在Linux上使用Java Swing遇到麻烦，并获得设置外观和获取文件类型图标

Question

我遇到了两个问题，我相信这有点相关。源代码，终端输出和GUI输出的屏幕截图不足。 Linux Java是OpenJDK，Windows/Mac是Oracle，以防有所不同。所有的帮助都非常感谢。

首先，在Kubuntu版本20.04（KDE）上，在设置系统默认外观和感觉时，我会得到金属外观和感觉，但是它在Windows，Mac和Ubuntu 22.04（Gnome）上正常工作。我查看了Java API文档（ https://docs.oracle。 com/javase/tutorial/uiswing/lookandfeel/plaf.html ），他们说没有gtk+的系统（我认为kubuntu是这种情况，因为它使用kde而不是gnome）应该默认图像和感觉，并有图案的外观和感觉，不是金属。但是，即使终端输出同时显示GTK+和Motif外观和感觉，Kubuntu仍然默认为金属。为什么Kubuntu这样做？我知道如何在可用外观列表中解析文本，以选择合适的外观和感觉，但希望在可能的情况下避免。

平台	默认外观和感觉
Solaris，带有GTK+ 2.2或更高版本的Linux	+
其他Solaris，Linux	Motif
Windows	Macintosh
Macintosh	第二，在Ubuntu和Kubuntu

上，我无法获得文件的文件类型（例如Triangular squiggly Line for PDF），但是PDF）我可以在Windows和Mac上。通过Jfilechooser浏览和请求文件图标时，它们都不会显示。我在Kubuntu 20.04检查了三个已知用Java编写的程序（NetBeans，Intellij和Eclipse），我发现Eclipse能够正确地显示其文件Chooser中的图标，Intellij和Intellij显示了不同但仍显示的文件图标，这表明那里表明那里有不同必须某种方式获得图标。如何获得文件类型图标？

• eclipse文件choser： https://i.sstatic.net/8hga8.png8.png
• ： https://i.sstatic.net.net/jfsl8.png href =“ https://i.sstatic.net/nsspl.png” rel =“ nofollow noreferrer”> https://i.sstatic.net/nsspl.png

>

public static void main(String[] args)
    {
        //Display system information
        String os_name = System.getProperty("os.name");
        String os_arch = System.getProperty("os.arch");
        String os_ver = System.getProperty("os.version");
        System.out.println("Current System: " + os_name + " " + os_arch + " " + os_ver);
        String java_name = System.getProperty("java.vm.name");
        String java_vendor = System.getProperty("java.vm.vendor");
        String java_ver = System.getProperty("java.vm.version");
        System.out.println("Current Java VM: " + java_name + " (" + java_vendor + ") " + java_ver);
        System.out.println();

        //initial Look and Feel
        LookAndFeel feel = UIManager.getLookAndFeel();
        System.out.println("Look and Feel initially loaded when Java starts");
        System.out.println("Name: " + feel.getName());
        System.out.println("ID: " + feel.getID());
        System.out.println("Description: " + feel.getDescription());
        System.out.println();
        
        //get a list of all the look and feels installed on this system
        UIManager.LookAndFeelInfo[] info1 = UIManager.getInstalledLookAndFeels();
        System.out.println("List of installed Look and Feels:");
        for (int i = 0; i < info1.length; i++)
        {
            System.out.println(info1[i]);
        }
        System.out.println();
        
        //set Look and feel to what the system says is the default Look and Feel.
        try
        {
            String systemLF = UIManager.getSystemLookAndFeelClassName();
            System.out.println("Default system look and feel: " + systemLF);
            System.out.println("Trying to set Default system look and feel");
            System.out.println();
            UIManager.setLookAndFeel(systemLF);         
        }
        catch(Exception e)
        {
            System.out.println("Error with setting default system Look and Feel");
            System.out.println();
        }

        //new system Look and Feel
        LookAndFeel feel2 = UIManager.getLookAndFeel();
        System.out.println("Look and Feel after trying to set default system Look and Feel");
        System.out.println("Name: " + feel2.getName());
        System.out.println("ID: " + feel2.getID());
        System.out.println("Description: " + feel2.getDescription());
        System.out.println();

        JFileChooser chooser = new JFileChooser();
        chooser.showOpenDialog(null);
        File file = chooser.getSelectedFile();
        //System.out.println(file.getAbsolutePath());
        /*Doesn't work on Mac
        Icon icon = FileSystemView.getFileSystemView().getSystemIcon(file);*/
        final javax.swing.JFileChooser fc = new javax.swing.JFileChooser();       
        Icon icon = fc.getUI().getFileView(fc).getIcon(file); //get filetype icon for chosen file
        JOptionPane.showMessageDialog(null, "This is the file icon", "", JOptionPane.INFORMATION_MESSAGE, icon);
    }

屏幕截图：

• kubuntu 20.04
  • https://i.sstatic.net.net/7ty1r.png
  • https://i.sstatic.net/c9nbe.png
• ubuntu 22.04
  • https://i.sstatic.net/dlnbq.jpg
  • https://i.sstatic.net/6yb1u.jpg
• Windows
  • https://i.sstatic.net/smvbj.png
  • https://i.sstatic.net.net/2zplp.png
• Mac
  • https://i.sstatic.net/635ze.png
  • https://i.sstatic.net/i2kre.png

控制台输出：

Current System: Linux amd64 5.4.0-110-generic
Current Java VM: OpenJDK 64-Bit Server VM (Private Build) 11.0.15+10-Ubuntu-0ubuntu0.20.04.1

Look and Feel initially loaded when Java starts
Name: Metal
ID: Metal
Description: The Java(tm) Look and Feel

List of installed Look and Feels:
javax.swing.UIManager$LookAndFeelInfo[Metal javax.swing.plaf.metal.MetalLookAndFeel]
javax.swing.UIManager$LookAndFeelInfo[Nimbus javax.swing.plaf.nimbus.NimbusLookAndFeel]
javax.swing.UIManager$LookAndFeelInfo[CDE/Motif com.sun.java.swing.plaf.motif.MotifLookAndFeel]
javax.swing.UIManager$LookAndFeelInfo[GTK+ com.sun.java.swing.plaf.gtk.GTKLookAndFeel]

Default system look and feel: javax.swing.plaf.metal.MetalLookAndFeel
Trying to set Default system look and feel

Look and Feel after trying to set default system Look and Feel
Name: Metal
ID: Metal
Description: The Java(tm) Look and Feel

22.04：

Current System: Linux amd64 5.15.0-27-generic
Current Java VM: OpenJDK 64-Bit Server VM (Private Build) 11.0.15+10-Ubuntu-0ubuntu0.22.04.1

Look and Feel initially loaded when Java starts
Name: Metal
ID: Metal
Description: The Java(tm) Look and Feel

List of installed Look and Feels:
javax.swing.UIManager$LookAndFeelInfo[Metal javax.swing.plaf.metal.MetalLookAndFeel]
javax.swing.UIManager$LookAndFeelInfo[Nimbus javax.swing.plaf.nimbus.NimbusLookAndFeel]
javax.swing.UIManager$LookAndFeelInfo[CDE/Motif com.sun.java.swing.plaf.motif.MotifLookAndFeel]
javax.swing.UIManager$LookAndFeelInfo[GTK+ com.sun.java.swing.plaf.gtk.GTKLookAndFeel]

Default system look and feel: com.sun.java.swing.plaf.gtk.GTKLookAndFeel
Trying to set Default system look and feel

Gtk-Message: 22:12:59.057: Failed to load module "canberra-gtk-module"
Look and Feel after trying to set default system Look and Feel
Name: GTK look and feel
ID: GTK
Description: GTK look and feel

Windows输出：

Current System: Windows 10 amd64 10.0
Current Java VM: Java HotSpot(TM) 64-Bit Server VM (Oracle Corporation) 15.0.1+9-18

Look and Feel initially loaded when Java starts
Name: Metal
ID: Metal
Description: The Java(tm) Look and Feel

List of installed Look and Feels:
javax.swing.UIManager$LookAndFeelInfo[Metal javax.swing.plaf.metal.MetalLookAndFeel]
javax.swing.UIManager$LookAndFeelInfo[Nimbus javax.swing.plaf.nimbus.NimbusLookAndFeel]
javax.swing.UIManager$LookAndFeelInfo[CDE/Motif com.sun.java.swing.plaf.motif.MotifLookAndFeel]
javax.swing.UIManager$LookAndFeelInfo[Windows com.sun.java.swing.plaf.windows.WindowsLookAndFeel]
javax.swing.UIManager$LookAndFeelInfo[Windows Classic com.sun.java.swing.plaf.windows.WindowsClassicLookAndFeel]

Default system look and feel: com.sun.java.swing.plaf.windows.WindowsLookAndFeel
Trying to set Default system look and feel

Look and Feel after trying to set default system Look and Feel
Name: Windows
ID: Windows
Description: The Microsoft Windows Look and Feel

MAC输出：

Current System: Mac OS X x86_64 10.16
Current Java VM: Java HotSpot(TM) 64-Bit Server VM (Oracle Corporation) 13.0.1+9

Look and Feel initially loaded when Java starts
Name: Mac OS X
ID: Aqua
Description: Aqua Look and Feel for Mac OS X

List of installed Look and Feels:
javax.swing.UIManager$LookAndFeelInfo[Metal javax.swing.plaf.metal.MetalLookAndFeel]
javax.swing.UIManager$LookAndFeelInfo[Nimbus javax.swing.plaf.nimbus.NimbusLookAndFeel]
javax.swing.UIManager$LookAndFeelInfo[CDE/Motif com.sun.java.swing.plaf.motif.MotifLookAndFeel]
javax.swing.UIManager$LookAndFeelInfo[Mac OS X com.apple.laf.AquaLookAndFeel]

Default system look and feel: com.apple.laf.AquaLookAndFeel
Trying to set Default system look and feel

Look and Feel after trying to set default system Look and Feel
Name: Mac OS X
ID: Aqua
Description: Aqua Look and Feel for Mac OS X