<dependency> <groupId>net.coobird</groupId> <artifactId>thumbnailator</artifactId> <version>0.4.8</version></dependency>Thumbnails.of("images/a380_1280x1024.jpg").size(200, 300).toFile("c:/a380_200x300.jpg");
2、按照比例进行缩放
Thumbnails.of("images/a380_1280x1024.jpg").scale(0.25f).toFile("c:/a380_25%.jpg");
3、不按照比例，指定大小进行缩放
//keepAspectRatio(false) 默认是按照比例缩放的
Thumbnails.of("images/a380_1280x1024.jpg").size(200,200).keepAspectRatio(false).toFile("c:/a380_200x200.jpg");
4、旋转
Thumbnails.of("images/a380_1280x1024.jpg").size(1280,1024).watermark(Positions.BOTTOM_RIGHT,ImageIO.read(newFile("images/watermark.png")),0.5f).outputQuality(0.8f).toFile("c:/a380_watermark_bottom_right.jpg");
6、裁剪
//图片中心400*400的区域
Thumbnails.of("images/a380_1280x1024.jpg").sourceRegion(Positions.CENTER,400,400).size(200,200).keepAspectRatio(false).toFile("c:/a380_region_center.jpg");
Thumbnails.of("images/a380_1280x1024.jpg").size(1280,1024).outputFormat("png").toFile("c:/a380_1280x1024.png");
OutputStream os = new FileOutputStream("c:/a380_1280x1024_OutputStream.png");
Thumbnails.of("images/a380_1280x1024.jpg").size(1280,1024).toOutputStream(os);
9、输出到BufferedImage
//asBufferedImage()返回BufferedImage
BufferedImage thumbnail=Thumbnails.of("images/a380_1280x1024.jpg").size(1280,1024).asBufferedImage();
ImageIO.write(thumbnail,"jpg",newFile("c:/a380_1280x1024_BufferedImage.jpg"));
google使用的开源的工具类Thumbnailator图像处理
原文：https://www.cnblogs.com/grasp/p/9689669.html