google使用的开源的工具类Thumbnailator图像处理

maven依赖

<dependency>

    <groupId>net.coobird</groupId>

    <artifactId>thumbnailator</artifactId>

    <version>0.4.8</version>

</dependency>

使用接口例子 https://github.com/coobird/thumbnailator/wiki/Examples

1、指定大小进行缩放

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

//rotate(角度),正数：顺时针负数：逆时针

Thumbnails.of("images/a380_1280x1024.jpg").size(1280,1024).rotate(90).toFile("c:/a380_rotate+90.jpg");

5、水印

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");

7、转化图像格式

Thumbnails.of("images/a380_1280x1024.jpg").size(1280,1024).outputFormat("png").toFile("c:/a380_1280x1024.png");

8、输出到OutputStream

//toOutputStream(流对象)

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"));

原文地址：https://www.cnblogs.com/grasp/p/9689669.html