Question

我有问题。我不知道如何通过单击JButton来显示图像。

我有一个可以显示和隐藏图像的课程：

/**
 * 
 */
package com.samples;

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.WindowConstants;

/**
 * @author
 *
 */
public class New2 extends JFrame implements ActionListener {

    private static String SHOW_ACTION = "show";
    private static String HIDE_ACTION = "hide";

    private Image image = null;
    private boolean showImage = false;

    public New2(String filename) {
        setTitle("MyWindow");
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setSize(800, 600);

        this.image = new ImageIcon("..//src/img/Ster.png").getImage();

        Container container = getContentPane();
        container.setLayout(new BorderLayout());
        container.add(createControls(), BorderLayout.SOUTH);
    }

    private JPanel createControls() {
        JButton showButton = new JButton("Show");
        showButton.addActionListener(this);
        showButton.setActionCommand(SHOW_ACTION);

        JButton hideButton = new JButton("Hide");
        hideButton.addActionListener(this);
        hideButton.setActionCommand(HIDE_ACTION);

        JPanel panel = new JPanel();
        panel.setLayout(new FlowLayout(FlowLayout.CENTER));

        panel.add(showButton);
        panel.add(hideButton);

        return panel;
    }

    @Override
    public void paint(Graphics g) {
        super.paint(g);

        if (showImage) {
            g.drawImage(image, 100, 200, image.getWidth(null), image.getHeight(null), null);
        }
    }

    @Override
    public void actionPerformed(ActionEvent event) {
        String actionCommand = event.getActionCommand();

        if (SHOW_ACTION.equals(actionCommand)) {
            showImage = true;
        } else if (HIDE_ACTION.equals(actionCommand)) {
            showImage = false;
        }

        repaint();
    }

    /**
     * @param args
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                New2 frame = new New2("resources/image.jpg");
                frame.setVisible(true);
            }
        });
    }
}

我正在使用MVC所以我想在控制器的地图中使用JButton的代码，但我不知道如何做到这一点。

package View;

import java.awt.Color;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Image;
import java.awt.event.ActionListener;

import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JButton;
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 Controller.HomeController;
import Controller.KeeperController;

public class Selectie extends JFrame{

    private JLabel label, label1, label2;
    private JButton keeper;
    private JPanel panel;
    private Container window = getContentPane();
    private KeeperController controller;


    public Selectie()
    {
        initGUI();

    }

    public void initGUI()
    {
        setLayout(null);
        setTitle();
        setSize(800,600);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        label = new JLabel();       
        label.setBounds(0, 0, 266, 800);
        label.setBackground(Color.RED);
        label.setOpaque(true);
        window.add(label);

        label1 = new JLabel();
        label1.setBounds(266, 0, 266, 800);
        label1.setBackground(Color.BLACK);
        label1.setOpaque(true);
        window.add(label1);

        label2 = new JLabel();
        label2.setBounds(532, 0, 266, 800);
        label2.setBackground(Color.RED);
        label2.setOpaque(true);
        window.add(label2);

        keeper = new JButton("1. "+""+" Kenneth Vermeer");
        keeper.setBounds(60, 500, 200, 25);
        keeper.setFocusable(false);
        keeper.setBorderPainted(false);
        keeper.setContentAreaFilled(false);
        keeper.setFont(new Font("Arial",Font.PLAIN,17));
        label.add(keeper);

        }

}

按钮管理员需要在点击图像时显示图像。

Answer 1

同样地说，其他人总是使用JLabel来显示图像。这样，很容易在需要时添加/删除它们，而不是绘画。此外，在您的代码中，您覆盖paint(...)，对于Swing，如果所述组件中有paintComponent(...)，我们希望覆盖相应JComponent的{{1}}方法。

在这里试试这段代码，我把控制器部分分开，你可能会对如何做事有所了解：

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.Icon;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.WindowConstants;

/**
 * @author
 *
 */
public class New2 extends JFrame
{

    private static String SHOW_ACTION = "show";
    private static String HIDE_ACTION = "hide";

    public New2(String filename) 
    {
        setTitle("MyWindow");
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setSize(800, 600);        

        Container container = getContentPane();
        container.setLayout(new BorderLayout());
        container.add(createControls(), BorderLayout.CENTER);
    }

    private JPanel createControls() 
    {
        JButton showButton = new JButton("Show");        
        showButton.setActionCommand(SHOW_ACTION);

        JButton hideButton = new JButton("Hide");        
        hideButton.setActionCommand(HIDE_ACTION);

        JLabel imageLabel = new JLabel();

        New2Controller n2c = new New2Controller(showButton
                                                                        , hideButton, imageLabel);
        showButton.addActionListener(n2c);          
        hideButton.addActionListener(n2c);  

        JPanel panel = new JPanel();
        panel.setLayout(new FlowLayout(FlowLayout.CENTER));

        panel.add(imageLabel);
        panel.add(showButton);
        panel.add(hideButton);

        return panel;
    }

    /**
     * @param args
     */
    public static void main(String[] args) 
    {
        EventQueue.invokeLater(new Runnable() 
        {
            @Override
            public void run() 
            {
                New2 frame = new New2("/img/image.jpg");
                frame.setVisible(true);
            }
        });
    }
}

class New2Controller implements ActionListener
{
    private JButton showButton;
    private JButton hideButton;
    private JLabel imageLabel;
    private static String SHOW_ACTION = "show";
    private static String HIDE_ACTION = "hide";
    private Icon infoIcon = UIManager.getIcon("OptionPane.informationIcon");

    public New2Controller(JButton show, JButton hide, JLabel label)
    {
        showButton = show;
        hideButton = hide;
        imageLabel = label;
    }

    public void actionPerformed(ActionEvent event)
    {
        String actionCommand = event.getActionCommand();

        if (SHOW_ACTION.equals(actionCommand)) 
        {
            SwingUtilities.invokeLater(new Runnable()
            {
                public void run()
                {                       
                    imageLabel.setIcon(infoIcon);
                }
            });
        } 
        else if (HIDE_ACTION.equals(actionCommand)) 
        {
            imageLabel.setIcon(null);
        }
    }
}

此代码代表您使用ImageIO和URL，

阅读的方式

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JLabel;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.WindowConstants;

import javax.imageio.ImageIO;

/**
 * @author
 *
 */
public class New2 extends JFrame
{
    private static String SHOW_ACTION = "show";
    private static String HIDE_ACTION = "hide";

    public New2(String filename) 
    {
        setTitle("MyWindow");
        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        setSize(800, 600);        

        Container container = getContentPane();
        container.setLayout(new BorderLayout());
        container.add(createControls(), BorderLayout.CENTER);
    }

    private JPanel createControls() 
    {
        JButton showButton = new JButton("Show");        
        showButton.setActionCommand(SHOW_ACTION);

        JButton hideButton = new JButton("Hide");        
        hideButton.setActionCommand(HIDE_ACTION);

        JLabel imageLabel = new JLabel();

        New2Controller n2c = new New2Controller(showButton
                                      , hideButton, imageLabel);
        showButton.addActionListener(n2c);          
        hideButton.addActionListener(n2c);

        JPanel panel = new JPanel();
        panel.setLayout(new FlowLayout(FlowLayout.CENTER));

        panel.add(imageLabel);
        panel.add(showButton);
        panel.add(hideButton);

        return panel;
    }

    /**
     * @param args
     */
    public static void main(String[] args) 
    {
        EventQueue.invokeLater(new Runnable() 
        {
            @Override
            public void run() 
            {
                New2 frame = new New2("/img/image.jpg");  
                frame.setVisible(true);
            }
        });
    }
}

class New2Controller implements ActionListener
{
    private JButton showButton;
    private JButton hideButton;
    private JLabel imageLabel;
    private Image image;
    private ImageIcon imageIcon;
    private static String SHOW_ACTION = "show";
    private static String HIDE_ACTION = "hide";

    public New2Controller(JButton show, JButton hide, JLabel label)
    {
        showButton = show;
        hideButton = hide;
        imageLabel = label;
        try
        {
            image = ImageIO.read(getClass().getResource("/img/caIcon.png"));
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
        imageIcon = new ImageIcon(image);
    }

    public void actionPerformed(ActionEvent event)
    {
        String actionCommand = event.getActionCommand();

        if (SHOW_ACTION.equals(actionCommand)) 
        {
            SwingUtilities.invokeLater(new Runnable()
            {
                public void run()
                {                       
                    imageLabel.setIcon(imageIcon );
                }
            });
        } 
        else if (HIDE_ACTION.equals(actionCommand)) 
        {
            imageLabel.setIcon(null);
        }
    }
}

此外，当您使用BorderLayout时，永远不要对BorderLayout使用NORTH，EAST，WEST和SOUTH。它们已分别替换为PAGE_START，LINE_START，LINE_END和PAGE_END。

BorderLayout对象有五个区域。这些区域由BorderLayout常量指定：

PAGE_START
PAGE_END
LINESTART
LINE_END
CENTER

版本说明：在JDK 1.4版之前，各个区域的首选名称不同，从指南针的点（例如，顶部区域的BorderLayout.NORTH）到更高版本的我们在示例中使用的常量。我们的示例使用的常量是首选，因为它们是标准的，并使程序能够适应具有不同方向的语言。

目录结构：

                                Your Project
                                |          | 
                              classes     src 
                              |     |
                             img  *.class(or package Folder)

现在使用getClass().getResource("/img/star.png");

Answer 2

1）使用JLabel#setIcon()代替将图片绘制为JFrame

的背景

2）在class Selectie

中创建方法

private void setIconToLabel (Icon icon){

     myDesiredLabel.setIcon(icon);
}

3）不要为另一个使用JFrame instaed的图像创建新的CardLayout

Answer 3

您只需添加JLabel即可在其上显示图像。在此之后，您可以根据条件设置可见的JLabel。

单击JButton显示图像

3 个答案: