code in blog.sheimi.me: 2012-09-05-a-summary-of-using-jni (1)

CVJNI.java

// CVJNI.java
import java.io.*;

public class CVJNI {
  //Load jni library
  static {
    try {
      System.loadLibrary("cvjni");
    } catch (Exception e) {
      e.printStackTrace();
    }
  }

  //native method
  public static native byte[] toBMP(byte[] imageSource);

  //main
  public static void main(String [] args) {
    String input = args[0];
    String output = args[1];

    FileInputStream fi = null;
    FileOutputStream fo = null;

    try {
      File infile = new File(args[0]);
      int len = (int)infile.length();
      //get source
      fi = new FileInputStream(infile);
      byte[] imageSource = new byte[len];
      fi.read(imageSource, 0, len);
      //revoke native method
      byte[] outImage = CVJNI.toBMP(imageSource);
      //write
      fo = new FileOutputStream(output);
      fo.write(outImage);
    } catch(IOException e) {
      e.printStackTrace();
    } finally {
      try {
        if (fi != null)
          fi.close();
        if (fo != null)
          fo.close();
      } catch(IOException e) {
        e.printStackTrace();
      }
    }
  }
}