java 缩略图处理

java中用Thumbnailator对图片各种处理的方法

jar自己网上下载一下，maven的话添加依赖即可
<!-- https://mvnrepository.com/artifact/net.coobird/thumbnailator -->
<dependency>
    <groupId>net.coobird</groupId>
    <artifactId>thumbnailator</artifactId>
    <version>0.4.8</version>
</dependency>

 

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,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,200).keepAspectRatio(false).toFile( "C:/image_region_bootom_right.jpg"); /** * 指定坐标 */ Thumbnails.of("images/test.jpg").sourceRegion(600,500,400).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")); }