在Java中无法显示ImageIcon

Question

在Java中无法显示ImageIcon

3

这段代码本应该显示一个背景图片和玩家，但实际上只显示了一个粉色的屏幕。我无法确定问题出在哪里，请看我的代码。

package main;

import java.awt.*;
import javax.swing.ImageIcon;    
import javax.swing.JFrame;

public class Images extends JFrame {

    public static void main(String Args[]) {

        DisplayMode dm = new DisplayMode(800, 600, 16, DisplayMode.REFRESH_RATE_UNKNOWN); // This is going to take 4 parameter, first 2 is x and y for resolotion. Bit depth, the number of bits in a cloour
                                                                                            // 16 is your bit depth. the last one is the monitor refresh, it means it will refres how much it wants
        Images i = new Images(); // making an object for this class
        i.run(dm); // making a run method and is taking the dm as a parameter, in this method we are putting stuff on the screen.
    }

    private Screen s; // Creating the Screen, from the Screen.java
    private Image bg; // Background
    private Image pic; // Face icon
    private boolean loaded; // Making the loaded

    //Run method
    private void run(DisplayMode dm) { // this is where we do things for the screen
        setBackground(Color.PINK); // Setting the Background
        setForeground(Color.WHITE); // Setting the ForeGround
        setFont(new Font("Arial", Font.PLAIN, 24)); // setting the font

        s = new Screen(); // now we can call ALL methods from the Screen object
        try {
            s.setFullScreen(dm, this); // This is setting the full screen, it takes in 2 parameters, dm is the display mode, so its setting the display settings, the next part is the this, what is just s, the screen object.
            loadpics(); // calling the loadpics method
            try { // so if that try block works, then it will put it to sleep for 5 seconds
                Thread.sleep(5000); // its doing this because, at the bottom (s.restorescreen) this makes it into a window again. so it needs to show it for 5 seconds.
            } catch (Exception ex) {
            }
        } finally {
            s.restoreScreen();
        }
    }

    // Loads Pictures
    private void loadpics() {
        System.out.println("Loadpics == true");
        bg = new ImageIcon("Users/georgebastow/Picture/background.jpg").getImage(); // Gets the background
        pic = new ImageIcon("Users/georgebastow/Picture/Player.png").getImage(); // Gets the Player
        System.out.println("Loaded == true in da future!");
        loaded = true; // If the pics are loaded then...    
    }

    public void paint(Graphics g) {
        if (g instanceof Graphics2D) { // This has to happen, its saying if g is in the class Graphics2D, so if we have the latest version of java, then this will run 
            Graphics2D g2 = (Graphics2D) g; // Were making the Text smooth but we can only do it on a graphcis2D object.
            g2.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON); // we are making the text aniti alias and turning it on!(it means making the text smooths! :) )
        }
        if(loaded == true){
            System.out.println("Loaded == true3");
            g.drawImage(bg,0,0,null);
            g.drawImage(pic, 170, 180, null);
            System.out.println("Loaded == true4");
        }
    }    
}

在此提前非常感谢你。

- Pilkin

2个回答

3

JFrame不是用于显示Image的合适组件（它的容器）
对于JFrame，使用paint()方法不是显示图像或自定义绘画、图形的正确方式
如果没有在JFrame中使用任何JComponent或有/没有JComponent，则可以使用带有setIcon()的JLabel
如果将JPanel用作其他JComponent的容器，则应该将其放置在JFrame.CENTER区域，并覆盖paintComponent（而不是paint）
更多信息请参见Oracle教程：使用图像

- mKorbel

谢谢mKorbel，我想在不使用JFrame的情况下运行paint。我该如何在没有JFrame的情况下进行绘制？我应该使用什么替代品？ - Pilkin

网页内容由stack overflow 提供, 点击上面的

可以查看英文原文，
原文链接

- Paul Samsotha · Accepted Answer

使用图像时，应通过URL加载它们，使用Class.getResource()方法返回一个URL。如果将String传递给ImageIcon，则会导致查找文件系统中的图像。虽然在开发IDE期间这可能有效，但你会发现在部署时无法正常工作。最好现在进行更改。使用此方法，你需要这样做。

ImageIcon icon = new ImageIcon(Images.class.getResource("/Users/georgebastow/Picture/background.jpg"));

为了使此功能正常工作，您的文件结构需要如下所示。

ProjectRoot
          src
             Users
                  georgebastow
                            Picture
                                  background.jpg

一种更常见的方法是将图片放在资源文件夹中，使用src引用。

ProjectRoot
          src
             resources
                     background.jpg

并使用这个路径

ImageIcon icon = new ImageIcon(Images.class.getResource("/resources/background.jpg"));

当您进行构建时，IDE将把图片转移到类路径中。

附注

Don't paint on top level containers like JFrame. Instead use JPanel or JComponent and override the paintComponent method. if using JPanel, you should also call super.paintComponent in the paintComponent method.

Run you Swing Apps from the Event Dispatch Thread like this

public static void main(String[] args) {
    SwingUtiliities.invokeLater(new Runnable(){
        public void run() {
            new Images();
        }
    });
}

See Initial Thread

Don't call Thread.sleep(). When running from the EDT (like you should), you will block it. Instead use a java.swing.Timer if it's animation you're looking for. Even if it's not animation, still use it! See this example for Timer program.
Also as @mKorbel mentioned, you never add anything to the frame.

更新

运行这个例子。我还忘了提到，当你在JPanel上绘制时，也要重写getPreferredSize()。这将给你的面板一个大小。

src/resources/stackoverflow5.png

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class TestImage {

    public TestImage() {
        JFrame frame = new JFrame("Test Image");
        frame.add(new NewImagePanel());
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setVisible(true);
    }

    public class NewImagePanel extends JPanel {

        private BufferedImage img;

        public NewImagePanel() {
            try {
                img = ImageIO.read(TestImage.class.getResource("/resources/stackoverflow5.png"));
            } catch (IOException ex) {
                System.out.println("Could not load image");
            }
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(600, 600);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            g.drawImage(img, 0, 0, getWidth(), getHeight(), this);
        }
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new TestImage();
            }
        });
    }
}