JavaFX从变量路径加载图像

Question

我正在尝试制作一个简单的骰子软件，它随机生成 1 到 6 之间的数字，并分别输出该状态下的骰子图像。

使用 Image 对象生成图像时，我在获取图像路径时遇到问题。如果我直接输入路径，它就可以工作，但是尝试使用变量会给我错误。

当我单击软件中的“随机”按钮时，会打印以下错误:

Exception in thread "JavaFX Application Thread" 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 dicegui.DiceGUI.lambda$start$0(DiceGUI.java:83)
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
    at javafx.event.Event.fireEvent(Event.java:198)
    at javafx.scene.Node.fireEvent(Node.java:8411)
    at javafx.scene.control.Button.fire(Button.java:185)
    at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:182)
    at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:96)
    at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89)
    at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
    at javafx.event.Event.fireEvent(Event.java:198)
    at javafx.scene.Scene$MouseHandler.process(Scene.java:3757)
    at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485)
    at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762)
    at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:394)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$353(GlassViewEventHandler.java:432)
    at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:431)
    at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
    at com.sun.glass.ui.View.notifyMouse(View.java:937)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$147(WinApplication.java:177)
    at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.IllegalArgumentException: Invalid URL or resource not found
    at javafx.scene.image.Image.validateUrl(Image.java:1110)
    ... 49 more

这是引发错误的代码:

        btnRand.setOnAction((ActionEvent e) ->
        {
            String imgPath = getImage();
            System.out.println("\"" + imgPath + "\"");
            Image img = new Image("\"" + imgPath + "\"");
            //Image img = new Image("img/2.png"); I WAS JUST USING THIS TO TEST
            grid.getChildren().add(new ImageView(img));
            randOutput.setTextFill(Color.GREEN);
        });

这是我的全部代码。值得注意的是，我使用的是 NetBeans。

package dicegui;


import java.util.Random;
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.geometry.HPos;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.GridPane;
import javafx.scene.paint.Color;
import javafx.stage.Stage;

/**
 *
 * @author josef
 */
public class DiceGUI extends Application
{
    public int rollDice()
    {
        int value;
        Random ran = new Random();

        value = ran.nextInt(6) + 1;

        return value;
    }

    public String getImage()
    {
        int value = rollDice() - 1;
        String imageLocation;

        String[] images = new String[6];
        images[0] = "img/1.png";
        images[1] = "img/2.png";
        images[2] = "img/3.png";
        images[3] = "img/4.png";
        images[4] = "img/5.png";
        images[5] = "img/6.png";

        imageLocation = images[value];

        return imageLocation;
    }

    @Override
    public void start(Stage primaryStage)
    {
        primaryStage.setTitle("DiceGUI");

        GridPane grid = new GridPane();
        grid.setAlignment(Pos.CENTER);
        grid.setHgap(10);
        grid.setVgap(10);
        grid.setPadding(new Insets(25, 25, 25, 25));


        Button btnRand = new Button("Randomise");
        GridPane.setHalignment(btnRand, HPos.CENTER);
        grid.add(btnRand, 0, 0);

        Label randOutput = new Label("Not yet randomised");
        randOutput.setTextFill(Color.web("#CD2626"));
        GridPane.setHalignment(randOutput, HPos.CENTER);
        grid.add(randOutput, 0, 1);

        btnRand.setOnAction((ActionEvent e) ->
        {
            String imgPath = getImage();
            System.out.println("\"" + imgPath + "\"");
            Image img = new Image("\"" + imgPath + "\"");
            //Image img = new Image("img/2.png");
            grid.getChildren().add(new ImageView(img));
            randOutput.setTextFill(Color.GREEN);
        });





        Scene scene = new Scene(grid, 300, 300);
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args)
    {
        launch(args);
    }

}

文件结构如下:

Answer 1

您在字符串的开头和结尾使用双引号，这会产生无效的文件路径，例如“img/5.png”。有效路径为 img/5.png

只需使用imgPath加载图像:

Image img = new Image(imgPath);

或者，您可以使用类加载器来获取资源:

Image img = new Image(getClass().getResourceAsStream("/" + imgPath));