// 獲得SpringBoot提供的mongodb的GridFS物件
@Autowired
private GridFsTemplate gridFsTemplate;

public ServiceResult<FileInfoAO> compressUploadFile(HttpServletRequest request) {
    try {
        Part part = request.getPart("file");
        // 獲得提交的檔名
        String fileName = part.getSubmittedFileName();
        // 獲得檔案型別
        String contentType = part.getContentType();
        // 獲得檔案輸入流
        InputStream ins = part.getInputStream();
        BufferedImage image = Thumbnails.of(ins).scale(1f).outputQuality(0.25f).asBufferedImage();
        ByteArrayOutputStream os = new ByteArrayOutputStream();
        ImageIO.write(image, "jpg", os);
        InputStream is = new ByteArrayInputStream(os.toByteArray());
        // 將檔案儲存到mongodb中,mongodb 將會返回這個檔案的具體資訊
        GridFSFile gridFSFile = gridFsTemplate.store(is, fileName, contentType);
        FileInfoAO fileInfo = new FileInfoAO();
        fileInfo.setContentType(contentType);
        fileInfo.setFileName(fileName);
        fileInfo.setMongoFileId(gridFSFile.getId().toString());
        return ServiceResultHelper.genResultWithSuccess(fileInfo);
    } catch (Exception e) {
        return ServiceResultHelper.genResultWithFaild("圖片上傳失敗", -1);
    }
}
 

Thumbnails 依賴包

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

返回結果取mongoFileId 然後下載

{
    "succeed": true,
    "code": 200,
    "subCode": 200,
    "msg": "成功",
    "data": {
        "contentType": "image/jpeg",
        "fileName": "2.jpg",
        "mongoFileId": "5bdfb9807f76271da8bac485",
        "lastUpdateBy": "25540194153267202"
    },
    "additionalProperties": {}
}

/**
 * 下載檔案
 *
 * @param fileId   檔案id
 * @param request
 * @param response
 */
@Override
public void downloadFile(String fileId, HttpServletRequest request, HttpServletResponse response) {
    Query query = Query.query(Criteria.where("_id").is(fileId));
    // 查詢單個檔案
    GridFSDBFile gfsfile = gridFsTemplate.findOne(query);
    try {
        if (gfsfile == null) {
            return;
        }
        String fileName = gfsfile.getFilename().replace(",", "");
        //處理中文檔名亂碼
        if (request.getHeader("User-Agent").toUpperCase().contains("MSIE") ||
                request.getHeader("User-Agent").toUpperCase().contains("TRIDENT")
                || request.getHeader("User-Agent").toUpperCase().contains("EDGE")) {
            fileName = java.net.URLEncoder.encode(fileName, "UTF-8");
        } else {
            //非IE瀏覽器的處理：
            fileName = new String(fileName.getBytes("UTF-8"), "ISO-8859-1");
        }
        // 通知瀏覽器進行檔案下載
        response.setContentType(gfsfile.getContentType());
        response.setHeader("Content-Disposition", "attachment;filename=\"" + fileName + "\"");
        gfsfile.writeTo(response.getOutputStream());
    } catch (IOException e) {

    }
}