<dependency><groupId>net.coobird</groupId><artifactId>thumbnailator</artifactId><version>0.4.8</version>
</dependency>

String filePathName = "需要压缩的图片根路径";
String thumbnailFilePathName = "压缩之后的图片路径";
double scale = 1d;//图片缩小倍数(0~1),1代表保持原有的大小
double quality = 1d;//压缩的质量,1代表保持原有的大小(默认1)

Thumbnails.of(filePathName).scale(scale).outputQuality(quality).outputFormat("jpg").toFile(thumbnailFilePathName);Thumbnails.of(filePathName).scale(scale).outputFormat("jpg").toFile(thumbnailFilePathName);Thumbnails.of(filePathName).size(400,500).toFile(thumbnailFilePathName);//变为400*500,遵循原图比例缩或放到400*某个高度

package com.example.atlogging.controller;import com.alibaba.fastjson.JSONObject;
import net.coobird.thumbnailator.Thumbnails;
import org.apache.commons.io.FilenameUtils;
import org.apache.commons.io.IOUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.multipart.MultipartFile;import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.UUID;@RestController
@RequestMapping(path = "/thumb", produces = "application/json;charset=UTF-8")
public class TestThumbnails {/*** @Description:保存图片并且生成缩略图* @param imageFile 图片文件* @param request 请求对象* @param uploadPath 上传目录* @return*/private static Logger log = LoggerFactory.getLogger(TestThumbnails.class);@RequestMapping("/up")public String testThumb(MultipartFile imageFile, HttpServletRequest request) {String res = this.uploadFileAndCreateThumbnail(imageFile, request, "");return res;}public static String uploadFileAndCreateThumbnail(MultipartFile imageFile, HttpServletRequest request, String uploadPath) {JSONObject result = new JSONObject();int maxWidth = 1200;//压缩之后的图片最大宽度if (imageFile == null) {result.put("msg", "imageFile不能为空");return result.toJSONString();}if (imageFile.getSize() >= 10 * 1024 * 1024) {result.put("msg", "文件不能大于10M");return result.toJSONString();}String uuid = UUID.randomUUID().toString();String fileDirectory = new SimpleDateFormat("yyyyMMdd").format(new Date());//设置日期格式//拼接后台文件名称String pathName = fileDirectory + File.separator + uuid + "."+ FilenameUtils.getExtension(imageFile.getOriginalFilename());//构建保存文件路径//修改上传路径为服务器上String realPath = "F:/桌面temp/ys";//request.getServletContext().getRealPath("uploadPath");//获取服务器绝对路径 linux 服务器地址  获取当前使用的配置文件配置//String urlString=PropertiesUtil.getInstance().getSysPro("uploadPath");//拼接文件路径String filePathName = realPath + File.separator + pathName;log.info("图片上传路径：" + filePathName);//判断文件保存是否存在File file = new File(filePathName);if (file.getParentFile() != null || !file.getParentFile().isDirectory()) {//创建文件
            file.getParentFile().mkdirs();}InputStream inputStream = null;FileOutputStream fileOutputStream = null;try {inputStream = imageFile.getInputStream();fileOutputStream = new FileOutputStream(file);//写出文件
//            IOUtils.copy(inputStream, fileOutputStream);byte[] buffer = new byte[2048];IOUtils.copyLarge(inputStream, fileOutputStream, buffer);buffer = null;} catch (IOException e) {filePathName = null;result.put("msg", "操作失败");return result.toJSONString();} finally {try {if (inputStream != null) {inputStream.close();}if (fileOutputStream != null) {fileOutputStream.flush();fileOutputStream.close();}} catch (IOException e) {filePathName = null;result.put("msg", "操作失败");return result.toJSONString();}}//拼接后台文件名称String thumbnailPathName = fileDirectory + File.separator + uuid + "small."+ FilenameUtils.getExtension(imageFile.getOriginalFilename());if (thumbnailPathName.contains(".png")) {thumbnailPathName = thumbnailPathName.replace(".png", ".jpg");}long size = imageFile.getSize();double scale = 1d;double quality = 1d;if (size >= 200 * 1024) {//当图片超过200kb的时候进行压缩处理if (size > 0) {quality = (200 * 1024f) / size;}}//图片信息double width = 0;double height = 0;try {BufferedImage bufferedImage = ImageIO.read(imageFile.getInputStream()); //获取图片流if (bufferedImage == null) {// 证明上传的文件不是图片，获取图片流失败，不进行下面的操作
            }width = bufferedImage.getWidth(); // 通过图片流获取图片宽度height = bufferedImage.getHeight(); // 通过图片流获取图片高度// 省略逻辑判断} catch (Exception e) {// 省略异常操作
        }System.out.println(width);while (width * scale > maxWidth) {//处理图片像素宽度（当像素大于1200时进行图片等比缩放宽度）scale -= 0.1;}//拼接文件路径String thumbnailFilePathName = realPath + File.separator + thumbnailPathName;System.out.println(scale);System.out.println(quality);System.out.println((int) width * scale);/*if(true){return result.toJSONString();}*/try {//注释掉之前长宽的方式，改用大小
//          Thumbnails.of(filePathName).size(width, height).toFile(thumbnailFilePathName);if (size < 200 * 1024) {Thumbnails.of(filePathName).scale(scale).outputFormat("jpg").toFile(thumbnailFilePathName);} else {Thumbnails.of(filePathName).scale(scale).outputQuality(quality).outputFormat("jpg").toFile(thumbnailFilePathName);//(thumbnailFilePathName + "l.");
            }} catch (Exception e1) {result.put("msg", "操作失败");return result.toJSONString();}/*** 缩略图end*///原图地址result.put("originalUrl", pathName);//缩略图地址result.put("thumbnailUrl", thumbnailPathName);//缩略图地址result.put("msg", "操作成功");result.put("status", 200);return result.toJSONString();}
}