在Java中使用Swing显示图像

2019年7月28日 202次阅读

我一直在抓取Oracle和Stack Overflow试图找到我的问题的解决方案,但我还没有设法找到我要找的东西.

下面我有两个类,目前需要做的所有程序都是允许用户使用JFileChooser打开一个图像文件并在GUI中显示(所以稍后可以对它进行一些图像处理)

我已经测试了代码执行,我知道ImageGUI类中的变量img正在初始化为我想要的第99行图片.我的问题是在我打包之前让图像显示在GUI中;它.

我错过了什么？

 public class ImageEditLaunch {

public static void main(String[] args) {
    ImageEditEngine program = new ImageEditEngine();

}

}

import java.awt.image.BufferedImage;
import java.io.File;

import javax.imageio.ImageIO;
import javax.swing.ImageIcon;

public class ImageEditEngine {

    private static int[][][] originalImage;
    private static BufferedImage originalImageBuffer;

    public ImageEditEngine() {
        originalImage = new int[0][0][0];
        ImageGUI gui = new ImageGUI();
        gui.setVisible(true);
    }

    public static ImageIcon openImage(String filepath){
        try{

        File f = new File(filepath);
        BufferedImage image = ImageIO.read(f);
        originalImageBuffer = image;
        ImageIcon icon = new ImageIcon(image);
        return icon;

        }
        catch(Exception e){
            e.printStackTrace();
            return new ImageIcon();
        }

    }
}

import java.awt.Dimension;
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import javax.swing.ImageIcon;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.UIManager;

public class ImageGUI extends JFrame implements ActionListener{

    private JFrame window;

    private JMenuItem mOpenFile;
    private JMenuItem mSaveFile;
    private JMenuItem mExitCommand;

    private JMenuBar parentBar;
    private JMenu fileMenu;
    private JMenu commandMenu;

    private JPanel mainPanel;

    public ImageIcon img;

    private JLabel mLabel;

    public ImageGUI(){
        super();
        try{
        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        }
        catch(Exception e){
            e.printStackTrace();
        }
        //setup CommandMenu
        commandMenu = makeMenu("Command", 'C');

        //setup FileMenu
        fileMenu  = makeMenu("File", 'F');
        mOpenFile     = makeMenuItem(fileMenu, "Open...", 'O');
        mSaveFile     = makeMenuItem(fileMenu, "Save...", 'S');
        mExitCommand  = makeMenuItem(fileMenu, "Exit", 'X');

        //setup parentBar
        parentBar = new JMenuBar();
        parentBar.add(fileMenu);
        parentBar.add(commandMenu);

        //main panel
        mainPanel = new JPanel(new BorderLayout());
        mLabel = new JLabel();
        mainPanel.add(mLabel, BorderLayout.CENTER);
        setJMenuBar(parentBar);
        setSize(new Dimension(400, 300));

    }

    protected JMenuItem makeMenuItem(JMenu menu, String name, char mnemonic){
        JMenuItem m = new JMenuItem(name, (int) mnemonic);
        m.addActionListener(this);
        menu.add(m);
        return m;
    }

    protected JMenu makeMenu(String name, char mnemonic){
        JMenu menu = new JMenu(name);
        menu.setMnemonic(mnemonic);
        return menu;
    }


    @Override
    public void actionPerformed(ActionEvent arg0) {
        if(arg0.getSource()==mOpenFile){
            String path = null;

            JFileChooser jfc = new JFileChooser();
            jfc.setCurrentDirectory(new File("."));

            int result = jfc.showOpenDialog(this);

            if (result == JFileChooser.APPROVE_OPTION) {
                File file = jfc.getSelectedFile();
                path = file.getAbsolutePath();
            }

            img=ImageEditEngine.openImage(path);
            mLabel= new JLabel(img);
            mLabel.setVisible(true);
            this.repaint();
            pack();

        }

    }
}

之后的mLabel上的toString()的值：

mLabel = new JLabel(img);

如下

javax.swing.JLabel[,0,0,0x0,invalid,alignmentX=0.0,alignmentY=0.0,
border=,flags=8388608,maximumSize=,minimumSize=,preferredSize=,
defaultIcon=javax.swing.ImageIcon@2bd58ce,disabledIcon=,
horizontalAlignment=CENTER,horizontalTextPosition=TRAILING,
iconTextGap=4,labelFor=,text=,verticalAlignment=CENTER,
verticalTextPosition=CENTER]

最佳答案 根本问题在于面板从未添加到框架中.代码还有许多其他问题,其中一些我修复了(只是删除了它的整个部分),其他我调整过的.下面显示的代码还有其他问题需要修复(我在懒惰编码中引入了其中一个或两个 – 但它们并不致命).

话虽如此,这段代码现在有效.仔细查看它的提示.请注意,它是一个热链接到图像的MCVE,因此应该很容易测试.

import java.awt.image.*;
import java.awt.*;
import javax.swing.*;
import javax.imageio.*;
import java.net.URL;

public class ImageEditEngine {

    private static int[][][] originalImage;
    private static BufferedImage originalImageBuffer;

    public ImageEditEngine() {
        originalImage = new int[0][0][0];
        ImageGUI gui = new ImageGUI();
        gui.setVisible(true);
    }

    public static ImageIcon openImage(){
        try{
            URL url = new URL("https://i.stack.imgur.com/OVOg3.jpg");

            BufferedImage image = ImageIO.read(url);
            originalImageBuffer = image;
            ImageIcon icon = new ImageIcon(image);
            return icon;

        }
        catch(Exception e){
            e.printStackTrace();
            return new ImageIcon();
        }
    }

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


class ImageGUI extends JFrame {

    private JPanel mainPanel;

    public ImageIcon img;

    private JLabel mLabel;

    public ImageGUI(){
        super();
        setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        try{
            UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
        }
        catch(Exception e){
            e.printStackTrace();
        }
        //main panel
        mainPanel = new JPanel(new BorderLayout());
        mLabel = new JLabel();
        mainPanel.add(mLabel, BorderLayout.CENTER);

        add(mainPanel);

        setSize(new Dimension(400, 300));

        img=ImageEditEngine.openImage();
        mLabel.setIcon(img);
        mLabel.setVisible(true);
        this.repaint();
        pack();
    }
}
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