导航...

Question

我尝试在网络上搜索此问题的帮助，但找不到任何答案。此时我有一个工作程序，允许您选择图像文件并显示它。我想通过允许用户选择多个文件然后选择要显示的文件来构建此基础。例如，用户将选择图像并将其显示。然后，他可以单击一个按钮，允许其他图像排队等待，也许按钮会显示在点击时，图像将加载到框架中。任何人都可以指导我如何实施这个方向吗？非常感谢你的帮助！

这是我目前的代码实现：

import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import javax.swing.*;
import javax.swing.filechooser.FileNameExtensionFilter;
import java.util.ArrayList;



public class Images extends JFrame{
    JButton button;
    JButton button2;
    JButton button3;
    JLabel label;
    ArrayList<File> images = new ArrayList<>();
    int selectedImageIndex =0;

    public Images(){
    super("Java Image Selector");
    button = new JButton("Select");
    button.setBounds(300,300,100,40);
    button2 = new JButton("Next Image");
    button2.setBounds(250,250,100,40);
    button3 = new JButton("Previous Image");
    button3.setBounds(350,350,100,40);
    label = new JLabel();
    label.setBounds(10,10,670,250);
    add(button);
    add(button2);
    add(button3);
    add(label);

    button.addActionListener(new ActionListener() {

        public void actionPerformed(ActionEvent e) {



          JFileChooser file = new JFileChooser();
          file.setMultiSelectionEnabled(true);
          File selected[] = file.getSelectedFiles();
          file.setCurrentDirectory(new File(System.getProperty("user.home")));
          //filter the files
          FileNameExtensionFilter filter = new FileNameExtensionFilter("*.Images", "jpg","gif","png");
          file.addChoosableFileFilter(filter);
          int result = file.showSaveDialog(null);
           //if the user click on save in Jfilechooser
          if(result == JFileChooser.APPROVE_OPTION){
              File selectedFile = file.getSelectedFile();
              String path = selectedFile.getAbsolutePath();
              File[] files = file.getSelectedFiles();
              for (File open : files) {
                  images.add(open);
              }
              startProgram(selectedImageIndex);
          }
           //if the user click on save in Jfilechooser

          else if(result == JFileChooser.CANCEL_OPTION){
              System.out.println("No File Selected");
          }
        }
    });

    button2.addActionListener(new ActionListener() { 
      public void actionPerformed(ActionEvent e) { 
         goToNextImages();
      } 
    });

    button3.addActionListener(new ActionListener() { 
      public void actionPerformed(ActionEvent e) { 
        goToPreviousImage();
      } 
    });



    setLayout(null);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setLocationRelativeTo(null);
    setSize(700,400);
    setVisible(true);
    }

     // Methode to resize imageIcon with the same size of a Jlabel
    public ImageIcon ResizeImage(String ImagePath)
    {
        ImageIcon MyImage = new ImageIcon(ImagePath);
        Image img = MyImage.getImage();
        Image newImg = img.getScaledInstance(label.getWidth(), label.getHeight(), Image.SCALE_SMOOTH);
        ImageIcon image = new ImageIcon(newImg);
        return image;
    }

    public void setImage(int index){

      if (index<images.size()) {
        File imageFile = images.get(index);
        String path = imageFile.getAbsolutePath();
        selectedImageIndex = index;
        label.setIcon(ResizeImage(path));
        //read the file and set the image
      }else{
        System.out.println("no image found");
      }

    }

   public void goToNextImages(){
      ++selectedImageIndex;
      setImage(selectedImageIndex);
   }

   public void goToPreviousImage(){
      --selectedImageIndex;
       setImage(selectedImageIndex);
   }

   public void startProgram(int index){
       setImage(index);
   }

    public static void main(String[] args){
        new Work();
    }
   }

Answer 1

好的，让我们稍微分解一下，你基本上需要：

某种＆＃34;型号＆＃34;其中包含图像文件列表
某种＆＃34;观点＆＃34;显示当前图像
某种＆＃34;控制器＆＃34;它管理视图和模型之间的关系
某种＆＃34;型号＆＃34;跟踪当前可见图像并知道它是否可以加载下一张或上一张图像
某种＆＃34;观点＆＃34;允许用户控制导航
控制一切的一些方法

好吧，如果那不是Model-View-Controller，我就不知道是什么......

好的，因为我喜欢明确定义的合同和责任范围，我喜欢从接口开始......

导航...

public interface NavigationModel {
    public boolean next();
    public boolean previous();
    public int getIndex();
    public void addChangeListener(ChangeListener listener);
    public void removeChangeListener(ChangeListener listener);
    public boolean canNavigateForward();
    public boolean canNavigateBack();
}

public interface NavigationViewDelegate {
    public boolean next(NavigationView view);
    public boolean previous(NavigationView view);
    public boolean canNavigateForward();
    public boolean canNavigateBack();
}

public interface NavigationView {
    public void setDelegate(NavigationViewDelegate delegate);
    public NavigationViewDelegate getDelegate();
    public JComponent getView();
    public void stateChanged();
}

public interface NavigationContoller {
    public NavigationView getView();
    public NavigationModel getModel();
    public void addChangeListener(ChangeListener listener);
    public void removeChangeListener(ChangeListener listener);
}

好的，所以代表允许视图询问＆＃34;某人＆＃34;有关当前状态的更多信息，这通常是控制器。该模型触发ChangeEvent，告诉任何感兴趣的人，模型的状态以某种方式发生了变化，控制器将它们全部绑定在一起。

默认实施

通常情况下，我会有一系列的抽象实现，但为了简洁起见，我已经直接实现了

public class DefaultNavigationController implements NavigationContoller {

    private NavigationView view;
    private NavigationModel model;

    private ChangeListener modelChangeListener;
    private final Set<ChangeListener> changeListeners;

    public DefaultNavigationController(NavigationView view, NavigationModel model) {
        Objects.requireNonNull(model, "Model can not be null");
        Objects.requireNonNull(view, "View can not be null");
        this.view = view;
        this.model = model;

        view.setDelegate(new NavigationViewDelegate() {
            @Override
            public boolean next(NavigationView view) {
                return getModel().next();
            }

            @Override
            public boolean previous(NavigationView view) {
                return getModel().previous();
            }

            @Override
            public boolean canNavigateForward() {
                NavigationModel model = getModel();
                return model.canNavigateForward();
            }

            @Override
            public boolean canNavigateBack() {
                NavigationModel model = getModel();
                return model.canNavigateBack();
            }
        });

        changeListeners = new HashSet<>(25);

        modelChangeListener = new ChangeListener() {
            @Override
            public void stateChanged(ChangeEvent e) {
                getView().stateChanged();
                fireStateChanged();
            }
        };
        this.model.addChangeListener(modelChangeListener);
        getView().stateChanged();
    }

    @Override
    public NavigationView getView() {
        return view;
    }

    @Override
    public NavigationModel getModel() {
        return model;
    }

    protected void setModel(NavigationModel model) {
        this.model.removeChangeListener(modelChangeListener);
        this.model = model;
        this.model.addChangeListener(modelChangeListener);
        getView().stateChanged();
        fireStateChanged();
    }

    @Override
    public void addChangeListener(ChangeListener listener) {
        changeListeners.add(listener);
    }

    @Override
    public void removeChangeListener(ChangeListener listener) {
        changeListeners.remove(listener);
    }

    protected void fireStateChanged() {
        ChangeEvent evt = new ChangeEvent(this);
        for (ChangeListener listener : changeListeners) {
            listener.stateChanged(evt);
        }
    }

}

public class DefaultNavigationModel implements NavigationModel {

    private final int minValue;
    private final int maxValue;
    private int currentIndex;
    private final Set<ChangeListener> changeListeners;

    public DefaultNavigationModel(int minValue, int maxValue) {
        this.maxValue = maxValue;
        this.minValue = minValue;
        currentIndex = minValue;

        changeListeners = new HashSet<>(25);
    }

    @Override
    public boolean next() {
        if (currentIndex + 1 < maxValue) {
            currentIndex++;
            fireStateChanged();
        }
        return canNavigateForward();
    }

    @Override
    public boolean previous() {
        if (currentIndex >= minValue) {
            currentIndex--;
            fireStateChanged();
        }
        return canNavigateBack();
    }

    @Override
    public int getIndex() {
        return currentIndex;
    }

    @Override
    public void addChangeListener(ChangeListener listener) {
        changeListeners.add(listener);
    }

    @Override
    public void removeChangeListener(ChangeListener listener) {
        changeListeners.remove(listener);
    }

    protected void fireStateChanged() {
        ChangeEvent evt = new ChangeEvent(this);
        for (ChangeListener listener : changeListeners) {
            listener.stateChanged(evt);
        }
    }

    @Override
    public boolean canNavigateForward() {
        return size() > 0 && currentIndex < maxValue - 1;
    }

    @Override
    public boolean canNavigateBack() {
        return size() > 0 && currentIndex > minValue;
    }

    public int size() {
        return maxValue - minValue;
    }

}

public class DefaultNavigationView extends JPanel implements NavigationView {

    private JButton nextButton;
    private JButton previousButton;

    private NavigationViewDelegate delegate;

    public DefaultNavigationView() {
        setLayout(new GridBagLayout());
        nextButton = new JButton(">");
        previousButton = new JButton("<");

        nextButton.setEnabled(false);
        previousButton.setEnabled(false);

        GridBagConstraints gbc = new GridBagConstraints();
        gbc.weightx = 1;
        gbc.anchor = GridBagConstraints.WEST;
        add(previousButton, gbc);
        gbc.anchor = GridBagConstraints.EAST;
        add(nextButton, gbc);

        nextButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                NavigationViewDelegate delegate = getDelegate();
                if (delegate != null) {
                    nextButton.setEnabled(delegate.next(DefaultNavigationView.this));
                }
            }
        });
        previousButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                NavigationViewDelegate delegate = getDelegate();
                if (delegate != null) {
                    previousButton.setEnabled(delegate.previous(DefaultNavigationView.this));
                }
            }
        });
    }

    @Override
    public NavigationViewDelegate getDelegate() {
        return delegate;
    }

    @Override
    public JComponent getView() {
        return this;
    }

    @Override
    public void setDelegate(NavigationViewDelegate delegate) {
        this.delegate = delegate;
        stateChanged();
    }

    @Override
    public void stateChanged() {
        nextButton.setEnabled(delegate != null && delegate.canNavigateForward());
        previousButton.setEnabled(delegate != null && delegate.canNavigateBack());
    }

}

这里需要注意的重要一点是导航API并不关心图像，它只关心＆＃34;范围＆＃34;它目前的价值是什么。

例如，这可能意味着您可以将视图更改为基于JSlider或包含JComboBox或您想要允许用户更改索引的控件以及其他内容代码无法照顾。

图像...

以类似的方式，我们定义了一个简单的模型，它维护一个代表可用图像的File列表，一个显示它们的视图和一个绑定它们的控制器......

public interface ImageModel {
    public File getImageAt(int index);
    public int size();
}

public interface ImageView {
    public void loadImageAt(int index);
    public void setDelegate(ImageViewDelegate delegate);
    public ImageViewDelegate getDelegate();
    public JComponent getView();
}

public interface ImageViewDelegate {
    public File imageAt(ImageView view, int index);
}

public interface ImageViewController {
    public ImageModel getModel();
    public ImageView getView();
    public void loadImageAt(int index);
}

默认实施......

同样，为简洁起见，直接执行......

public class DefaultImageModel implements ImageModel {

    private List<File> images;
    private int currentImage = -1;

    public DefaultImageModel(List<File> images) {
        this.images = new ArrayList<>(images);
    }

    @Override
    public File getImageAt(int index) {
        return images.get(index);
    }

    @Override
    public int size() {
        return images.size();
    }

}

public class DefaultImageController implements ImageViewController {

    private ImageView view;
    private ImageModel model;

    public DefaultImageController(ImageView view, ImageModel model) {
        Objects.requireNonNull(model, "Model can not be null");
        Objects.requireNonNull(view, "View can not be null");
        this.view = view;
        this.model = model;

        view.setDelegate(new ImageViewDelegate() {
            @Override
            public File imageAt(ImageView view, int index) {
                return getModel().getImageAt(index);
            }
        });
    }

    public void setModel(ImageModel model) {
        Objects.requireNonNull(model, "Model can not be null");
        this.model = model;
    }

    @Override
    public ImageModel getModel() {
        return model;
    }

    @Override
    public ImageView getView() {
        return view;
    }

    @Override
    public void loadImageAt(int index) {
        getView().loadImageAt(index);
    }

}

public class DefaultImageViewPane extends JPanel implements ImageView {

    private ImageViewDelegate delegate;
    private BufferedImage img = null;

    public DefaultImageViewPane() {
    }

    @Override
    public Dimension getPreferredSize() {
        return img == null ? new Dimension(200, 200) : new Dimension(img.getWidth(), img.getHeight());
    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        if (img != null) {
            Graphics2D g2d = (Graphics2D) g.create();
            int x = (getWidth() - img.getWidth()) / 2;
            int y = (getHeight() - img.getHeight()) / 2;
            g2d.drawImage(img, x, y, this);
            g2d.dispose();
        }
    }

    @Override
    public void setDelegate(ImageViewDelegate delegate) {
        this.delegate = delegate;
    }

    @Override
    public ImageViewDelegate getDelegate() {
        return delegate;
    }

    @Override
    public JComponent getView() {
        return this;
    }

    @Override
    public void loadImageAt(int index) {
        ImageViewDelegate delegate = getDelegate();
        if (delegate != null) {             
            img = null;
            File file = delegate.imageAt(this, index);
            if (file != null) {
                try {
                    img = ImageIO.read(file);
                } catch (IOException ex) {
                    ex.printStackTrace();
                }
            }
            revalidate();
            repaint();
        }
    }
}

全部放在一起......

现在，您可能想知道这一切是如何组合在一起的？

这是一个很好的例子，说明控制器如何协同工作，实际上彼此不了解，相互提供信息以实现所需的结果......

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Objects;
import java.util.Set;
import java.util.prefs.Preferences;
import javax.imageio.ImageIO;
import javax.swing.AbstractAction;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JToolBar;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.filechooser.FileNameExtensionFilter;

public class Test {

    public static void main(String[] args) {
        new Test();
    }

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new MainPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class MainPane extends JPanel {

        private DefaultImageController imageController;
        private DefaultNavigationController navigationController;

        public MainPane() {
            setLayout(new BorderLayout());

            ImageView imageView = new DefaultImageViewPane();
            ImageModel imageModel = new DefaultImageModel(new ArrayList<>());
            imageController = new DefaultImageController(imageView, imageModel);

            add(new JScrollPane(imageController.getView().getView()));

            NavigationView navView = new DefaultNavigationView();
            NavigationModel navModel = new DefaultNavigationModel(0, 0);
            navigationController = new DefaultNavigationController(navView, navModel);
            navigationController.addChangeListener(new ChangeListener() {
                @Override
                public void stateChanged(ChangeEvent e) {
                    NavigationContoller controller = (NavigationContoller) e.getSource();
                    imageController.loadImageAt(controller.getModel().getIndex());
                }
            });

            add(navigationController.getView().getView(), BorderLayout.SOUTH);

            JToolBar tb = new JToolBar();
            tb.add(new AbstractAction("Browse") {
                @Override
                public void actionPerformed(ActionEvent e) {
                    String lastDirectory = Preferences.userNodeForPackage(MainPane.class).get("Images.lastDirectory", System.getProperty("user.home"));
                    JFileChooser fc = new JFileChooser();
                    File lastPath = new File(lastDirectory);
                    if (lastPath.exists() && lastPath.isDirectory()) {
                        fc.setCurrentDirectory(new File(lastDirectory));
                    }
                    fc.addChoosableFileFilter(new FileNameExtensionFilter("Image files", ImageIO.getReaderFileSuffixes()));
                    fc.setMultiSelectionEnabled(true);
                    if (fc.showOpenDialog(MainPane.this) == JFileChooser.APPROVE_OPTION) {
                        lastDirectory = fc.getCurrentDirectory().getPath();
                        Preferences.userNodeForPackage(MainPane.class).put("Images.lastDirectory", lastDirectory);

                        File[] files = fc.getSelectedFiles();
                        imageController.setModel(new DefaultImageModel(Arrays.asList(files)));
                        navigationController.setModel(new DefaultNavigationModel(0, files.length));
                    }
                }
            });
            add(tb, BorderLayout.NORTH);
        }

    }

    public interface ImageModel {
        public File getImageAt(int index);
        public int size();
    }

    public interface ImageView {
        public void loadImageAt(int index);
        public void setDelegate(ImageViewDelegate delegate);
        public ImageViewDelegate getDelegate();
        public JComponent getView();
    }

    public interface ImageViewDelegate {
        public File imageAt(ImageView view, int index);
    }

    public interface ImageViewController {
        public ImageModel getModel();
        public ImageView getView();
        public void loadImageAt(int index);
    }

    public class DefaultImageModel implements ImageModel {

        private List<File> images;
        private int currentImage = -1;

        public DefaultImageModel(List<File> images) {
            this.images = new ArrayList<>(images);
        }

        @Override
        public File getImageAt(int index) {
            return images.get(index);
        }

        @Override
        public int size() {
            return images.size();
        }

    }

    public class DefaultImageController implements ImageViewController {

        private ImageView view;
        private ImageModel model;

        public DefaultImageController(ImageView view, ImageModel model) {
            Objects.requireNonNull(model, "Model can not be null");
            Objects.requireNonNull(view, "View can not be null");
            this.view = view;
            this.model = model;

            view.setDelegate(new ImageViewDelegate() {
                @Override
                public File imageAt(ImageView view, int index) {
                    return getModel().getImageAt(index);
                }
            });
        }

        public void setModel(ImageModel model) {
            Objects.requireNonNull(model, "Model can not be null");
            this.model = model;
        }

        @Override
        public ImageModel getModel() {
            return model;
        }

        @Override
        public ImageView getView() {
            return view;
        }

        @Override
        public void loadImageAt(int index) {
            getView().loadImageAt(index);
        }

    }

    public class DefaultImageViewPane extends JPanel implements ImageView {

        private ImageViewDelegate delegate;
        private BufferedImage img = null;

        public DefaultImageViewPane() {
        }

        @Override
        public Dimension getPreferredSize() {
            return img == null ? new Dimension(200, 200) : new Dimension(img.getWidth(), img.getHeight());
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            if (img != null) {
                Graphics2D g2d = (Graphics2D) g.create();
                int x = (getWidth() - img.getWidth()) / 2;
                int y = (getHeight() - img.getHeight()) / 2;
                g2d.drawImage(img, x, y, this);
                g2d.dispose();
            }
        }

        @Override
        public void setDelegate(ImageViewDelegate delegate) {
            this.delegate = delegate;
        }

        @Override
        public ImageViewDelegate getDelegate() {
            return delegate;
        }

        @Override
        public JComponent getView() {
            return this;
        }

        @Override
        public void loadImageAt(int index) {
            ImageViewDelegate delegate = getDelegate();
            if (delegate != null) {             
                img = null;
                File file = delegate.imageAt(this, index);
                if (file != null) {
                    try {
                        img = ImageIO.read(file);
                    } catch (IOException ex) {
                        ex.printStackTrace();
                    }
                }
                revalidate();
                repaint();
            }
        }
    }

    /**
     * *************************************************************************
     */
    public interface NavigationModel {
        public boolean next();
        public boolean previous();
        public int getIndex();
        public void addChangeListener(ChangeListener listener);
        public void removeChangeListener(ChangeListener listener);
        public boolean canNavigateForward();
        public boolean canNavigateBack();
    }

    public interface NavigationViewDelegate {
        public boolean next(NavigationView view);
        public boolean previous(NavigationView view);
        public boolean canNavigateForward();
        public boolean canNavigateBack();
    }

    public interface NavigationView {
        public void setDelegate(NavigationViewDelegate delegate);
        public NavigationViewDelegate getDelegate();
        public JComponent getView();
        public void stateChanged();
    }

    public interface NavigationContoller {
        public NavigationView getView();
        public NavigationModel getModel();
        public void addChangeListener(ChangeListener listener);
        public void removeChangeListener(ChangeListener listener);
    }

    public class DefaultNavigationController implements NavigationContoller {

        private NavigationView view;
        private NavigationModel model;

        private ChangeListener modelChangeListener;
        private final Set<ChangeListener> changeListeners;

        public DefaultNavigationController(NavigationView view, NavigationModel model) {
            Objects.requireNonNull(model, "Model can not be null");
            Objects.requireNonNull(view, "View can not be null");
            this.view = view;
            this.model = model;

            view.setDelegate(new NavigationViewDelegate() {
                @Override
                public boolean next(NavigationView view) {
                    return getModel().next();
                }

                @Override
                public boolean previous(NavigationView view) {
                    return getModel().previous();
                }

                @Override
                public boolean canNavigateForward() {
                    NavigationModel model = getModel();
                    return model.canNavigateForward();
                }

                @Override
                public boolean canNavigateBack() {
                    NavigationModel model = getModel();
                    return model.canNavigateBack();
                }
            });

            changeListeners = new HashSet<>(25);

            modelChangeListener = new ChangeListener() {
                @Override
                public void stateChanged(ChangeEvent e) {
                    getView().stateChanged();
                    fireStateChanged();
                }
            };
            this.model.addChangeListener(modelChangeListener);
            getView().stateChanged();
        }

        @Override
        public NavigationView getView() {
            return view;
        }

        @Override
        public NavigationModel getModel() {
            return model;
        }

        protected void setModel(NavigationModel model) {
            this.model.removeChangeListener(modelChangeListener);
            this.model = model;
            this.model.addChangeListener(modelChangeListener);
            getView().stateChanged();
            fireStateChanged();
        }

        @Override
        public void addChangeListener(ChangeListener listener) {
            changeListeners.add(listener);
        }

        @Override
        public void removeChangeListener(ChangeListener listener) {
            changeListeners.remove(listener);
        }

        protected void fireStateChanged() {
            ChangeEvent evt = new ChangeEvent(this);
            for (ChangeListener listener : changeListeners) {
                listener.stateChanged(evt);
            }
        }

    }

    public class DefaultNavigationModel implements NavigationModel {

        private final int minValue;
        private final int maxValue;
        private int currentIndex;
        private final Set<ChangeListener> changeListeners;

        public DefaultNavigationModel(int minValue, int maxValue) {
            this.maxValue = maxValue;
            this.minValue = minValue;
            currentIndex = minValue;

            changeListeners = new HashSet<>(25);
        }

        @Override
        public boolean next() {
            if (currentIndex + 1 < maxValue) {
                currentIndex++;
                fireStateChanged();
            }
            return canNavigateForward();
        }

        @Override
        public boolean previous() {
            if (currentIndex >= minValue) {
                currentIndex--;
                fireStateChanged();
            }
            return canNavigateBack();
        }

        @Override
        public int getIndex() {
            return currentIndex;
        }

        @Override
        public void addChangeListener(ChangeListener listener) {
            changeListeners.add(listener);
        }

        @Override
        public void removeChangeListener(ChangeListener listener) {
            changeListeners.remove(listener);
        }

        protected void fireStateChanged() {
            ChangeEvent evt = new ChangeEvent(this);
            for (ChangeListener listener : changeListeners) {
                listener.stateChanged(evt);
            }
        }

        @Override
        public boolean canNavigateForward() {
            return size() > 0 && currentIndex < maxValue - 1;
        }

        @Override
        public boolean canNavigateBack() {
            return size() > 0 && currentIndex > minValue;
        }

        public int size() {
            return maxValue - minValue;
        }

    }

    public class DefaultNavigationView extends JPanel implements NavigationView {

        private JButton nextButton;
        private JButton previousButton;

        private NavigationViewDelegate delegate;

        public DefaultNavigationView() {
            setLayout(new GridBagLayout());
            nextButton = new JButton(">");
            previousButton = new JButton("<");

            nextButton.setEnabled(false);
            previousButton.setEnabled(false);

            GridBagConstraints gbc = new GridBagConstraints();
            gbc.weightx = 1;
            gbc.anchor = GridBagConstraints.WEST;
            add(previousButton, gbc);
            gbc.anchor = GridBagConstraints.EAST;
            add(nextButton, gbc);

            nextButton.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    NavigationViewDelegate delegate = getDelegate();
                    if (delegate != null) {
                        nextButton.setEnabled(delegate.next(DefaultNavigationView.this));
                    }
                }
            });
            previousButton.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    NavigationViewDelegate delegate = getDelegate();
                    if (delegate != null) {
                        previousButton.setEnabled(delegate.previous(DefaultNavigationView.this));
                    }
                }
            });
        }

        @Override
        public NavigationViewDelegate getDelegate() {
            return delegate;
        }

        @Override
        public JComponent getView() {
            return this;
        }

        @Override
        public void setDelegate(NavigationViewDelegate delegate) {
            this.delegate = delegate;
            stateChanged();
        }

        @Override
        public void stateChanged() {
            nextButton.setEnabled(delegate != null && delegate.canNavigateForward());
            previousButton.setEnabled(delegate != null && delegate.canNavigateBack());
        }

    }
}

Answer 2

ArrayList<File> images = new ArrayList<>();
int selectedImageIndex =0;

public void selectFiles() {
    //you can call this method multiple times it wont matter
    //files selected at each time will be stored on the images arraylist
    JFileChooser chooser = new JFileChooser();
    chooser.setMultiSelectionEnabled(true);
    chooser.showOpenDialog(this);
    File[] files = chooser.getSelectedFiles();
    for (File file : files) {
        images.add(file);
    }
    startProgram(selectedImageIndex);
}

public void setImage(int index){

  if (index<images.size()) {
        File imageFile = images.get(index);
        selectedImageIndex = index;
        //read the file and set the image
   }else{
      System.out.println("no image found");
  }

}

public void goToNextImages(){
    ++selectedImageIndex;
    setImage(selectedImageIndex);
}

public void goToPreviousImage(){
    --selectedImageIndex;
    setImage(selectedImageIndex);
}

public void startProgram(int index){
    setImage(index);
}

使用JFileChooser上传多个图像

2 个答案:

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