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-------------------- J P R O J . 4 --------------------
This is the second release of JNI wrappers for the main proj4 functions.
PLEASE read the following information.
The first release of JNI wrappers were created by:
http://www.hydrologis.com
For more information regarding the current release please see the web page at:
http://www.geoapi.org/geoapi-proj4/
---------------------------------------------------
What is "Proj.4 wrapper":
-------------
"Proj.4 wrapper" is a small library of Java classes that wrap a few Proj.4 functions by
using the Java Native Interface (JNI). The main Java class is org.proj4.PJ.
Compilation:
-------------
To compile the native part, configure has to be run in the proj directory like this:
CFLAGS=-Iinclude2 ./configure --with-jni=include1
where
include1 = folder in which the header file jni.h resides (usually $JAVA_HOME/include)
include2 = folder in which the header file jni_md.h resides (usually $JAVA_HOME/include/linux or whatever)
On MacOS, those two folders are /System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK/Home/include/
The java part is compiled by running ant inside the "jniwrap" folder.
This will compile the classes and archive them in a jar library.
It applies to Linux, Macos and Windows (and virtually to every system
supporting java).
Requirements:
-------------
Beyond the ones already put by Proj.4, you need:
- JSE 1.5+, the Java standard development kit version 1.5 or above
- Ant, to run the build
- Doxygen for the documentation generation
Documentation:
--------------
The documentation is held inside the code and can be retrieved by running
doxygen inside the folder jniwrap. This will create the HTML format
documentation inside of jniwrap/docs
The standard way to achieve this is to use an Ant target:
ant do_make_help
License:
--------
GPL for the first release
Proj.4 license for the second release.
Authors:
--------
Andrea Antonello (andrea.antonello@hydrologis.com)
Martin Desruisseaux (martin.desruisseaux@geomatys.fr)
Usage & a fast example:
-----------------------
The jproj.jar is all is needed to implement proj support in java applications.
The whole job is done by the proj4, so there are just a couple of functions that
be used.
The best way is to see everything through an example.
In the following example we create two Coordinate System and transform 3 points.
The Coordinate System and the points are hard-coded for simplicity. Of course,
real applications would read them from a file or other data source.
________________________________________________________________________________
import org.proj4.*;
import java.util.Arrays;
/**
* Converts coordinates from EPSG:32632 (WGS 84 / UTM zone 32N) to WGS84,
* then prints the result to the standard output stream.
*/
public class Main {
public static void main(String[] args) throws PJException {
PJ sourcePJ = new PJ("+init=epsg:32632"); // (x,y) axis order
PJ targetPJ = new PJ("+proj=latlong +datum=WGS84"); // (λ,φ) axis order
double[] coordinates = {
500000, 0, // First coordinate
400000, 100000, // Second coordinate
600000, -100000 // Third coordinate
};
sourcePJ.transform(targetPJ, 2, coordinates, 0, 3);
System.out.println(Arrays.toString(coordinates));
}
}
________________________________________________________________________________
compile the Main code:
we assume that proj was compiled with the right flag to support jproj.
Therefore we have a library called jproj.jar.
Thus we compile the Main.java with the command:
javac -classpath <path to the jar library>/jproj.jar Main.java
and execute the created test case with:
java -cp .:<path to the jar library>/jproj.jar -Djava.library.path=<path to the libproj, if needed> Main
That's it, enjoy!
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