檔案上傳是一個最基本的功能，往往我們需要對圖片進行壓縮，來加快移動端的載入速度。

SprimgMVC圖片上傳可以參考SpringMVC傳值

從這裡開始

System.out.println("檔案大小: " + file.getSize());
            System.out.println("檔案型別: " + file.getContentType());
            System.out.println("表單名稱: " + file.getName());
            System.out.println("檔案原名: " + file.getOriginalFilename
 
());
            if (!file.getContentType().contains("image")) {
                return BaseReturn.response(ErrorCode.FAILURE, "不支援的圖片型別：" + file.getContentType());
            }
            String image = ImageService.saveImage(request, file, uploadPath);

相關依賴

    <!-- 圖片壓縮 -->
    <dependency>
        <groupId>net.coobird</groupId>
        <artifactId>thumbnailator</artifactId>
        <version>0.4.8</version>
    </dependency>
    <!-- cmyk格式圖片轉換 -->
    <dependency>
        <groupId>com.twelvemonkeys.imageio</groupId>
        <artifactId>imageio-jpeg</artifactId>
        <version>3.3</version>
    </dependency>
    <dependency>
        <groupId>com.twelvemonkeys.imageio</groupId>
        <artifactId>imageio-tiff</artifactId>
        <version>3.3</version>
    </dependency>
 

ImageService

package com.jrbac.service;

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.imageio.stream.ImageOutputStream;
import javax.servlet.http.HttpServletRequest;

import org.apache.commons.io.FileUtils;
import org.slf
 
4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.multipart.MultipartFile;

import com.jrbac.util.UUIDGenerator;

import net.coobird.thumbnailator.Thumbnails;

public class ImageService {
    private static final Logger logger = LoggerFactory.getLogger(ImageService.class);

    /**
     * @param request
     * @param file
     * @param uploadPath
     *            形如這樣的/assets/upload/image/
     * @return /assets/upload/image/abc.jpg
     * @throws IOException
     */
    public static String saveImage(HttpServletRequest request, MultipartFile file, String uploadPath) {
        // 如果用的是Tomcat伺服器，則檔案會上傳到\\%TOMCAT_HOME%\\webapps\\YourWebProject\\uploadPath\\資料夾中
        // String fileName = file.getOriginalFilename();
        // String fileExt[] = fileName.split("\\.");
        String ext = file.getContentType().split("\\/")[1];
        String newFileName = UUIDGenerator.getUUID() + "." + ext;
        String realPath = request.getSession().getServletContext().getRealPath(uploadPath);
        String filePathAndName = null;
        if (realPath.endsWith(File.separator)) {
            filePathAndName = realPath + newFileName;
        } else {
            filePathAndName = realPath + File.separator + newFileName;
        }
        logger.info("-----上傳的檔案:{}-----", filePathAndName);
        try {
            // 先把檔案儲存到本地
            FileUtils.copyInputStreamToFile(file.getInputStream(), new File(realPath, newFileName));
        } catch (IOException e1) {
            logger.error("-----檔案儲存到本地發生異常:{}-----", e1.getMessage());
        }
        int big = 2 * 1024 * 1024; // 2M以上就進行0.6壓縮
        if (file.getSize() > big) {
            thumbnail(filePathAndName, 0.6f);
        } else {
            thumbnail(filePathAndName, 0.8f);
        }
        return uploadPath + newFileName;
    }

    private static void thumbnail(String filePathAndName, double size) {
        try {
            Thumbnails.of(filePathAndName).scale(size).toFile(filePathAndName);
        } catch (IOException e) {
            logger.error("-----讀取圖片發生異常:{}-----", e.getMessage());
            logger.info("-----嘗試cmyk轉化-----");
            File cmykJPEGFile = new File(filePathAndName);
            try {
                BufferedImage image = ImageIO.read(cmykJPEGFile);
                ImageOutputStream output = ImageIO.createImageOutputStream(cmykJPEGFile);
                if (!ImageIO.write(image, "jpg", output)) {
                    logger.info("-----cmyk轉化異常:{}-----");
                }
                Thumbnails.of(image).scale(0.4f).toFile(filePathAndName);
                logger.info("-----cmyk轉化成功-----");
            } catch (IOException e1) {
                logger.info("-----cmyk轉化異常:{}-----", e1.getMessage());
            }
        }
    }
}

這裡有一點需要解釋一下

FileUtils.copyInputStreamToFile(file.getInputStream(), new File(realPath, newFileName));

會將圖片儲存到本地，

這一步沒問題

問題會發生在

Thumbnails.of(filePathAndName).scale(size).toFile(filePathAndName);

大部分情況下是不會出問題的，如果

P過的圖片儲存為jpg格式時，預設的模式是CMYK模式

就會報如下錯誤

javax.imageio.IIOException: Unsupported Image Type

參考文獻