找不到BlueJ图像

Question

我有一个JavaFX BlueJ项目。以下是简单的目录结构

正如您所看到的，我在同一目录中有Gui.java和map.png个文件。以下是我的代码

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

    primaryStage.setTitle("Dragon Castle");

    Game game = new Game();
    TextArea logArea = new TextArea();

    VBox vbox = new VBox(10);

    // Create maps

    Canvas canvas = new Canvas(770, 630);

    Image map = new Image("map.png"); // Here it is giving error

    GraphicsContext gc = canvas.getGraphicsContext2D();

    // Insert controls

    VBox controlsVbox = new VBox(5);
    controlsVbox.setAlignment(Pos.CENTER);

    HBox buttonHboxR1 = new HBox(5);
    buttonHboxR1.setAlignment(Pos.CENTER); .... Other code

错误：

Exception in Application start method
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$152(LauncherImpl.java:182)
    at com.sun.javafx.application.LauncherImpl$$Lambda$7/22058848.run(Unknown Source)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.IllegalArgumentException: Invalid URL: Invalid URL or resource not found
    at javafx.scene.image.Image.validateUrl(Image.java:1099)
    at javafx.scene.image.Image.<init>(Image.java:608)
    at src.Gui.start(Gui.java:46)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$159(LauncherImpl.java:863)
    at com.sun.javafx.application.LauncherImpl$$Lambda$57/5668924.run(Unknown Source)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$172(PlatformImpl.java:326)
    at com.sun.javafx.application.PlatformImpl$$Lambda$53/812813.run(Unknown Source)
    at com.sun.javafx.application.PlatformImpl.lambda$null$170(PlatformImpl.java:295)
    at com.sun.javafx.application.PlatformImpl$$Lambda$55/19277439.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$171(PlatformImpl.java:294)
    at com.sun.javafx.application.PlatformImpl$$Lambda$54/26973244.run(Unknown Source)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$145(WinApplication.java:101)
    at com.sun.glass.ui.win.WinApplication$$Lambda$43/21354624.run(Unknown Source)
    ... 1 more
Caused by: java.lang.IllegalArgumentException: Invalid URL or resource not found
    at javafx.scene.image.Image.validateUrl(Image.java:1091)
    ... 16 more

找不到图片。我在eclipse中尝试了相同的代码，它的工作原理。我还将map.png放在资源文件夹中，但它仍无法在BlueJ中使用。

Answer 1

来自Image documentation：

  

URL支持的所有URL都可以传递给构造函数。如果   传递的字符串不是有效的URL，而是一个路径，而不是Image   在那种情况下在类路径上搜索。

因此，由于您传递了一个简单的路径，Image构造函数将尝试解析相对于类路径的路径。查看堆栈跟踪，您的Gui类似乎位于名为src的包中（真的???），并且您的图像位于同一个包中。因此，图像的路径应为src/map.png。

从与当前类相同的包中检索图像的更好方法是从类对象获取URL作为资源：

Image map = new Image(getClass().getResource("map.png").toExternalForm());