Using JNI method in SWIG's input file

Sometimes we've to use JNI's built in methods in SWIG's input file. Though SWIG's proxy class can do everything possible for JNI,but I prefer to use JNI's method where SWIG gets complicated. For example, I have a byte Array in my java file.If I want to retrieve the array by pinning, we can use getArrayPrimitiveCritical(

) JNI method.Here I gonna give an example that will help you a lot about using JNI's built in method in SWIG.

Let the java file is Runner.java and the code is:


public class Runner {
static {
try {
System.loadLibrary("sample");
}
catch (UnsatisfiedLinkError e) {

System.err.println("Native code library failed to load.\n" + e);
System.exit(1);
}
}



public static void main(String argv[]) {
//declaration of the array
byte array[] = new byte [10000];
for (int i = 0; i <>
array[i] = (byte)((int)i%64);

//call the native method

sample.point_accessPinArray(array);
}
}


Now the input file can be like this(sample.i)

/* File : sample.i */

%module sample
%{
#include "ByteArray.h"
#include "/usr/lib/jvm/java-6-openjdk/include/jni.h"

JNIEXPORT void JNICALL Java_sampleJNI_point_1accessPinArray(JNIEnv *jenv, jclass jcls,jbyteArray array) {

int i;int size;
size = (*jenv)->GetArrayLength(jenv, array);
//pinning process is going to be started from here if your garbage collector supports //pinning.

jbyte* body = (*jenv)->GetPrimitiveArrayCritical(jenv, array, NULL);

(*jenv)->ReleasePrimitiveArrayCritical(jenv, array, body, 0);
}
%}
%native(point_accessPinArray) void *point_accessPinArray(jbyteArray array);



Commands to compile and run:

$swig -java sample.i
$gcc -c -fpic sample_wrap.cxx -I/usr/lib/jvm/java-6-openjdk/include/ -I/usr/lib/jvm/java-6-openjdk/include/linux/
$gcc -shared sample_wrap.o -o libexample.so
$export LD_LIBRARY_PATH=.:$LD_LIBRARY_PATH
$javac Runner.java
$java Runner