浏览图像文件并使用Java Swing显示它

我的问题是，在单击“ 浏览”按钮后，它会显示要选择的目录中的所有文件，然后所选图像将正确显示在GUI中。 但是当我第二次单击“浏览”按钮时，它仅显示旧图像而不是显示新图像。 请帮帮我。

作为参考，我上传了UI。

package GUI; import java.awt.BorderLayout; import java.awt.EventQueue; import java.awt.Graphics2D; import javax.imageio.ImageIO; import javax.swing.ImageIcon; import javax.swing.JFileChooser; import javax.swing.JFrame; import javax.swing.JOptionPane; import javax.swing.JPanel; import javax.swing.border.EmptyBorder; import javax.swing.JLabel; import javax.swing.JButton; import java.awt.event.ActionListener; import java.awt.event.ActionEvent; import java.awt.image.BufferedImage; import java.io.File; import java.io.IOException; import java.util.logging.Level; import java.util.logging.Logger; import javax.swing.GroupLayout; import javax.swing.GroupLayout.Alignment; @SuppressWarnings("serial") public class MainAppFrame extends JFrame { private JPanel contentPane; File targetFile; BufferedImage targetImg; public JPanel panel,panel_1; private static final int baseSize = 128; private static final String basePath =![enter image description here][1] "C:\\Documents and Settings\\Administrator\\Desktop\\Images"; /** * Launch the application. */ public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { public void run() { try { MainAppFrame frame = new MainAppFrame(); frame.setVisible(true); frame.setResizable(false); } catch (Exception e) { e.printStackTrace(); } } }); } /** * Create the frame. */ public MainAppFrame() { setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); setBounds(100, 100, 550, 400); contentPane = new JPanel(); contentPane.setBorder(new EmptyBorder(5, 5, 5, 5)); setContentPane(contentPane); contentPane.setLayout(new BorderLayout(0, 0)); panel = new JPanel(); panel.setBorder(new javax.swing.border.LineBorder(new java.awt.Color(0, 0, 0), 1, true)); contentPane.add(panel, BorderLayout.WEST); JButton btnBrowse = new JButton("Browse"); btnBrowse.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { browseButtonActionPerformed(e); } }); JLabel lblSelectTargetPicture = new JLabel("Select target picture.."); JButton btnDetect = new JButton("Detect"); btnDetect.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { } }); JButton btnAddDigit = new JButton("Add Digit"); btnAddDigit.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { } }); JButton button = new JButton("Recognize"); button.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { } }); panel_1 = new JPanel(); panel_1.setBorder(new javax.swing.border.LineBorder(new java.awt.Color(0, 0, 0), 1, true)); GroupLayout gl_panel = new GroupLayout(panel); gl_panel.setHorizontalGroup( gl_panel.createParallelGroup(Alignment.LEADING) .addGroup(gl_panel.createSequentialGroup() .addGap(6) .addGroup(gl_panel.createParallelGroup(Alignment.LEADING) .addGroup(gl_panel.createSequentialGroup() .addComponent(lblSelectTargetPicture) .addGap(6) .addComponent(btnBrowse)) .addGroup(gl_panel.createSequentialGroup() .addGap(10) .addComponent(btnDetect) .addGap(18) .addComponent(btnAddDigit)))) .addGroup(gl_panel.createSequentialGroup() .addGap(50) .addComponent(button)) .addGroup(gl_panel.createSequentialGroup() .addContainerGap() .addComponent(panel_1, GroupLayout.PREFERRED_SIZE, 182, GroupLayout.PREFERRED_SIZE)) ); gl_panel.setVerticalGroup( gl_panel.createParallelGroup(Alignment.LEADING) .addGroup(gl_panel.createSequentialGroup() .addGroup(gl_panel.createParallelGroup(Alignment.LEADING) .addGroup(gl_panel.createSequentialGroup() .addGap(7) .addComponent(lblSelectTargetPicture)) .addGroup(gl_panel.createSequentialGroup() .addGap(3) .addComponent(btnBrowse))) .addGap(18) .addComponent(panel_1, GroupLayout.PREFERRED_SIZE, 199, GroupLayout.PREFERRED_SIZE) .addGap(22) .addGroup(gl_panel.createParallelGroup(Alignment.BASELINE) .addComponent(btnDetect) .addComponent(btnAddDigit)) .addGap(18) .addComponent(button) .addContainerGap()) ); panel.setLayout(gl_panel); } public BufferedImage rescale(BufferedImage originalImage) { BufferedImage resizedImage = new BufferedImage(baseSize, baseSize, BufferedImage.TYPE_INT_RGB); Graphics2D g = resizedImage.createGraphics(); g.drawImage(originalImage, 0, 0, baseSize, baseSize, null); g.dispose(); return resizedImage; } public void setTarget(File reference) { try { targetFile = reference; targetImg = rescale(ImageIO.read(reference)); } catch (IOException ex) { Logger.getLogger(MainAppFrame.class.getName()).log(Level.SEVERE, null, ex); } panel_1.setLayout(new BorderLayout(0, 0)); panel_1.add(new JLabel(new ImageIcon(targetImg))); setVisible(true); } private void browseButtonActionPerformed(java.awt.event.ActionEvent evt) { JFileChooser fc = new JFileChooser(basePath); fc.setFileFilter(new JPEGImageFileFilter()); int res = fc.showOpenDialog(null); // We have an image! try { if (res == JFileChooser.APPROVE_OPTION) { File file = fc.getSelectedFile(); setTarget(file); } // Oops! else { JOptionPane.showMessageDialog(null, "You must select one image to be the reference.", "Aborting...", JOptionPane.WARNING_MESSAGE); } } catch (Exception iOException) { } } } //JPEGImageFileFilter.java package GUI; import java.io.File; import javax.swing.filechooser.FileFilter; /* * This class implements a generic file name filter that allows the listing/selection * of JPEG files. */ public class JPEGImageFileFilter extends FileFilter implements java.io.FileFilter { public boolean accept(File f) { if (f.getName().toLowerCase().endsWith(".jpeg")) return true; if (f.getName().toLowerCase().endsWith(".jpg")) return true; if(f.isDirectory())return true; return false; } public String getDescription() { return "JPEG files"; } } 

Answer 1

每次选择新图像时，您都会不必要地创建组件，并在此处出错：

 public void setTarget(File reference) { //.... panel_1.setLayout(new BorderLayout(0, 0)); panel_1.add(new JLabel(new ImageIcon(targetImg))); setVisible(true); 

相反，我会建议您在选择任何文件/图像之前从一开始就创建所有这些组件，然后在此方法中，从Image创建一个ImageIcon，然后只需使用此图标设置Icon已经存在的JLabel而不是新的JLabel。 只需调用myLabel.setIcon(new ImageIcon(targetImg));即可完成此操作myLabel.setIcon(new ImageIcon(targetImg));

Answer 2

使用ImageViewer.setImage(Image)等方法创建ImageViewer ，在JLabel显示图像。

图像浏览器

 import java.awt.*; import java.awt.event.*; import java.awt.image.BufferedImage; import javax.swing.*; import javax.swing.border.EmptyBorder; import java.util.Random; public class ImageViewer { JPanel gui; /** Displays the image. */ JLabel imageCanvas; /** Set the image as icon of the image canvas (display it). */ public void setImage(Image image) { imageCanvas.setIcon(new ImageIcon(image)); } public void initComponents() { if (gui==null) { gui = new JPanel(new BorderLayout()); gui.setBorder(new EmptyBorder(5,5,5,5)); imageCanvas = new JLabel(); JPanel imageCenter = new JPanel(new GridBagLayout()); imageCenter.add(imageCanvas); JScrollPane imageScroll = new JScrollPane(imageCenter); imageScroll.setPreferredSize(new Dimension(300,100)); gui.add(imageScroll, BorderLayout.CENTER); } } public Container getGui() { initComponents(); return gui; } public static Image getRandomImage(Random random) { int w = 100 + random.nextInt(400); int h = 50 + random.nextInt(200); BufferedImage bi = new BufferedImage( w,h,BufferedImage.TYPE_INT_RGB); return bi; } public static void main(String[] args) throws Exception { Runnable r = new Runnable() { @Override public void run() { JFrame f = new JFrame("Image Viewer"); // TODO Fix kludge to kill the Timer f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); final ImageViewer viewer = new ImageViewer(); f.setContentPane(viewer.getGui()); f.pack(); f.setLocationByPlatform(true); f.setVisible(true); ActionListener animate = new ActionListener() { Random random = new Random(); @Override public void actionPerformed(ActionEvent arg0) { viewer.setImage(getRandomImage(random)); } }; Timer timer = new Timer(1500,animate); timer.start(); } }; SwingUtilities.invokeLater(r); } } 

Answer 3

我修改了你的代码，希望它能满足你的要求。 我使用MigLayout（它是一个布局管理器）来安排组件。

 import java.awt.BorderLayout; import java.awt.Color; import java.awt.Graphics2D; 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.logging.Level; import java.util.logging.Logger; import javax.imageio.ImageIO; import javax.swing.BoxLayout; import javax.swing.ImageIcon; import javax.swing.JButton; import javax.swing.JFileChooser; import javax.swing.JFrame; import javax.swing.JLabel; import javax.swing.JOptionPane; import javax.swing.JPanel; import javax.swing.SwingUtilities; import net.miginfocom.swing.MigLayout; public class MyFileChooser { JFrame frame; JPanel panel; JButton btnBrowse; JButton change; JLabel imglabel; File targetFile; BufferedImage targetImg; private static final int baseSize = 128; private static final String basePath ="/images/fimage"; JPanel panel_1; ImageIcon icon; public MyFileChooser() { // TODO Auto-generated constructor stub frame =new JFrame(); frame.setLayout(new MigLayout()); frame.setSize(300, 300); frame.setVisible(true); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); panel=new JPanel(new MigLayout()); panel_1 = new JPanel(); panel_1.setBorder(new javax.swing.border.LineBorder(new java.awt.Color(5, 5, 5), 1, true)); panel_1.setBackground(Color.pink); btnBrowse=new JButton("browse"); btnBrowse.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { browseButtonActionPerformed(e); } }); change=new JButton("Delete"); change.addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { // TODO Auto-generated method stub changeButtonActionPerformed(e); } private void changeButtonActionPerformed(ActionEvent e) { // TODO Auto-generated method stub imglabel.revalidate(); //ADD THIS AS WELL imglabel.repaint(); //ADD THIS AS WELL imglabel.setIcon(null); System.out.println("delete button activated"); } }); imglabel=new JLabel("Image"); imglabel.setSize(100, 100); imglabel.setBackground(Color.yellow); frame.add(panel_1,"span,pushx,pushy,growx,growy"); frame.add(btnBrowse); frame.add(change,""); //frame.pack(); } protected void browseButtonActionPerformed(ActionEvent e) { JFileChooser fc = new JFileChooser(basePath); fc.setFileFilter(new JPEGImageFileFilter()); int res = fc.showOpenDialog(null); // We have an image! try { if (res == JFileChooser.APPROVE_OPTION) { File file = fc.getSelectedFile(); imglabel.setIcon(null); setTarget(file); } // Oops! else { JOptionPane.showMessageDialog(null, "You must select one image to be the reference.", "Aborting...", JOptionPane.WARNING_MESSAGE); } } catch (Exception iOException) { } } public BufferedImage rescale(BufferedImage originalImage) { BufferedImage resizedImage = new BufferedImage(baseSize, baseSize, BufferedImage.TYPE_INT_RGB); Graphics2D g = resizedImage.createGraphics(); g.drawImage(originalImage, 0, 0, baseSize, baseSize, null); g.dispose(); return resizedImage; } public void setTarget(File reference) { try { targetFile = reference; targetImg = rescale(ImageIO.read(reference)); } catch (IOException ex) { // Logger.getLogger(MainAppFrame.class.getName()).log(Level.SEVERE, null, ex); } panel_1.setLayout(new BorderLayout(0, 0)); icon=new ImageIcon(targetImg); imglabel=new JLabel(icon); panel_1.add(imglabel); frame.setVisible(true); } public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { @Override public void run() { // TODO Auto-generated method stub new MyFileChooser(); } }); } 

}

JPEGImageFileFilter类，您可以将此类保持在同一个pakage中

 import java.io.File; import javax.swing.filechooser.FileFilter; public class JPEGImageFileFilter extends FileFilter implements FileFilter { public boolean accept(File f) { if (f.getName().toLowerCase().endsWith(".jpeg")) return true; if (f.getName().toLowerCase().endsWith(".jpg")) return true; if(f.isDirectory())return true; return false; } public String getDescription() { return "JPEG files"; } }