JavaFX：Maven找不到无效的URL或资源

Question

我正在创建一个JavaFX应用程序并且一直在使用maven框架，所以很自然地，我将sample.fxml放在资源文件夹中：

尽管如此，即使我要访问的代码实际上是之前项目的碳副本，但在此实例中，它拒绝接受该位置存在fxml文件：

public class Main extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception{
        Parent root = FXMLLoader.load(getClass().getResource("/fxml/sample.fxml"));
        primaryStage.setTitle("Hello World");
        primaryStage.setScene(new Scene(root));
        primaryStage.show();
    }


    public static void main(String[] args) {
        launch(args);
    }
}

它吐出来了：

Exception in thread "main" 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$155(LauncherImpl.java:182)
    at java.lang.Thread.run(Thread.java:745)
Caused by: javafx.fxml.LoadException: 
/C:/Users/David/IdeaProjects/FXRpg/target/classes/fxml/sample.fxml

    at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2601)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2579)
    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 sample.Main.start(Main.java:13)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$162(LauncherImpl.java:863)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$175(PlatformImpl.java:326)
    at com.sun.javafx.application.PlatformImpl.lambda$null$173(PlatformImpl.java:295)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$174(PlatformImpl.java:294)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
    ... 1 more
Caused by: java.lang.IllegalArgumentException: Invalid URL: Invalid URL or resource not found
    at javafx.scene.image.Image.validateUrl(Image.java:1118)
    at javafx.scene.image.Image.<init>(Image.java:620)
    at sample.Controller.initialize(Controller.java:31)
    at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2548)
    ... 17 more
Caused by: java.lang.IllegalArgumentException: Invalid URL or resource not found
    at javafx.scene.image.Image.validateUrl(Image.java:1110)
    ... 20 more

POM文件也不会改变任何内容：

<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>groupId</groupId>
    <artifactId>JavaFxApplication</artifactId>
    <version>1.0-SNAPSHOT</version>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>
    <dependencies>
        <dependency>
            <groupId>org.mongodb</groupId>
            <artifactId>mongo-java-driver</artifactId>
            <version>3.0.2</version>
        </dependency>
    </dependencies>
</project>

Answer 1

正如@Robert共享的链接中的答案所详述的那样，加载器的路径似乎是正确的，似乎您的sample.fxml不是。因此，如果您尝试在这些步骤中拆分资源的加载部分

FXMLLoader loader = new FXMLLoader();
loader.setLocation(getClass().getResource("/main.fxml"));
Parent content = loader.load(); 

您会发现失败发生在load，而不是getResource。可能是调试它的正确方法。另外，为了进一步查看.fxml中的错误，需要查看文件内容。

来源 - How to reference javafx fxml files in resource folder?

Answer 2

现在我很好奇。我在IntelliJ：Maven，fmxl子目录中构建项目，如问题所示。以下Main.java工作。

public class Main extends Application {

@Override
public void start(Stage primaryStage) throws Exception{
    Parent root = FXMLLoader.load(getClass().getResource("fxml/sample.fxml"));
    primaryStage.setTitle("Hello World");
    primaryStage.setScene(new Scene(root));
    primaryStage.show();
}

public static void main(String[] args) {
    launch(args);
}

}

如果我移动资源文件，我会收到不同的错误消息：

Caused by: java.lang.NullPointerException: Location is required.
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3207)

为了完整性：POM

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>JavaFXApplication</groupId>
<artifactId>JavaFXApplication</artifactId>
<version>1.0-SNAPSHOT</version>