Java生成缩略图之Thumbnailator

Thumbnailator 是一个为Java界面更流畅的缩略图生成库。从API提供现有的图像文件和图像对象的缩略图中简化了缩略过程，两三行代码就能够从现有图片生成缩略图，且允许微调缩略图生成，同时保持了需要写入到最低限度的代码量。同时还支持根据一个目录批量生成缩略图。

​​​http://code.google.com/p/thumbnailator/ ​​​
版本：thumbnailator-0.4.2.jar

原图如下：
[img]http://dl.iteye.com/upload/attachment/0069/0736/c595d657-a519-3c37-9ed5-26325dcc950b.jpg[/img]
1、指定大小进行缩放

//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");

2、按照比例进行缩放

//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");

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");   

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

[img]http://dl.iteye.com/upload/attachment/0069/0738/4784b936-eb09-343f-be28-ca6640cfc2e6.jpg[/img]

[img]http://dl.iteye.com/upload/attachment/0069/0740/e9e7a241-1fd9-31e9-8a44-c64aa7241740.jpg[/img]

5、水印

//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");

[img]http://dl.iteye.com/upload/attachment/0069/0742/9d96ecbb-bfac-3b06-a684-bc3e5ff98e06.jpg[/img]

[img]http://dl.iteye.com/upload/attachment/0069/0744/860545cc-4f24-3224-a94f-67757ee3d944.jpg[/img]

6、裁剪

//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");

[img]http://dl.iteye.com/upload/attachment/0069/0747/195a571b-5084-35b9-9d0b-199cea21ff3e.jpg[/img]

[img]http://dl.iteye.com/upload/attachment/0069/0749/e93b8bd0-e2ea-3a2d-af00-c465205eead8.jpg[/img]

[img]http://dl.iteye.com/upload/attachment/0069/0751/8866487f-c5a4-3fbd-97b3-eceefcd53f14.jpg[/img]

7、转化图像格式

//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");

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