一.Thumbnails用法介绍：
1.按指定大小把图片进行缩和放（会遵循原图高宽比例）
//此处把图片压成400×500的缩略图
//变为400*300,遵循原图比例缩或放到400*某个高度
Thumbnails.of(fromPic).size(400,500).toFile(toPic);
//按照比例进行缩小和放大
Thumbnails.of(fromPic).scale(0.2f).toFile(toPic);//按比例缩小
Thumbnails.of(fromPic).scale(2f);//按比例放大
//不按比例，就按指定的大小进行缩放
Thumbnails.of(fromPic).size(100, 100).keepAspectRatio(false).toFile(toPic);
//或者
Thumbnails.of(fromPic).forceSize(100,100).toFile(toPic);
2.旋转图片
rotate(角度),正数则为顺时针，负数则为逆时针
Thumbnails.of(fromPic).size(200,200).rotate(90).toFile(toPic);
3.图片尺寸不变，压缩图片文件大小outputQuality实现,参数1为最高质量
Thumbnails.of(fromPic).scale(1f).outputQuality(0.25f).toFile(toPic);
4.给图片加水印，watermark(位置，水印图，透明度)Positions.CENTER表示加在中间
Thumbnails.of(fromPic).size(400,400)
.watermark(Positions.CENTER,ImageIO.read(waterPic),0.5f)
.outputQuality(0.8f).toFile(toPic);
5.用sourceRegion()实现图片裁剪
//图片中心300*300的区域,Positions.CENTER表示中心，还有许多其他位置可选
Thumbnails.of(fromPic).sourceRegion(Positions.CENTER,300,300)
.size(300,300).toFile(toPic);
//图片中上区域300*300的区域
Thumbnails.of(fromPic).sourceRegion(Positions.TOP_CENTER,300,300)
.size(300,300).toFile(toPic);
Thumbnails.of(fromPic).sourceRegion(0,0,200,200)
.size(300,300).toFile(toPic);
以上资料摘自：https://www.cnblogs.com/ryan304/p/9546670.html
二开始实操：将图片文件使用Thumbnails图片压缩处理后转换为base64字符串
1.添加maven依赖：
<dependency>
<groupId>net.coobird</groupId>
<artifactId>thumbnailator</artifactId>
<version>0.4.8</version>
</dependency>
编写工具类
/**
* @author 猿份哥
* @description
* @createTime 2019/8/04 18:37
*/
public class ImageUtils {
private static String ImageFormat="jpg";
/**
* 按照比例和规格压缩图片得到base64图片字符串
* @param maxSize 单位kb
* @param w
* @param h
* @return
*/
public static String resizeImage(String filePath,int maxSize,int w,int h){
try {
BufferedImage src = fileToBufferedImage(filePath);
BufferedImage output = Thumbnails.of(src).size(w, h).asBufferedImage();
String base64 = imageToBase64(output);
while (base64.length() - base64.length() / 8 * 2 > maxSize*1000) {
output = Thumbnails.of(output).scale(0.9f).asBufferedImage();
base64 = imageToBase64(output);
}
return imageToBase64(output);
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
/**
* 图片文件转BufferedImage
* @param filePath
* @return
* @throws Exception
*/
public static BufferedImage fileToBufferedImage(String filePath) throws Exception{
FileInputStream is=new FileInputStream(filePath);
BufferedImage img = ImageIO.read(is);
return img;
}
/**
* 将图片base64字符串转换为BufferedImage
* @param base64string
* @return
*/
public static BufferedImage base64String2BufferedImage(String base64string) {
BufferedImage image = null;
try {
InputStream stream = base64StringToInputStream(base64string);
image = ImageIO.read(stream);
} catch (IOException e) {
e.printStackTrace();
}
return image;
}
/**
* 将base64字符转换为输入流
* @param base64string
* @return
*/
private static InputStream base64StringToInputStream(String base64string) {
ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(base64string.getBytes());
InputStream inputStream=byteArrayInputStream;
return inputStream;
}
/**
* 将BufferedImage转换为base64字符串
* @param bufferedImage
* @return
*/
public static String imageToBase64(BufferedImage bufferedImage) {
Base64 encoder = new Base64();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
try {
ImageIO.write(bufferedImage, ImageFormat, baos);
} catch (IOException e) {
e.printStackTrace();
}
return new String(encoder.encode((baos.toByteArray())));
}
}
resizeImage方法使用while循环将图片大小于压缩到指定的大小后不再压缩。
编写测试类
/**
* @author 猿份哥
* @description
* @createTime 2019/8/04 16:35
*/
@SpringBootTest
@RunWith(SpringRunner.class)
public class ImageTest {
@Test
public void imageFileToBase64() throws Exception {
String filePath="D:\\data\\test\\0.jpg";
String imageStr = ImageUtils.resizeImage(filePath, 60, 300, 420);
System.out.println(imageStr);
}
}
最后猿份哥双手给大家奉上代码地址，希望大家喜欢
https://github.com/tiankonglanlande/springboot/tree/master/springboot-thumbnailator-base64
注意：本文归作者所有，未经作者允许，不得转载
