Question

I am trying to use a package in my final year project called libfprint. This is an opensource fingerprint reader SDK. I am doing my project in Java so I need to port over the libfprint functionality.

A stroke of good luck hit me and turned out somebody already did this. A package called jlibfprint is a JNI wrapper for libfprint.

So I followed the instructions in both jlibfprint and libfprint for setup. libfprint more or less works fine. As for jlibfprint, when I tried to run the sample program I got,

Exception in thread "main" java.lang.UnsatisfiedLinkError: no JlibFprint_jni in java.library.path
    at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1681)
    at java.lang.Runtime.loadLibrary0(Runtime.java:840)
    at java.lang.System.loadLibrary(System.java:1047)
    at JlibFprint.<clinit>(JlibFprint.java:28)
    at SampleRun.main(SampleRun.java:30)

JlibFprint.(JlibFprint.java:28)

is referring to

 static {
    System.loadLibrary("JlibFprint_jni");
 }

So now I’m looking through the project properties and get to the field “Native library location”, and I point it to the directory containing a single file called libJlibFprint_jni.so.

Now when I run the program, the error I get is,

Exception in thread "main" java.lang.UnsatisfiedLinkError: JlibFprint.enroll_finger()LJlibFprint$fp_print_data;
    at JlibFprint.enroll_finger(Native Method)
    at SampleRun.main(SampleRun.java:36)
Enroll the first finger...

Here are the sample Java file

SampleRun.java

public class SampleRun {
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        JlibFprint jlibfprint = new JlibFprint();
        JlibFprint.fp_print_data pd1, pd2;
        int matchValue;
        try
        {
            System.out.println("Enroll the first finger...");
            pd1 = jlibfprint.enroll_finger();
            System.out.println("Compare the previous acquisition with the next one...");
            pd2 = jlibfprint.enroll_finger();
            matchValue = JlibFprint.img_compare_print_data(pd1, pd2);

            System.out.println(matchValue);
            if (matchValue > JlibFprint.BOZORTH_THRESHOLD)
            {
                System.out.println("[OK] The two fingerprints are compatible!");
            }
            else
            {
                System.out.println("[FAIL] The two fingerprints are not compatible!");
            }
        }
        catch (JlibFprint.EnrollException e)
        {
            System.err.format("Enroll Exception [%d]\n", e.enroll_exception);
            e.printStackTrace();
        }
    }
}

I am using Ubuntu 11.10 with Eclipse Juno.

Anybody with a breeze of knowledge in this area would be a great help !

Answer 1

Just found the solution here. I’m sure it was obvious to some but JNI is totally new to me. The solution was:

“Create a new file in /etc/ld.so.conf.d/ called .conf

Edit the file and add a line per directory of shared libraries (*.so
files), it will look something like:

/usr/lib/APPLICATION/lib Reload the list of system-wide library paths:
sudo ldconfig”