java - 如何使用 opencv 作为依赖项正确构建 javaFX 应用程序？

Question

我似乎无法正确构建我的项目，我已经厌倦了很多事情，但没有一个起作用。

该项目在 IDE 中运行良好，但一旦我将项目构建为 jar 文件，它就无法运行。

这是主类的代码

@Override
public void start(Stage primaryStage) throws Exception{


    System.loadLibrary(Core.NATIVE_LIBRARY_NAME);//The issue appears to be (line 24)here

    FXMLLoader loader = new FXMLLoader(getClass().getResource("ScreenDesign.fxml"));
    Controller controller = loader.getController();

    //This finds the scene predefined with scene builder
    Parent root = loader.load(getClass().getResource("ScreenDesign.fxml"));

}

这是我运行 jar 文件时得到的结果:

java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)
    at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:767)
Caused by: java.lang.RuntimeException: Exception in Application start method
    at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$154(LauncherImpl.java:182)
    at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.UnsatisfiedLinkError: no opencv_java345 in java.library.path
    at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1867)
    at java.lang.Runtime.loadLibrary0(Runtime.java:870)
    at java.lang.System.loadLibrary(System.java:1122)
    at com.abdrnasr.hl.Main.start(Main.java:24)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$161(LauncherImpl.java:863)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$174(PlatformImpl.java:326)
    at com.sun.javafx.application.PlatformImpl.lambda$null$172(PlatformImpl.java:295)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$173(PlatformImpl.java:294)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$147(WinApplication.java:177)
    ... 1 more
Exception running application com.abdrnasr.hl.Main

以下是使用反编译器输出 jar 的结构: enter image description here

编辑:这是我在没有 System.load() 行的情况下运行代码时遇到的错误。

Exception in Application start method
java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)
    at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:767)
Caused by: java.lang.RuntimeException: Exception in Application start method
    at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$154(LauncherImpl.java:182)
    at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.UnsatisfiedLinkError: org.opencv.videoio.VideoCapture.VideoCapture_4()J
    at org.opencv.videoio.VideoCapture.VideoCapture_4(Native Method)
    at org.opencv.videoio.VideoCapture.<init>(VideoCapture.java:86)
    at com.abdrnasr.hl.Controller.<init>(Controller.java:28)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at java.lang.Class.newInstance(Class.java:442)
    at sun.reflect.misc.ReflectUtil.newInstance(ReflectUtil.java:51)
    at javafx.fxml.FXMLLoader$ValueElement.processAttribute(FXMLLoader.java:927)
    at javafx.fxml.FXMLLoader$InstanceDeclarationElement.processAttribute(FXMLLoader.java:971)
    at javafx.fxml.FXMLLoader$Element.processStartElement(FXMLLoader.java:220)
    at javafx.fxml.FXMLLoader$ValueElement.processStartElement(FXMLLoader.java:744)
    at javafx.fxml.FXMLLoader.processStartElement(FXMLLoader.java:2707)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2527)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2441)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3214)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3175)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3148)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3124)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3104)
    at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3097)
    at com.abdrnasr.hl.Main.start(Main.java:28)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$161(LauncherImpl.java:863)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$174(PlatformImpl.java:326)
    at com.sun.javafx.application.PlatformImpl.lambda$null$172(PlatformImpl.java:295)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$173(PlatformImpl.java:294)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$147(WinApplication.java:177)
    ... 1 more
Exception running application com.abdrnasr.hl.Main

Answer 1

无法直接从可执行 .jar 文件加载 native 库。这是因为像 System.loadLibrary 这样的方法会查找物理库文件。即使您的 native 库位于 jar 内，它们也不会是单独的文件，操作系统也无法加载它们。

如果您使用 Java 9 或更高版本，并且愿意让应用程序使用 Java 模块，则可以选择将 native 库捆绑到 jmod 文件中，因为 jmod 格式可以包含类和 native 库(除其他外)。然后，您可以使用jlink命令创建可执行镜像。请参阅How to deploy a JavaFX 11 Desktop application with a JRE了解更多详情。

如果您不想将应用程序转换为 Java 模块，您可以尝试将 native 库捆绑到 jar 文件中，然后在运行时将其复制到单独的物理文件中:

String libraryEntry;
String os = System.getProperty("os.name");
if (os.contains("Windows")) {
    libraryEntry = Core.NATIVE_LIBRARY_NAME + ".dll";
} else if (os.contains("Mac")) {
    libraryEntry = "lib" + Core.NATIVE_LIBRARY_NAME + ".dylib";
} else {
    libraryEntry = "lib" + Core.NATIVE_LIBRARY_NAME + ".so";
}

Path libraryDir = Files.createTempDirectory("nativelib");
Path libraryFile = libraryDir.resolve(libraryEntry);

try (InputStream libraryResource =
    Main.class.getResourceAsStream("/" + libraryEntry)) {

    Files.copy(libraryResource, libraryFile);
}

System.load(libraryFile);

上面的代码假设您将 .dll、.so 和 .dylib 文件捆绑到 jar 的根目录中。在您的情况下，您需要将 opencv_java345.dll、libopencv_java345.so 和 libopencv_java345.dylib 放入 jar 中。

我实际上还没有尝试过复制 native 库并以这种方式加载它。不过，我已经成功地将 native 库嵌入到 jmod 文件中，并对它们进行了 jlink。