java - 使用 Windows 外观时 JFileChooser 非常慢

Question

当使用 JFileChooser 以及窗口外观时，我的加载时间约为 21-40 秒。如果我删除外观，代码运行得非常快。我猜问题出在初始化 new JFileChooser("path"); 时。有人能帮我吗 ？这是我的代码

import java.awt.*;
import java.awt.event.*;
import java.io.*;
import javax.swing.*;

public class MainClass {

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            public void run() {
                createGUI();
            }
        });
    }

    private static void createGUI() throws HeadlessException {
        final JFrame frame = new JFrame("JFileChooser Demo");

        try
        {
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }

        final JFileChooser fc = new JFileChooser();
        fc.setMultiSelectionEnabled(true);
        fc.setCurrentDirectory(new File("./feedback"));
        JButton btn1 = new JButton("Show Dialog");
        btn1.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent e) {
                fc.showDialog(frame, "Choose");
            }
        });

        Container pane = frame.getContentPane();
        pane.setLayout(new GridLayout(3, 1, 10, 10));
        pane.add(btn1);

        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack();
        frame.setVisible(true);
    }
}

Answer 1

我也遇到了同样的问题，至少就我而言，它与 Windows 或 Java 的版本无关。

在创建 JFileChooser 期间，Windows 外观 已经尝试通过询问所有可见项目的图标(包括网络共享的图标)来计算当前目录的组合框的大小。就我而言，我的一些网络共享不可用。

这是我在 Java 8 和 Windows 10 上的堆栈跟踪:

Thread [AWT-EventQueue-0]
    Unsafe.park(boolean, long) line: not available [native method]  
    LockSupport.park(Object) line: 175  
    FutureTask<V>.awaitDone(boolean, long) line: 429    
    FutureTask<V>.get() line: 191
    Win32ShellFolderManager2$ComInvoker.invoke(Callable<T>) line: 582   
    ShellFolder.invoke(Callable<T>, Class<E>) line: 518 
    ShellFolder.invoke(Callable<T>) line: 504   
    Win32ShellFolder2.getIcon(boolean) line: 968    
    WindowsFileSystemView(FileSystemView).getSystemIcon(File) line: 243 
    WindowsFileChooserUI$WindowsFileView.getIcon(File) line: 1300   
    JFileChooser.getIcon(File) line: 1609   
    WindowsFileChooserUI$DirectoryComboBoxRenderer.getListCellRendererComponent(JList, Object, int, boolean, boolean) line: 998 
    BasicListUI.updateLayoutState() line: 1361
    BasicListUI.maybeUpdateLayoutState() line: 1311
    BasicListUI$Handler.valueChanged(ListSelectionEvent) line: 2623 
    DefaultListSelectionModel.fireValueChanged(int, int, boolean) line: 184 
    DefaultListSelectionModel.fireValueChanged(int, int) line: 164  
    DefaultListSelectionModel.fireValueChanged() line: 211  
    DefaultListSelectionModel.changeSelection(int, int, int, int, boolean) line: 405    
    DefaultListSelectionModel.changeSelection(int, int, int, int) line: 415 
    DefaultListSelectionModel.setSelectionInterval(int, int) line: 459  
    BasicComboPopup$1(JList<E>).setSelectedIndex(int) line: 2216    
    BasicComboPopup.setListSelection(int) line: 1186    
    BasicComboPopup.access$300(BasicComboPopup, int) line: 65   
    BasicComboPopup$Handler.itemStateChanged(ItemEvent) line: 1015  
    WindowsFileChooserUI$2(JComboBox<E>).fireItemStateChanged(ItemEvent) line: 1223 
    WindowsFileChooserUI$2(JComboBox<E>).selectedItemChanged() line: 1280   
    WindowsFileChooserUI$2(JComboBox<E>).contentsChanged(ListDataEvent) line: 1330  
    WindowsFileChooserUI$DirectoryComboBoxModel(AbstractListModel<E>).fireContentsChanged(Object, int, int) line: 118   
    WindowsFileChooserUI$DirectoryComboBoxModel.setSelectedItem(Object) line: 1140  
    WindowsFileChooserUI$DirectoryComboBoxModel.addItem(File) line: 1111    
    WindowsFileChooserUI$DirectoryComboBoxModel.access$800(WindowsFileChooserUI$DirectoryComboBoxModel, File) line: 1041    
    WindowsFileChooserUI.doDirectoryChanged(PropertyChangeEvent) line: 730  
    WindowsFileChooserUI.access$1100(WindowsFileChooserUI, PropertyChangeEvent) line: 55    
    WindowsFileChooserUI$11.propertyChange(PropertyChangeEvent) line: 821   
    PropertyChangeSupport.fire(PropertyChangeListener[], PropertyChangeEvent) line: 335 
    PropertyChangeSupport.firePropertyChange(PropertyChangeEvent) line: 327 
    PropertyChangeSupport.firePropertyChange(String, Object, Object) line: 263  
    JFileChooser(Component).firePropertyChange(String, Object, Object) line: 8434   
    JFileChooser.setCurrentDirectory(File) line: 598    
    JFileChooser.<init>(File, FileSystemView) line: 344 
    JFileChooser.<init>(File) line: 326 
    FileChooser.<clinit>() line: 15 
    ...

所以我看到两个解决方案:

正如 Joop Eggen 所提到的，在您需要文件选择器之前就初始化它，或者安装您自己的 UI，它会尝试在额外线程中检索图标，并且仅返回那些立即可用的图标。