Jpackage - Accessing resources bundled with package

Question

I'm packaging my JavaFX project as installer using JPackageScriptFX, and I've created a folder called "resources" which is present at the basedir of my source package. I've included this folder in my package by passing --app-content resources flag:

$JAVA_HOME/bin/jpackage \
--type $INSTALLER_TYPE \
--dest target/installer \
--input target/libs \
--app-content resources \
--name "$NAME" \
--vendor "$VENDOR" \
--main-class ${MAIN_CLASS}.AppLauncher \
--main-jar ${MAIN_JAR} \
--java-options -Xmx2048m \
--runtime-image target/java-runtime \
--icon ${ICON} \
--app-version ${APP_VERSION} \

This is my source code folders directory structure:

Project
|
|-resources
|         |-icon.png
|
|-src
|
|-pom.xml
.
.
.

After the package is created and installed successfully, the installation directory's structure is:

Project
|
|-bin
|   |-project
|
|-lib
|   |-app
|   |   |-project.jar
|   |   |-project.cfg
|   |
|   |-resources
|   |         |-icon.png
|   |
|   |-runtime
|
|-share

When I'm running the project, I'm getting the FileNotFoundException on method: DBIO.loadResource

public class DBIO {
    private DBIO(){/*NOTHING*/}
    private static InputStream loadResource(String path){
        try{
            return new FileInputStream("resources/"+path);
        }catch(IOException ex){
            ex.printStackTrace();
        }
        return null;
    }
    public static final Image LOGO = new Image(loadResource("icon.png"));
}

java.io.FileNotFoundException: resources/icon.png (No such file or directory)
    at java.base/java.io.FileInputStream.open0(Native Method)
    at java.base/java.io.FileInputStream.open(Unknown Source)
    at java.base/java.io.FileInputStream.<init>(Unknown Source)
    at java.base/java.io.FileInputStream.<init>(Unknown Source)
    at project.app.DBIO.loadResource(DBIO.java:24)
    at project.app.DBIO.<clinit>(DBIO.java:30)
    at project.app.EULAController.<clinit>(EULAController.java:29)
    at java.base/jdk.internal.misc.Unsafe.ensureClassInitialized0(Native Method)
    at java.base/jdk.internal.misc.Unsafe.ensureClassInitialized(Unknown Source)
    at java.base/jdk.internal.reflect.MethodHandleAccessorFactory.ensureClassInitialized(Unknown Source)
    at java.base/jdk.internal.reflect.MethodHandleAccessorFactory.newConstructorAccessor(Unknown Source)
    at java.base/jdk.internal.reflect.ReflectionFactory.newConstructorAccessor(Unknown Source)
    at java.base/java.lang.reflect.Constructor.acquireConstructorAccessor(Unknown Source)
    at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Unknown Source)
    at java.base/java.lang.reflect.Constructor.newInstance(Unknown Source)
    at javafx.fxml.FXMLLoader$ValueElement.processAttribute(FXMLLoader.java:941)
    at javafx.fxml.FXMLLoader$InstanceDeclarationElement.processAttribute(FXMLLoader.java:983)
    at javafx.fxml.FXMLLoader$Element.processStartElement(FXMLLoader.java:230)
    at javafx.fxml.FXMLLoader$ValueElement.processStartElement(FXMLLoader.java:757)
    at javafx.fxml.FXMLLoader.processStartElement(FXMLLoader.java:2853)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2649)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2563)
    at javafx.fxml.FXMLLoader.load(FXMLLoader.java:2531)
    at project.app.App.start(App.java:16)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:839)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:483)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:456)
    at java.base/java.security.AccessController.doPrivileged(Unknown Source)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:455)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
    at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
    at com.sun.glass.ui.gtk.GtkApplication.lambda$runLoop$10(GtkApplication.java:263)
    at java.base/java.lang.Thread.run(Unknown Source)

Exception in Application start method
Exception in thread "main" java.lang.RuntimeException: Exception in Application start method
    at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:893)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$2(LauncherImpl.java:196)
    at java.base/java.lang.Thread.run(Unknown Source)
Caused by: java.lang.ExceptionInInitializerError
    at project.app.EULAController.<clinit>(EULAController.java:29)
    at java.base/jdk.internal.misc.Unsafe.ensureClassInitialized0(Native Method)
    at java.base/jdk.internal.misc.Unsafe.ensureClassInitialized(Unknown Source)
    at java.base/jdk.internal.reflect.MethodHandleAccessorFactory.ensureClassInitialized(Unknown Source)
    at java.base/jdk.internal.reflect.MethodHandleAccessorFactory.newConstructorAccessor(Unknown Source)
    at java.base/jdk.internal.reflect.ReflectionFactory.newConstructorAccessor(Unknown Source)
    at java.base/java.lang.reflect.Constructor.acquireConstructorAccessor(Unknown Source)
    at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Unknown Source)
    at java.base/java.lang.reflect.Constructor.newInstance(Unknown Source)
    at javafx.fxml.FXMLLoader$ValueElement.processAttribute(FXMLLoader.java:941)
    at javafx.fxml.FXMLLoader$InstanceDeclarationElement.processAttribute(FXMLLoader.java:983)
    at javafx.fxml.FXMLLoader$Element.processStartElement(FXMLLoader.java:230)
    at javafx.fxml.FXMLLoader$ValueElement.processStartElement(FXMLLoader.java:757)
    at javafx.fxml.FXMLLoader.processStartElement(FXMLLoader.java:2853)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2649)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2563)
    at javafx.fxml.FXMLLoader.load(FXMLLoader.java:2531)
    at project.app.App.start(App.java:16)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:839)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:483)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:456)
    at java.base/java.security.AccessController.doPrivileged(Unknown Source)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:455)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
    at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
    at com.sun.glass.ui.gtk.GtkApplication.lambda$runLoop$10(GtkApplication.java:263)
    ... 1 more
Caused by: java.lang.NullPointerException: Cannot invoke "java.io.File.toPath()" because "file" is null
    at project.app.DBIO.writeToFile(DBIO.java:73)
    at project.app.Util.log(Util.java:43)
    at project.app.DBIO.loadResource(DBIO.java:26)
    at project.app.DBIO.<clinit>(DBIO.java:30)
    ... 27 more

EDIT: If I copy the resources folder inside Project/bin the project starts working. That means the program is looking for resources folder inside bin. How should I point it to look in the correct location (inside /lib)?

Answer 1

resources folder can be included into a project through jpackage using

--app-content resources

This folder will be present as Project/lib/resources in Linux and Project\resources in Windows.

Access to this folder can be made through:

String resourcesDir = new File(getClass().getProtectionDomain().getCodeSource()
.getLocation().getPath()).getParentFile().getParent()+"/resources/";

Points to notice

• Accessing an image (to load into Image()) would require you to prefix file:// or file:\\.
• If there is a space in the path, you'd require URLDecoder.decode(resourcesDir,"UTF-8").

Answer 2

Preface:

Advanced customization of the package generated is possible by overriding resources used by jpackage, such as background images and template files for properties and scripts. The --resource-dir option is used to provide the overrides to the tool.

If the default resources that jpackage uses when packaging an application don't meet your needs, create a directory and add your customized files to it. If you override a file, your custom file must contain all of the properties that the default contains. Pass the path to the directory to jpackage using the --resource-dir option. The path can be absolute or relative to the current directory.

(https://docs.oracle.com/en/java/javase/21/jpackage/override-jpackage-resources.html)

Explanation about "--resource-dir":

Path to override jpackage resources. It can be an absolute path or relative to the current directory.

Icons, template files, and other resources of jpackage can be overridden by adding replacement resources to this directory.

(https://docs.oracle.com/en/java/javase/21/docs/specs/man/jpackage.html)

Additional information 1:

If you use an external resources dir, then face the problem, that your project wants the resources dir "A" when in development, and the resources dir "B", when packaged.

You may want to create and use a custom made "switch" for pointing to the correct resources dir during development and when your project is packaged.

Or you may rewrite your code to look for resources in your JAR and if it is not available there, look into a specified dir relative to your JAR.

Additional information 2:

I know this is not what you are looking for, but again:

I recommend you to package the resources inside the JAR and if this is not possible for any reason, then package them inside the JAR nevertheless, but extract them on application startup to "userhome/.appname" or somewhere else. Rewrite your code that you application extracts the files first and then uses them from the extracted location. You can extract them to a relative path from your JAR..

Then you will never run into all this troubles.