JDK11+Maven开发JavaFx启动问题：java.lang.IllegalAccessError: class com.sun.javafx.fxml.FXMLLoaderHelper

Dear 丶 2023-02-15 14:58 2阅读 0赞

### JDK11 + Maven 开发 JavaFx ###

*  创建 Maven 项目
 *  引入依赖
 *  尝试启动（失败）
 *  遇到问题
 *   *  解决方案

旧电脑上 JDK8 开发 JavaFx 项目就很舒服欸，JDK11 不内置 JavaFx 了，通过 Maven 进行开发遇到的问题还挺多的。。。。

# 创建 Maven 项目 #

创建一个 **quickstart** 的 Maven 项目，然后我们自己去构建目录结构：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzczNDA5NQ_size_16_color_FFFFFF_t_70]  
App 和 Controller 都是 常规类，**Launcher 主要是为了解决一个启动异常的问题**。

# 引入依赖 #

<dependency>
        <groupId>org.openjfx</groupId>
        <artifactId>javafx-controls</artifactId>
        <version>11</version>
    </dependency>
    <dependency>
        <groupId>org.openjfx</groupId>
        <artifactId>javafx-fxml</artifactId>
        <version>11</version>
    </dependency>

# 尝试启动（失败） #

用 fxml 随便搭个界面，正常启动应该都是这样的：

package com.yusael;
    
    import javafx.fxml.FXMLLoader;
    import javafx.scene.Parent;
    import javafx.scene.Scene;
    import javafx.stage.Stage;
    
    public class App extends javafx.application.Application { 
    
        public static void main(String[] args) { 
            launch(args);
        }
    
        public void start(Stage primaryStage) throws Exception { 
            Parent root = FXMLLoader.load(getClass().getResource("/main.fxml"));
            primaryStage.setTitle("My Application");
            primaryStage.setScene(new Scene(root, 600, 400));
            primaryStage.show();
    
        }
    }

居然失败了。。。。。。

# 遇到问题 #

这个问题是使用 fxml 开发才会遇到的，利用 java 代码写界面是没有问题的。

Exception in Application start method
    java.lang.reflect.InvocationTargetException
    	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
    	at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:464)
    	at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:363)
    	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
    	at java.base/sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:1051)
    Caused by: java.lang.RuntimeException: Exception in Application start method
    	at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:900)
    	at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication$2(LauncherImpl.java:195)
    	at java.base/java.lang.Thread.run(Thread.java:834)
    Caused by: java.lang.IllegalAccessError: class com.sun.javafx.fxml.FXMLLoaderHelper (in unnamed module @0x3f176ae0) cannot access class com.sun.javafx.util.Utils (in module javafx.graphics) because module javafx.graphics does not export com.sun.javafx.util to unnamed module @0x3f176ae0
    	at com.sun.javafx.fxml.FXMLLoaderHelper.<clinit>(FXMLLoaderHelper.java:38)
    	at javafx.fxml.FXMLLoader.<clinit>(FXMLLoader.java:2056)
    	at com.yusael.App.start(App.java:47)
    	at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:846)
    	at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:455)
    	at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:428)
    	at java.base/java.security.AccessController.doPrivileged(Native Method)
    	at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:427)
    	at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
    	at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    	at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:174)
    	... 1 more
    Exception running application com.yusael.App
    
    Process finished with exit code 1

## 解决方案 ##

将 App 中的 main 方法抽取到另一个类中，通过以下方式启动：

Application.launch(App.class, args);

具体如下：

package com.yusael;
    
    import javafx.fxml.FXMLLoader;
    import javafx.scene.Parent;
    import javafx.scene.Scene;
    import javafx.stage.Stage;
    
    public class App extends javafx.application.Application { 
    
        public void start(Stage primaryStage) throws Exception { 
            Parent root = FXMLLoader.load(getClass().getResource("/main.fxml"));
            primaryStage.setTitle("My Application");
            primaryStage.setScene(new Scene(root, 600, 400));
            primaryStage.show();
        }
    }

package com.yusael;
    
    import javafx.application.Application;
    
    public class Launcher { 
        public static void main(String args[]){ 
            Application.launch(App.class, args);
        }
    }

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