这段代码将图像文件"original.jpg"的大小调整为宽度300像素，高度200像素，并将调整后的图像保存为"resized.jpg"。您可以根据需要修改输入和输出的文件路径和名称。

1. 方法一

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.*;public class ImageResize {public static byte[] resizeImage(byte[] imageData, int width, int height) throws IOException {ByteArrayInputStream bis = new ByteArrayInputStream(imageData);BufferedImage image = ImageIO.read(bis);Image resizedImage = image.getScaledInstance(width, height, Image.SCALE_SMOOTH);BufferedImage bufferedResizedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);bufferedResizedImage.getGraphics().drawImage(resizedImage, 0, 0, null);ByteArrayOutputStream bos = new ByteArrayOutputStream();ImageIO.write(bufferedResizedImage, "jpg", bos);byte[] resizedImageData = bos.toByteArray();bis.close();bos.close();return resizedImageData;}public static void main(String[] args) {try {byte[] originalImageData = Files.readAllBytes(new File("original.jpg").toPath());byte[] resizedImageData = resizeImage(originalImageData, 300, 200);Files.write(new File("resized.jpg").toPath(), resizedImageData);System.out.println("图片调整大小成功！");} catch (IOException e) {System.out.println("图片调整大小失败: " + e.getMessage());}}
}

2. 方法二

public static byte[] resizeImage(byte[] finalImage, int width, int height) {try {BufferedImage img = ImageIO.read(new ByteArrayInputStream(imageByte));//创建新图片BufferedImage image = new BufferedImage(newWidth, newHeight, BufferedImage.TYPE_INT_RGB);Graphics2D g2d = image.createGraphics();g2d.setColor(Color.WHITE);g2d.fillRect(0, 0, newWidth, newHeight);//g2d.drawImage(img, (newWidth - img.getWidth()) / 2, (newHeight - img.getHeight()) / 2, null);g2d.drawImage(img.getScaledInstance(newWidth, newHeight, Image.SCALE_SMOOTH), 0, 0, null);g2d.dispose();ByteArrayOutputStream byteArrayOut = new ByteArrayOutputStream();ImageIO.write(image, "jpg", byteArrayOut);finalImage = byteArrayOut.toByteArray();} catch (IOException e) {e.printStackTrace();}
}