//size(宽度, 高度)  

    /*

     * 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/a380_1280x1024.jpg")

            .size(200, 300)

            .toFile("c:/a380_200x300.jpg");  

    Thumbnails.of("images/a380_1280x1024.jpg")

            .size(2560, 2048)

            .toFile("c:/a380_2560x2048.jpg");  

Java代码  收藏代码

    //scale(比例)

    Thumbnails.of("images/a380_1280x1024.jpg")

            .scale(0.25f)

            .toFile("c:/a380_25%.jpg");  

    Thumbnails.of("images/a380_1280x1024.jpg")

            .scale(1.10f)

            .toFile("c:/a380_110%.jpg"); 

//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")

//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");   

Thumbnails.of("images/a380_1280x1024.jpg")

        .size(1280, 1024)

        .rotate(-90)

        .toFile("c:/a380_rotate-90.jpg");

    //watermark(位置，水印图，透明度)

    Thumbnails.of("images/a380_1280x1024.jpg")

            .size(1280, 1024)

            .watermark(Positions.BOTTOM_RIGHT, ImageIO.read(new File("images/watermark.png")), 0.5f)

            .outputQuality(0.8f)

            .toFile("c:/a380_watermark_bottom_right.jpg");  

    Thumbnails.of("images/a380_1280x1024.jpg")

            .size(1280, 1024)

            .watermark(Positions.CENTER, ImageIO.read(new File("images/watermark.png")), 0.5f)

            .outputQuality(0.8f)

            .toFile("c:/a380_watermark_center.jpg");  

    //sourceRegion()  

    //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");  

    //图片右下400*400的区域

    Thumbnails.of("images/a380_1280x1024.jpg")

            .sourceRegion(Positions.BOTTOM_RIGHT, 400,400)

            .size(200, 200)

            .keepAspectRatio(false)

            .toFile("c:/a380_region_bootom_right.jpg");  

    //指定坐标

    Thumbnails.of("images/a380_1280x1024.jpg")

            .sourceRegion(600, 500, 400, 400)

            .size(200, 200)

            .keepAspectRatio(false)

            .toFile("c:/a380_region_coord.jpg");  

//outputFormat(图像格式)

Thumbnails.of("images/a380_1280x1024.jpg")

        .size(1280, 1024)

        .outputFormat("png")

        .toFile("c:/a380_1280x1024.png");   

Thumbnails.of("images/a380_1280x1024.jpg")

        .size(1280, 1024)

        .outputFormat("gif")

        .toFile("c:/a380_1280x1024.gif"); 

    //toOutputStream(流对象)

    OutputStream os = new FileOutputStream("c:/a380_1280x1024_OutputStream.png");

    Thumbnails.of("images/a380_1280x1024.jpg")

            .size(1280, 1024)

            .toOutputStream(os);  

//asBufferedImage() 返回BufferedImage

BufferedImage thumbnail = Thumbnails.of("images/a380_1280x1024.jpg")

        .size(1280, 1024)

        .asBufferedImage();

ImageIO.write(thumbnail, "jpg", new File("c:/a380_1280x1024_BufferedImage.jpg"));