
6 : gid ; GlobalId (not use yet)
7 : type; The type of street (see bellow)
8 : oneway; Whether the street is a one way street
9 : shape; The delimitation of the street in HEXEWKB 

I cannot find how to covert this HEXEWKB field to something useful for me, like Latitude, Longitude. Can anyone give me some pointers on how this format works (or better, point me to some java lib that does that job for me)?

Example rows from the CSV:

3343954 Blijde Inkomststraat    0101000020E6100000AECB9307F9D812400F2ADCE003704940  454.419285782969    NL      tertiary    t0102000020E610000007000000CD4301367BDB1240B59377C4D76F49402E7A02BC60DB12404F80176CD96F494061C8451042DB1240F5B814FCDB6F49405104279133DB12402AE0432EDD6F4940875C5FDA26DB12409434DA05DE6F494018DEF64E16D81240FCA2A9431370494049B258D471D61240839A6BE22E704940
3343967 Dagobertstraat  0101000020E6100000E40AAE6CD6DA1240941F95531C704940  216.34491093149 NL      residential f   0102000020E610000004000000F15C29159ED9124094FF2499307049406EDDCD531DDA1240C8E99040287049400CC2267C00DC12409672631F097049403A5739590FDC12400EA9FD3108704940
3343968 Bogaardenstraat 0101000020E6100000C0D7C68E7CD81240F550364044704940  125.953915569017    NL      residential f   0102000020E610000002000000224D614AC9D7124048B19245507049405F622CD32FD91240A2F0D93A38704940

Answer 1

You can do that with JTS. It's easy to load the geometry from its EWKB Hexadecimal representation, using WBKReader.

import com.vividsolutions.jts.geom.Geometry;
import com.vividsolutions.jts.geom.GeometryFactory;
import com.vividsolutions.jts.geom.PrecisionModel;
import com.vividsolutions.jts.io.WKBReader;

import java.util.Arrays;
import java.util.List;

public class Foo {
    public static void main(String... args) throws Exception {
        final List<String> points = Arrays.asList(
                "0101000020E6100000AECB9307F9D812400F2ADCE003704940",
                "0101000020E6100000E40AAE6CD6DA1240941F95531C704940",
                "0101000020E6100000C0D7C68E7CD81240F550364044704940"
        );
        final GeometryFactory gm = new GeometryFactory(new PrecisionModel(), 4326);
        final WKBReader wkbr = new WKBReader(gm);
        for (String point: points) {
            byte[] wkbBytes = wkbr.hexToBytes(point);
            final Geometry geom = wkbr.read(wkbBytes);
            System.out.printf("%s -> %s\n", point, geom.toText());
            // you can access longitude and latitude via
            double longitude = geom.getCoordinate().x;
            double latitude = geom.getCoordinate().y;
            // then do what you need to do with it
        }
    }
}

Will print:

0101000020E6100000AECB9307F9D812400F2ADCE003704940 -> POINT (4.7118874725301065 50.87511835813722)
0101000020E6100000E40AAE6CD6DA1240941F95531C704940 -> POINT (4.713708589670862 50.875864455999505)
0101000020E6100000C0D7C68E7CD81240F550364044704940 -> POINT (4.71141265 50.87708285)

You may also know that JTS is on maven central, so it's easy to add a dependency to your project.

<dependency>
    <groupId>com.vividsolutions</groupId>
    <artifactId>jts</artifactId>
    <version>1.13</version> <!-- or RELEASE as stated in @RobAu comment below -->
</dependency>

As for the magic number 4326 is a common SRID for geographic coordinates which is the longitude/latitude on the WGS84 spheroid.

You can read this link and that one about that number, and a nice introduction to all that stuff.