java实现图片的放大缩小(附完整源码)

以下是Java实现图片的放大缩小的完整源码：

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.RenderingHints;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JButton;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class ImageZoom extends JFrame implements ActionListener {
    private static final long serialVersionUID = 1L;
    private ImagePanel imagePanel;
    private JButton zoomInButton;
    private JButton zoomOutButton;
    private JButton openButton;
    private JButton saveButton;
    private BufferedImage image;
    private int zoomFactor = 100;

    public ImageZoom() {
        super("Image Zoom");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setPreferredSize(new Dimension(640, 480));
        imagePanel = new ImagePanel();
        add(imagePanel, BorderLayout.CENTER);
        zoomInButton = new JButton("Zoom In");
        zoomInButton.addActionListener(this);
        zoomOutButton = new JButton("Zoom Out");
        zoomOutButton.addActionListener(this);
        openButton = new JButton("Open");
        openButton.addActionListener(this);
        saveButton = new JButton("Save");
        saveButton.addActionListener(this);
        JPanel buttonPanel = new JPanel();
        buttonPanel.add(zoomInButton);
        buttonPanel.add(zoomOutButton);
        buttonPanel.add(openButton);
        buttonPanel.add(saveButton);
        buttonPanel.setBackground(Color.WHITE);
        add(buttonPanel, BorderLayout.SOUTH);
        pack();
        setLocationRelativeTo(null);
        setVisible(true);
    }

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

    @Override
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == zoomInButton) {
            zoomFactor += 10;
        } else if (e.getSource() == zoomOutButton) {
            zoomFactor -= 10;
        } else if (e.getSource() == openButton) {
            JFileChooser fileChooser = new JFileChooser();
            if (fileChooser.showOpenDialog(this) == JFileChooser.APPROVE_OPTION) {
                try {
                    image = ImageIO.read(fileChooser.getSelectedFile());
                    zoomFactor = 100;
                } catch (IOException ex) {
                    ex.printStackTrace();
                }
            }
        } else if (e.getSource() == saveButton) {
            JFileChooser fileChooser = new JFileChooser();
            if (fileChooser.showSaveDialog(this) == JFileChooser.APPROVE_OPTION) {
                try {
                    ImageIO.write(image, "png", fileChooser.getSelectedFile());
                } catch (IOException ex) {
                    ex.printStackTrace();
                }
            }
        }
        imagePanel.repaint();
    }

    private class ImagePanel extends JPanel {
        private static final long serialVersionUID = 1L;

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            if (image != null) {
                Graphics2D g2d = (Graphics2D) g.create();
                g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
                int width = image.getWidth() * zoomFactor / 100;
                int height = image.getHeight() * zoomFactor / 100;
                int x = (getWidth() - width) / 2;
                int y = (getHeight() - height) / 2;
                g2d.drawImage(image, x, y, width, height, null);
                g2d.dispose();
            }
        }
    }
}

实现思路：

1. 创建一个窗口，并在窗口中添加一个按钮面板和一个图片面板；
2. 实现按钮的点击事件，点击“放大”按钮时，将缩放系数增加10%，点击“缩小”按钮时，将缩放系数减少10%，点击“打开”按钮时，弹出文件选择对话框，选择图片文件后将图片加载到内存中，缩放系数设为100%，点击“保存”按钮时，弹出文件保存对话框，将图片保存为PNG格式；
3. 在图片面板的`paintComponent()`方法中绘制图片，使用`Graphics2D`对象进行绘制，设置渲染提示为双线性插值，根据缩放系数计算图片的宽度和高度，并居中显示。

实现细节：

1. 加载图片时，需要使用`ImageIO.read()`方法将图片文件读入内存；
2. 保存图片时，需要使用`ImageIO.write()`方法将图片保存到文件中；
3. 绘制图片时，需要使用`Graphics2D`对象进行绘制，并设置渲染提示为双线性插值，以获得更好的视觉效果；
4. 计算显示位置时，需要将图片居中显示。