java - Paint Component 在 Eclipse 之外不工作

Question

我真的不明白。当我在 Eclipse 中运行我的程序时，它看起来非常好。它出现在下面:

Chemistry program when run from Eclipse

(请注意，我拖了一些东西来掩盖我的全名，因为这个程序是为学校项目编写的。请忽略它)。注意一切都显示出来了

但是，当我在 eclipse 之外运行程序时...

Chemistry program when run from outside of Eclipse

如您所见，任何与 PaintComponent 相关的对象都不会显示，但 JText 和 JButton 的所有其他对象都会显示。 JOptionPane 消息框也会出现。可能值得注意的是，所有未显示的内容都来自一个 JPanel，它不包含任何显示的内容。

这里是没有出现的面板的代码:

package gui;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Image;
import java.io.File;
import javax.imageio.ImageIO;
import javax.swing.JPanel;

public class TopPane extends JPanel {
    public TopPane(){
        setLayout(new FlowLayout());
    }

    public void paintComponent(Graphics g){
        try{
        String filename = "logo.jpg";
        Image image = ImageIO.read(new File(filename));
        g.drawImage(image, 45, -10, null);

        String intro = "Program by XXXXXXX XXXX\n";
        String intro2 = "The purpose of this program is to make the process of creating a solution";
        String intro3 = "less painful by performing the calculations for how much solute needs to be\n";
        String intro4 = "added to the solvent.  Miscellanious additional information will also be provided.\n";
        String intro5 = "\n";
        String intro6 = "Please enter infromation in the following format:\n";
        String intro7 = "<volume> <molarity> <compound>\n";
        String intro8 = "For example:";
        String intro9 = "5mL 5M H2SO4";
        g.drawString(intro, 30, 70);
        g.drawString(intro2, 30, 95);
        g.drawString(intro3, 30, 110);
        g.drawString(intro4, 30, 125);
        g.drawString(intro5, 30, 140);
        g.drawString(intro6, 30, 155);
        g.drawString(intro7, 30, 170);
        g.drawString(intro8, 30, 195);
        g.drawString(intro9, 30, 210);
        }catch(Exception ex){System.out.println("Failed");}
    }
}

这是运行在 eclipse 之外运行时不起作用的类的代码示例:

package gui;
import java.awt.BorderLayout;
import javax.swing.JFrame;

public class MainFrame extends JFrame{
    public MainFrame(){
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setTitle("Chemistry Lab Assistant");
        setSize(550, 300);

        //Top Frame
        TopPane topPane = new TopPane();
        add(topPane);

        //Input Pane
        InputPane inputPane = new InputPane();
        add(inputPane, BorderLayout.SOUTH);
    }
}

Answer 1

不要尝试在 paintComponent() 方法中读取图像!

更重要的是，到部署时，这些资源可能会变成 embedded-resource .在这种情况下，必须通过 URL 而不是 File 来访问资源。查看info page对于标签，对于形成 URL 的方法。

更多提示:

• g.drawImage(image, 45, -10, null); 最好是 g.drawImage(image, 45, -10, this);<
• 将 catch (Exception e) { .. 形式的代码更改为 catch (Exception e) { e.printStackTrace();//信息量很大! ..
• 不要设置顶级容器的大小。而是布局内容并调用 pack()。