使用Thumbnails工具對圖片進行縮放，壓縮

Thumbnails是Google公司開源的圖片處理工具

一、將Thumbnails引入到maven工程

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

二、關鍵代碼

String filePathName = "需要壓縮的圖片根路徑";
String thumbnailFilePathName = "壓縮之后的圖片路徑";
double scale = 1d;//圖片縮小倍數(0~1),1代表保持原有的大小
double quality = 1d;//壓縮的質量,1代表保持原有的大小(默認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);//變為400*500,遵循原圖比例縮或放到400*某個高度

三、Spring-boot的例子

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:保存圖片並且生成縮略圖
     * @param imageFile 圖片文件
     * @param request 請求對象
     * @param uploadPath 上傳目錄
     * @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;//壓縮之后的圖片最大寬度
        if (imageFile == null) {
            result.put("msg", "imageFile不能為空");
            return result.toJSONString();
        }

        if (imageFile.getSize() >= 10 * 1024 * 1024) {
            result.put("msg", "文件不能大於10M");
            return result.toJSONString();
        }
        String uuid = UUID.randomUUID().toString();

        String fileDirectory = new SimpleDateFormat("yyyyMMdd").format(new Date());//設置日期格式

        //拼接后台文件名稱
        String pathName = fileDirectory + File.separator + uuid + "."
                + FilenameUtils.getExtension(imageFile.getOriginalFilename());
        //構建保存文件路徑
        //修改上傳路徑為服務器上
        String realPath = "F:/桌面temp/ys";//request.getServletContext().getRealPath("uploadPath");
        //獲取服務器絕對路徑 linux 服務器地址  獲取當前使用的配置文件配置
        //String urlString=PropertiesUtil.getInstance().getSysPro("uploadPath");
        //拼接文件路徑
        String filePathName = realPath + File.separator + pathName;
        log.info("圖片上傳路徑：" + filePathName);
        //判斷文件保存是否存在
        File file = new File(filePathName);
        if (file.getParentFile() != null || !file.getParentFile().isDirectory()) {
            //創建文件
            file.getParentFile().mkdirs();
        }

        InputStream inputStream = null;
        FileOutputStream fileOutputStream = null;
        try {
            inputStream = imageFile.getInputStream();
            fileOutputStream = new FileOutputStream(file);
            //寫出文件
//            IOUtils.copy(inputStream, fileOutputStream);
            byte[] buffer = new byte[2048];
            IOUtils.copyLarge(inputStream, fileOutputStream, buffer);
            buffer = null;

        } catch (IOException e) {
            filePathName = null;
            result.put("msg", "操作失敗");
            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", "操作失敗");
                return result.toJSONString();

            }
        }

        //拼接后台文件名稱
        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) {//當圖片超過200kb的時候進行壓縮處理
            if (size > 0) {
                quality = (200 * 1024f) / size;
            }
        }

        //圖片信息
        double width = 0;
        double height = 0;
        try {
            BufferedImage bufferedImage = ImageIO.read(imageFile.getInputStream()); //獲取圖片流
            if (bufferedImage == null) {
                // 證明上傳的文件不是圖片，獲取圖片流失敗，不進行下面的操作
            }
            width = bufferedImage.getWidth(); // 通過圖片流獲取圖片寬度
            height = bufferedImage.getHeight(); // 通過圖片流獲取圖片高度
            // 省略邏輯判斷
        } catch (Exception e) {
            // 省略異常操作
        }
        System.out.println(width);
        while (width * scale > maxWidth) {//處理圖片像素寬度（當像素大於1200時進行圖片等比縮放寬度）
            scale -= 0.1;
        }

        //拼接文件路徑
        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 {
            //注釋掉之前長寬的方式，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", "操作失敗");
            return result.toJSONString();
        }
        /**
         * 縮略圖end
         */

        //原圖地址
        result.put("originalUrl", pathName);
        //縮略圖地址
        result.put("thumbnailUrl", thumbnailPathName);
        //縮略圖地址
        result.put("msg", "操作成功");
        result.put("status", 200);
        return result.toJSONString();
    }
}