java 生成缩略图 Java缩略图生成库之Thumbnailator应用说明

//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");

//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"));