Java縮略圖生成庫--Thumbnailator

1、指定大小進行縮放

//size(寬度, 高度) 

/* 
* 若圖片橫比200小，高比300小，不變 
* 若圖片橫比200小，高比300大，高縮小到300，圖片比例不變 
* 若圖片橫比200大，高比300小，橫縮小到200，圖片比例不變 
* 若圖片橫比200大，高比300大，圖片按比例縮小，橫爲200或高爲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、按照比例進行縮放

//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，指定大小進行縮放

//keepAspectRatio(false) 默認是按照比例縮放的 
Thumbnails.of("images/a380_1280x1024.jpg") 
.size(200, 200) 
.keepAspectRatio(false) 
.toFile("c:/a380_200x200.jpg");

4、旋轉

//rotate(角度),正數：順時針 負數：逆時針 
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"); 

5、水印

//watermark(位置，水印圖，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");

6、裁剪

//sourceRegion() 

//圖片中心400*400的區域 
Thumbnails.of("images/a380_1280x1024.jpg") 
.sourceRegion(Positions.CENTER, 400,400) 
.size(200, 200) 
.keepAspectRatio(false) 
.toFile("c:/a380_region_center.jpg"); 

//圖片右下400*400的區域 
Thumbnails.of("images/a380_1280x1024.jpg") 
.sourceRegion(Positions.BOTTOM_RIGHT, 400,400) 
.size(200, 200) 
.keepAspectRatio(false) 
.toFile("c:/a380_region_bootom_right.jpg"); 

//指定座標 
Thumbnails.of("images/a380_1280x1024.jpg") 
.sourceRegion(600, 500, 400, 400) 
.size(200, 200) 
.keepAspectRatio(false) 
.toFile("c:/a380_region_coord.jpg");

7、轉化圖像格式

//outputFormat(圖像格式) 
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、輸出到OutputStream

//toOutputStream(流對象) 
OutputStream os = new FileOutputStream("c:/a380_1280x1024_OutputStream.png"); 
Thumbnails.of("images/a380_1280x1024.jpg") 
.size(1280, 1024) 
.toOutputStream(os);

9、輸出到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")); 

以下代碼親測：

public static void main(String[] args) throws IOException {
  private static String basePath = Thread.currentThread().getContextClassLoader().getResource("").getPath();//classpath路徑
		Thumbnails.of(new File("C:/Users/THINK/Desktop/ceshi2.png"))
		.size(200, 200).watermark(Positions.BOTTOM_RIGHT, 
		     ImageIO.read(new File(basePath+"/12311.png")), 0.25f)  // 12311.png是要添加的水印圖片
                     .outputQuality(0.8f).toFile("C:/Users/THINK/Desktop/ceshi23.png");
		System.out.println("執行完成===");
	}