2014-11-27 20:39:05 +08:00
|
|
|
Using OpenCV Java with Eclipse {#tutorial_java_eclipse}
|
|
|
|
==============================
|
|
|
|
|
|
|
|
Since version 2.4.4 [OpenCV supports Java](http://opencv.org/opencv-java-api.html). In this tutorial
|
|
|
|
I will explain how to setup development environment for using OpenCV Java with Eclipse in
|
|
|
|
**Windows**, so you can enjoy the benefits of garbage collected, very refactorable (rename variable,
|
|
|
|
extract method and whatnot) modern language that enables you to write code with less effort and make
|
|
|
|
less mistakes. Here we go.
|
|
|
|
|
|
|
|
Configuring Eclipse
|
|
|
|
-------------------
|
|
|
|
|
|
|
|
First, obtain a fresh release of OpenCV [from download page](http://opencv.org/downloads.html) and
|
2014-11-28 00:54:13 +08:00
|
|
|
extract it under a simple location like `C:\OpenCV-2.4.6\`. I am using version 2.4.6, but the steps
|
2014-11-27 20:39:05 +08:00
|
|
|
are more or less the same for other versions.
|
|
|
|
|
|
|
|
Now, we will define OpenCV as a user library in Eclipse, so we can reuse the configuration for any
|
|
|
|
project. Launch Eclipse and select Window --\> Preferences from the menu.
|
|
|
|
|
2014-11-28 21:21:28 +08:00
|
|
|
![](images/1-window-preferences.png)
|
2014-11-27 20:39:05 +08:00
|
|
|
|
|
|
|
Navigate under Java --\> Build Path --\> User Libraries and click New....
|
|
|
|
|
2014-11-28 21:21:28 +08:00
|
|
|
![](images/2-user-library-new.png)
|
2014-11-27 20:39:05 +08:00
|
|
|
|
|
|
|
Enter a name, e.g. OpenCV-2.4.6, for your new library.
|
|
|
|
|
2014-11-28 21:21:28 +08:00
|
|
|
![](images/3-library-name.png)
|
2014-11-27 20:39:05 +08:00
|
|
|
|
|
|
|
Now select your new user library and click Add External JARs....
|
|
|
|
|
2014-11-28 21:21:28 +08:00
|
|
|
![](images/4-add-external-jars.png)
|
2014-11-27 20:39:05 +08:00
|
|
|
|
2014-11-28 00:54:13 +08:00
|
|
|
Browse through `C:\OpenCV-2.4.6\build\java\` and select opencv-246.jar. After adding the jar,
|
2014-11-27 20:39:05 +08:00
|
|
|
extend the opencv-246.jar and select Native library location and press Edit....
|
|
|
|
|
2014-11-28 21:21:28 +08:00
|
|
|
![](images/5-native-library.png)
|
2014-11-27 20:39:05 +08:00
|
|
|
|
2014-11-28 00:54:13 +08:00
|
|
|
Select External Folder... and browse to select the folder `C:\OpenCV-2.4.6\build\java\x64`. If you
|
2014-11-27 20:39:05 +08:00
|
|
|
have a 32-bit system you need to select the x86 folder instead of x64.
|
|
|
|
|
2014-11-28 21:21:28 +08:00
|
|
|
![](images/6-external-folder.png)
|
2014-11-27 20:39:05 +08:00
|
|
|
|
|
|
|
Your user library configuration should look like this:
|
|
|
|
|
2014-11-28 21:21:28 +08:00
|
|
|
![](images/7-user-library-final.png)
|
2014-11-27 20:39:05 +08:00
|
|
|
|
|
|
|
Testing the configuration on a new Java project
|
|
|
|
-----------------------------------------------
|
|
|
|
|
|
|
|
Now start creating a new Java project.
|
|
|
|
|
2014-11-28 21:21:28 +08:00
|
|
|
![](images/7_5-new-java-project.png)
|
2014-11-27 20:39:05 +08:00
|
|
|
|
|
|
|
On the Java Settings step, under Libraries tab, select Add Library... and select OpenCV-2.4.6, then
|
|
|
|
click Finish.
|
|
|
|
|
2014-11-28 21:21:28 +08:00
|
|
|
![](images/8-add-library.png)
|
2014-11-27 20:39:05 +08:00
|
|
|
|
2014-11-28 21:21:28 +08:00
|
|
|
![](images/9-select-user-lib.png)
|
2014-11-27 20:39:05 +08:00
|
|
|
|
|
|
|
Libraries should look like this:
|
|
|
|
|
2014-11-28 21:21:28 +08:00
|
|
|
![](images/10-new-project-created.png)
|
2014-11-27 20:39:05 +08:00
|
|
|
|
|
|
|
Now you have created and configured a new Java project it is time to test it. Create a new java
|
|
|
|
file. Here is a starter code for your convenience:
|
|
|
|
@code{.java}
|
|
|
|
import org.opencv.core.Core;
|
|
|
|
import org.opencv.core.CvType;
|
|
|
|
import org.opencv.core.Mat;
|
|
|
|
|
|
|
|
public class Hello
|
|
|
|
{
|
|
|
|
public static void main( String[] args )
|
|
|
|
{
|
|
|
|
System.loadLibrary( Core.NATIVE_LIBRARY_NAME );
|
|
|
|
Mat mat = Mat.eye( 3, 3, CvType.CV_8UC1 );
|
|
|
|
System.out.println( "mat = " + mat.dump() );
|
|
|
|
}
|
|
|
|
}
|
|
|
|
@endcode
|
|
|
|
When you run the code you should see 3x3 identity matrix as output.
|
|
|
|
|
2014-11-28 21:21:28 +08:00
|
|
|
![](images/11-the-code.png)
|
2014-11-27 20:39:05 +08:00
|
|
|
|
|
|
|
That is it, whenever you start a new project just add the OpenCV user library that you have defined
|
|
|
|
to your project and you are good to go. Enjoy your powerful, less painful development environment :)
|