java 生成图片缩略图_Java为图片生成缩略图

Java可以使用ImageIO类和BufferedImage类来生成图片缩略图。

以下是一个示例代码，它将加载指定的图片，将其缩小至指定的大小，并将其保存为新文件：

import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;

public class ImageThumbnail {
    public static void main(String[] args) {
        try {
            // Load the original image from file
            BufferedImage originalImage = ImageIO.read(new File("original.jpg"));
            
            // Calculate the new image size
            int thumbnailWidth = 100;
            int thumbnailHeight = (int) (((double) thumbnailWidth / (double) originalImage.getWidth()) * originalImage.getHeight());
            
            // Create a new, blank image of the appropriate size and type
            BufferedImage thumbnailImage = new BufferedImage(thumbnailWidth, thumbnailHeight, BufferedImage.TYPE_INT_RGB);
            
            // Scale the original image to the new size using Graphics2D
            Graphics2D g2d = thumbnailImage.createGraphics();
            g2d.drawImage(originalImage, 0, 0, thumbnailWidth, thumbnailHeight, null);
            g2d.dispose();
            
            // Save the scaled image to file
            ImageIO.write(thumbnailImage, "jpg", new File("thumbnail.jpg"));
        } catch (IOException ex) {
            System.err.println("Error generating thumbnail: " + ex.getMessage());
        }
    }
}

这个示例代码会将原始图片 "original.jpg" 缩小至 100 像素宽度，并将其高度按比例缩小。缩略图将保存为 "thumbnail.jpg"。