Thumbnailator 是一个用来生成图像缩略图、裁切、旋转、添加水印等操作的 Java 类库，通过很简单的代码即可生成图片缩略图，也可直接对一整个目录的图片生成缩略图。

Thumbnailator对图片的简单操作代码如下：

import java.awt.image.BufferedImage;  import java.io.File;  import java.io.FileOutputStream;  import java.io.IOException;  import java.io.OutputStream;    import javax.imageio.ImageIO;    import net.coobird.thumbnailator.Thumbnails;  import net.coobird.thumbnailator.geometry.Positions;    /**   *    * @author yaohucaizi   *    */  public class ThumbnailatorTest {     /**    *     * @param args    * @throws IOException    */   public static void main(String[] args) throws IOException {    ThumbnailatorTest thumbnailatorTest = new ThumbnailatorTest();    thumbnailatorTest.test1();    thumbnailatorTest.test2();    thumbnailatorTest.test3();    thumbnailatorTest.test4();    thumbnailatorTest.test5();    thumbnailatorTest.test6();    thumbnailatorTest.test7();    thumbnailatorTest.test8();    thumbnailatorTest.test9();   }     /**    * 指定大小进行缩放    *     * @throws IOException    */   private void test1() throws IOException {    /*     * size(width,height) 若图片横比200小，高比300小，不变     * 若图片横比200小，高比300大，高缩小到300，图片比例不变 若图片横比200大，高比300小，横缩小到200，图片比例不变     * 若图片横比200大，高比300大，图片按比例缩小，横为200或高为300     */    Thumbnails.of("images/test.jpg").size(200, 300).toFile(      "C:/image_200x300.jpg");    Thumbnails.of("images/test.jpg").size(2560, 2048).toFile(      "C:/image_2560x2048.jpg");   }     /**    * 按照比例进行缩放    *     * @throws IOException    */   private void test2() throws IOException {    /**     * scale(比例)     */    Thumbnails.of("images/test.jpg").scale(0.25f)      .toFile("C:/image_25%.jpg");    Thumbnails.of("images/test.jpg").scale(1.10f).toFile(      "C:/image_110%.jpg");   }     /**    * 不按照比例，指定大小进行缩放    *     * @throws IOException    */   private void test3() throws IOException {    /**     * keepAspectRatio(false) 默认是按照比例缩放的     */    Thumbnails.of("images/test.jpg").size(120, 120).keepAspectRatio(false)      .toFile("C:/image_120x120.jpg");   }     /**    * 旋转    *     * @throws IOException    */   private void test4() throws IOException {    /**     * rotate(角度),正数：顺时针 负数：逆时针     */    Thumbnails.of("images/test.jpg").size(1280, 1024).rotate(90).toFile(      "C:/image+90.jpg");    Thumbnails.of("images/test.jpg").size(1280, 1024).rotate(-90).toFile(      "C:/iamge-90.jpg");   }     /**    * 水印    *     * @throws IOException    */   private void test5() throws IOException {    /**     * watermark(位置，水印图，透明度)     */    Thumbnails.of("images/test.jpg").size(1280, 1024).watermark(      Positions.BOTTOM_RIGHT,      ImageIO.read(new File("images/watermark.png")), 0.5f)      .outputQuality(0.8f).toFile(        "C:/image_watermark_bottom_right.jpg");    Thumbnails.of("images/test.jpg").size(1280, 1024).watermark(      Positions.CENTER,      ImageIO.read(new File("images/watermark.png")), 0.5f)      .outputQuality(0.8f).toFile("C:/image_watermark_center.jpg");   }     /**    * 裁剪    *     * @throws IOException    */   private void test6() throws IOException {    /**     * 图片中心400*400的区域     */    Thumbnails.of("images/test.jpg").sourceRegion(Positions.CENTER, 400,      400).size(200, 200).keepAspectRatio(false).toFile(      "C:/image_region_center.jpg");    /**     * 图片右下400*400的区域     */    Thumbnails.of("images/test.jpg").sourceRegion(Positions.BOTTOM_RIGHT,      400, 400).size(200, 200).keepAspectRatio(false).toFile(      "C:/image_region_bootom_right.jpg");    /**     * 指定坐标     */    Thumbnails.of("images/test.jpg").sourceRegion(600, 500, 400, 400).size(      200, 200).keepAspectRatio(false).toFile(      "C:/image_region_coord.jpg");   }     /**    * 转化图像格式    *     * @throws IOException    */   private void test7() throws IOException {    /**     * outputFormat(图像格式)     */    Thumbnails.of("images/test.jpg").size(1280, 1024).outputFormat("png")      .toFile("C:/image_1280x1024.png");    Thumbnails.of("images/test.jpg").size(1280, 1024).outputFormat("gif")      .toFile("C:/image_1280x1024.gif");   }     /**    * 输出到OutputStream    *     * @throws IOException    */   private void test8() throws IOException {    /**     * toOutputStream(流对象)     */    OutputStream os = new FileOutputStream(      "C:/image_1280x1024_OutputStream.png");    Thumbnails.of("images/test.jpg").size(1280, 1024).toOutputStream(os);   }     /**    * 输出到BufferedImage    *     * @throws IOException    */   private void test9() throws IOException {    /**     * asBufferedImage() 返回BufferedImage     */    BufferedImage thumbnail = Thumbnails.of("images/test.jpg").size(1280,      1024).asBufferedImage();    ImageIO.write(thumbnail, "jpg", new File(      "C:/image_1280x1024_BufferedImage.jpg"));   }  }