Question

我试图在java中创建一个图像查看器。我的程序所做的是它需要来自用户的两个输入，在输入1中，用户输入他想要查看图像的文件夹的路径，并且在输入2中，用户还输入他想要的另一个文件夹的路径。查看图像然后按下运行按钮。在按下运行按钮时，来自用户输入的文件夹的第一图像在图像查看器中彼此平行可见，然后用户可以在按下不同按钮时查看下一图像和先前图像。我上述程序的代码如下所示： -

import java.awt.EventQueue;
import java.awt.Font;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;

import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.EmptyBorder;

public class Main extends JFrame {

private JPanel contentPane;
public JTextField textField;
public JTextField textField_1;
public JLabel label;
public JLabel label_1;
int pos = 0;
int pos1 = 0;

/**
 * Launch the application.
 */
public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                Main frame = new Main();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });
}

/**
 * Create the frame.
 */
public Main() {
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setBounds(100, 100, 693, 421);
    contentPane = new JPanel();
    contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
    setContentPane(contentPane);
    contentPane.setLayout(null);

    JLabel lblInput = new JLabel("Input 1");
    lblInput.setFont(new Font("Tahoma", Font.PLAIN, 14));
    lblInput.setBounds(43, 26, 71, 29);
    contentPane.add(lblInput);

    textField = new JTextField();
    textField.setBounds(124, 26, 312, 29);
    contentPane.add(textField);
    textField.setColumns(10);



    JLabel lblExePath = new JLabel("Input 2");
    lblExePath.setFont(new Font("Tahoma", Font.PLAIN, 14));
    lblExePath.setBounds(43, 90, 71, 29);
    contentPane.add(lblExePath);

    textField_1 = new JTextField();
    textField_1.setColumns(10);
    textField_1.setBounds(124, 90, 312, 29);
    contentPane.add(textField_1);

    JButton btnRun = new JButton("Run");
    btnRun.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent arg0) {
            showImage(0);
            showImages(0);

        }
    });
    btnRun.setBounds(505, 95, 89, 23);
    contentPane.add(btnRun);

    label = new JLabel("");
    label.setBounds(43, 151, 262, 176);
    contentPane.add(label);

    label_1 = new JLabel("");
    label_1.setBounds(332, 151, 262, 176);
    contentPane.add(label_1);

    JButton btnPrevious = new JButton("Previous");
    btnPrevious.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent arg0) {
            pos = pos-1;
            if (pos < 0) {
                pos = 0;
            }
            showImage(pos);

            pos1 = pos1-1;
            if (pos1 < 0) {
                pos1 = 0;
            }
            showImages(pos1);
        }
    });
    btnPrevious.setBounds(124, 349, 89, 23);
    contentPane.add(btnPrevious);

    JButton btnNext = new JButton("Next");
    btnNext.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            pos = pos+1;
            if (pos >= getImage().length) {
                pos = getImage().length - 1;
            }
            showImage(pos);

            pos1 = pos1+1;
            if (pos1 >= getImages().length) {
                pos1 = getImages().length - 1;
            }
            showImage(pos1);
        }
    });
    btnNext.setBounds(331, 349, 89, 23);
    contentPane.add(btnNext);

}


public String[] getImage() {
    File file = new File(textField.getText());
    String[] imagesList = file.list();
    return imagesList;
} 

public void showImage(int index) {
    String[] imagesList = getImage();
    String imageName = imagesList[index];
    ImageIcon icon = new ImageIcon(imageName);
    Image image = icon.getImage().getScaledInstance(label.getWidth(), 
    label.getHeight(), Image.SCALE_SMOOTH);
    label.setIcon(new ImageIcon(image));
}

public String[] getImages() {
    File file = new File(textField_1.getText());
    String[] imagesList = file.list();
    return imagesList;
} 

public void showImages(int index) {
    String[] imagesList = getImages();
    String imageName = imagesList[index];
    ImageIcon icon = new ImageIcon(imageName);
    Image image = icon.getImage().getScaledInstance(label_1.getWidth(), 
    label_1.getHeight(), Image.SCALE_SMOOTH);
    label_1.setIcon(new ImageIcon(image));
 }

}

现在，我面临的问题是，一切都运转正常，我能够将用户输入的文件夹文件转换为数组在getimage（）方法中列出并能够将它们转换为不同的数组，但是我无法在showimage（）方法中正确遍历该数组，并且无法使图像显示在屏幕上。如果此代码中还有其他任何问题，请指导，因为我是编程的新手。

Answer 1

如果您打印正在使用的文件名，您将看到它们是基本文件名，没有目录。这意味着它们是相对文件名，它们是否存在完全取决于Java进程本身的当前目录。

java.io.File是一个过时的类。你应该避免使用它。相反，使用java.nio.file package，它不仅会返回完整的文件路径，还会在您尝试列出文件失败时为您提供有用的信息。替换以下两种情况：

String[] imagesList = file.list();

用这个：

String[] imagesList;
try (DirectoryStream<Path> dir = Files.newDirectoryStream(file.toPath())) {
    Collection<String> paths = new ArrayList<>();
    for (Path path : dir) {
        paths.add(path.toString());
    }
    imagesList = paths.toArray(new String[0]);
} catch (IOException e) {
    throw new RuntimeException("Cannot list files in " + file, e);
}

我无法在Java图像查看器中看到图像

1 个答案: