浏览图像文件并使用 Java Swing 显示它 [英] Browse for image file and display it using Java Swing
本文介绍了浏览图像文件并使用 Java Swing 显示它的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我的问题是，单击 Browse 按钮后，它会显示要选择的目录中的所有文件，然后选择的图像在 GUI 中正确显示.但是当我点击浏览按钮时第二次，它只显示旧图像而不显示新图像.请帮我解决这个问题.
My problem here is, after clicking Browse button it displays all files in a directory to choose, then the chosen image is displayed in GUI correctly. But When i click Browse button for the second time, it shows the old image only instead of showing the new one. Please help me in this.
作为参考，我上传了用户界面.
For reference, i uploaded the 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 =
"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";
}
}
推荐答案
每次选择新图像时，您都会在此处创建不必要的组件并出错:
Each time a new image is selected, you're creating components unnecessarily and in error here:
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，从图像创建一个 ImageIcon，然后只需使用此 Icon 来设置已存在的 JLabel 的 Icon 而不是新的 JLabel.这只需调用 myLabel.setIcon(new ImageIcon(targetImg));
Instead I would recommend that you have all these components created from the get-go, before any file/image has been selected, and then in this method, create an ImageIcon from the Image, and then simply use this Icon to set the Icon of an already existng JLabel rather than a new JLabel. This is done simply by calling myLabel.setIcon(new ImageIcon(targetImg));
这篇关于浏览图像文件并使用 Java Swing 显示它的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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