java 批量修改图片大小

以下是使用Java自带类进行批量修改图片大小的方法：

1. 使用ImageIO读取图片，获取图片的宽度和高度。
2. 创建一个BufferedImage对象，将原始图片绘制到该对象上。
3. 创建新的BufferedImage对象，设置新的宽度和高度。
4. 将原始图片绘制到新的BufferedImage对象上，并将其保存为新的图片文件。

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

public class ImageResizer {
    public static void resize(String inputImagePath, String outputImagePath, int scaledWidth, int scaledHeight)
            throws IOException {
        // Read the source image
        File inputFile = new File(inputImagePath);
        BufferedImage inputImage = ImageIO.read(inputFile);

        // Create the output image
        BufferedImage outputImage = new BufferedImage(scaledWidth, scaledHeight, inputImage.getType());

        // Scale the input image to the output image
        Graphics2D g2d = outputImage.createGraphics();
        g2d.drawImage(inputImage, 0, 0, scaledWidth, scaledHeight, null);
        g2d.dispose();

        // Save the scaled image as a JPEG
        File outputFile = new File(outputImagePath);
        ImageIO.write(outputImage, "jpg", outputFile);
    }
}

调用上述方法，可以批量修改图片大小：

public class BatchImageResizer {
    public static void main(String[] args) {
        String inputDir = "input";
        String outputDir = "output";
        int scaledWidth = 800;
        int scaledHeight = 600;

        File inputFolder = new File(inputDir);
        File[] inputFiles = inputFolder.listFiles();

        for (File inputFile : inputFiles) {
            String inputFileName = inputFile.getName();
            String outputFileName = inputFileName.substring(0, inputFileName.lastIndexOf(".")) + ".jpg";
            String inputFilePath = inputDir + File.separator + inputFileName;
            String outputFilePath = outputDir + File.separator + outputFileName;

            try {
                ImageResizer.resize(inputFilePath, outputFilePath, scaledWidth, scaledHeight);
            } catch (IOException ex) {
                System.out.println("Error resizing the image: " + inputFileName);
                ex.printStackTrace();
            }
        }
    }
}