How to use OpenCV build (opencv and opencv_contrib) in a Maven project

Question

I compiled openCV and OpenCV_contrib library and had the resulting build/bin/opencv-411.jar and libraries .so in build/lib/. Now I am wondering how can I add these to my Maven project?

I was using that Maven repository but the contrib modules are not available.

I tried including the jar as a dependency like here with:

<dependency>
    <groupId>org.opencv</groupId>
    <artifactId>opencv-411</artifactId>
    <version>4.1.0</version> 
    <scope>system</scope>
    <systemPath>${resourcesfolder}/opencv-411.jar</systemPath>
</dependency>

I get no error when I launch clean javafx:compile but when I launch clean javafx:run a lot of OpenCV errors appear :

[ERROR] COMPILATION ERROR :

[INFO] -------------------------------------------------------------
[ERROR] /home/.../src/main/java/model/VideoModel.java:[3,23] package org.opencv.core does not exist
[ERROR] /home/.../src/main/java/model/VideoModel.java:[4,23] package org.opencv.core does not exist
[ERROR] /home/.../src/main/java/model/VideoModel.java:[5,26] package org.opencv.videoio does not exist
[ERROR] /home/.../src/main/java/model/VideoModel.java:[6,26] package org.opencv.videoio does not exist
[ERROR] /home/.../src/main/java/model/VideoModel.java:[25,17] cannot find symbol
     symbol:   class VideoCapture
     location: class model.VideoModel
[ERROR] /home/.../src/main/java/model/VideoModel.java:[26,17] cannot find symbol
     symbol:   class Mat

I also had a look to that but he deployed his new jar containing the executables and libraries in a remote repository. The interesting part is the jar creation, so I tried to do the same with opencv-411.jar and lib/ folder with:

cp opencv-411.jar opencv-411-new.jar
jar -uvf opencv-411-new.jar lib/

and kept the dependency as above, but raised the same errors...

What should I do?

Rafutk · Accepted Answer · 2019-07-26 07:58:08Z

Thanks to the answers, I came to the solution for including OpenCV jar and libs to Maven:

install the jar in the maven local repository with:

mvn install:install-file -Dfile=/home/.../src/main/resources/opencv.jar -DgroupId=org -DartifactId=opencv -Dversion=4.1.1 -Dpackaging=jar

create the dependency in pom.xml:

<dependency> 
 <groupId>org</groupId> 
 <artifactId>opencv</artifactId>
 <version>4.1.1</version>  
</dependency>

Now that the jar is included, we must add the OpenCV libraries somehow.

Just load the library in your app with:

System.load("/path/to/lib/libopencv_java411.so");

For the UI tests, as the maven-surefire-plugin uses a special JVM, you have to specify the lib folder to the java.library.path:

<plugin>
 <groupId>org.apache.maven.plugins</groupId>
 <artifactId>maven-surefire-plugin</artifactId>
 <version>2.22.2</version>
 <configuration>
  <argLine>-Djava.library.path=${project.build.outputDirectory}/lib</argLine>
 </configuration>
</plugin>

Please feel free to edit if you have a better solution or corrections to add.

stacker · Accepted Answer · 2019-07-23 09:30:22Z

0

Maven expects the artifacts (.jar files, etc.) in $USER_HOME/.m2 since you compiled opencv yourself you also need to install the file (as 3rd party module) in the local maven repository:

mvn install:install-file -Dfile=<path-to-file> -DgroupId=<group-id> \
    -DartifactId=<artifact-id> -Dversion=<version> -Dpackaging=<packaging>

Where the variables need to match those you use in you pom.xml and packaging must be set to jar.

See also: https://maven.apache.org/guides/mini/guide-3rd-party-jars-local.html

answered Jul 23, 2019 at 9:30

stacker

69.1k29 gold badges143 silver badges214 bronze badges

3 Comments

Rafutk Over a year ago

Thanks for the quick answer, I did the command

mvn install:install-file -Dfile=/home/.../src/main/resources/opencv.jar -DgroupId=org   -DartifactId=opencv -Dversion=4.1.1 -Dpackaging=jar

and removed scope and systemPath from the dependency. But I get "Error: Could not find or load main class" from javafx-maven-plugin, it was working before..

stacker Over a year ago

In your pom snippet you're refering to version 4.1.0 (not 4.1.1) you could try mvn -x (for more detailed output)

Rafutk Over a year ago

The version was also modified so it is not the problem. I added the OpenCV library path to java.lib.path with <argLine>-Djava.library.path=/home/.../target/classes/lib</argLine> to maven-surefire-plugin and the clean package maven goals worked (launched every test)! But the clean javafx:run still throw the "Could not find or load main class ..."

Kamal Kumar · Accepted Answer · 2019-07-23 09:40:32Z

0

mvn install:install-file -Dfile=C:\Users\your jar path -DgroupId=org.opencv -DartifactId=opencv-411 -Dversion=4.1.0 -Dpackaging=jar you can use this one may be solve your issue

answered Jul 23, 2019 at 9:40

Kamal Kumar

1941 silver badge13 bronze badges

1 Comment

Rafutk Over a year ago

Thanks for your answer, I did that command, changed the dependency and added the OpenCV libs path to maven-surefire-plugin. The package goal works perfectly, but the javafx:run does not work because it doesn't find the main class..

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