若依 springBoot2.5 +vue2前后端分离，实现图片上传及下载功能。

1. 图片上传

1. vue 前端，引入< image-upload />组件。

<el-row>
   <el-col :span="12">
     <el-form-item label="头像" prop="avatar">
       <image-upload v-model="form.avatar" :limit="1"/>
     </el-form-item>
   </el-col>
 </el-row>

< image-upload />组件 源码：

<template>
  <div class="component-upload-image">
    <el-upload
      :action="uploadImgUrl"
      list-type="picture-card"
      :on-success="handleUploadSuccess"
      :before-upload="handleBeforeUpload"
      :limit="limit"
      :on-error="handleUploadError"
      :on-exceed="handleExceed"
      ref="imageUpload"
      :on-remove="handleDelete"
      :show-file-list="true"
      :headers="headers"
      :file-list="fileList"
      :on-preview="handlePictureCardPreview"
      :class="{hide: this.fileList.length >= this.limit}"
    >
      <i class="el-icon-plus"></i>
    </el-upload>

    <!-- 上传提示 -->
    <div class="el-upload__tip" slot="tip" v-if="showTip">
      请上传
      <template v-if="fileSize"> 大小不超过 <b style="color: #f56c6c">{{ fileSize }}MB</b> </template>
      <template v-if="fileType"> 格式为 <b style="color: #f56c6c">{{ fileType.join("/") }}</b> </template>
      像素为 <b style="color: #f56c6c">320 x 320 </b>
      的文件
    </div>

    <el-dialog
      :visible.sync="dialogVisible"
      title="预览"
      width="800"
      append-to-body
    >
      <img
        :src="dialogImageUrl"
        style="display: block; max-width: 100%; margin: 0 auto"
      />
    </el-dialog>
  </div>
</template>

<script>
import { getToken } from "@/utils/auth";
import {globalConfig} from "../../../public/config";
export default {
  props: {
    value: [String, Object, Array],
    // 图片数量限制
    limit: {
      type: Number,
      default: 5,
    },
    // 大小限制(MB)
    fileSize: {
       type: Number,
      default: 5,
    },
    // 文件类型, 例如['png', 'jpg', 'jpeg']
    fileType: {
      type: Array,
      default: () => ["png", "jpg", "jpeg"],
    },
    // 是否显示提示
    isShowTip: {
      type: Boolean,
      default: true
    }
  },
  data() {
    return {
      number: 0,
      uploadList: [],
      dialogImageUrl: "",
      dialogVisible: false,
      hideUpload: false,
      baseUrl: process.env.NODE_ENV === "production" ? globalConfig.reqUrl:process.env.VUE_APP_BASE_API,
      uploadImgUrl: (process.env.NODE_ENV === "production" ? globalConfig.reqUrl:process.env.VUE_APP_BASE_API) + "/common/upload", // 上传的图片服务器地址
      headers: {
        Authorization: "Bearer " + getToken(),
      },
      fileList: []
    };
  },
  watch: {
    value: {
      handler(val) {
        if (val) {
          // 首先将值转为数组
          const list = Array.isArray(val) ? val : this.value.split(',');
          // 然后将数组转为对象数组
          this.fileList = list.map(item => {
            if (typeof item === "string") {
              if (item.indexOf(this.baseUrl) === -1) {
                  item = { name: this.baseUrl + item, url: this.baseUrl + item };
              } else {
                  item = { name: item, url: item };
              }
            }
            return item;
          });
        } else {
          this.fileList = [];
          return [];
        }
      },
      deep: true,
      immediate: true
    }
  },
  computed: {
    // 是否显示提示
    showTip() {
      return this.isShowTip && (this.fileType || this.fileSize);
    },
  },
  methods: {
    // 上传前loading加载
    handleBeforeUpload(file) {
      let isImg = false;
      if (this.fileType.length) {
        let fileExtension = "";
        if (file.name.lastIndexOf(".") > -1) {
          fileExtension = file.name.slice(file.name.lastIndexOf(".") + 1);
        }
        isImg = this.fileType.some(type => {
          if (file.type.indexOf(type) > -1) return true;
          if (fileExtension && fileExtension.indexOf(type) > -1) return true;
          return false;
        });
      } else {
        isImg = file.type.indexOf("image") > -1;
      }

      if (!isImg) {
        this.$modal.msgError(`文件格式不正确, 请上传${this.fileType.join("/")}图片格式文件!`);
        return false;
      }
      if (this.fileSize) {
        const isLt = file.size / 1024 / 1024 < this.fileSize;
        if (!isLt) {
          this.$modal.msgError(`上传头像图片大小不能超过 ${this.fileSize} MB!`);
          return false;
        }
      }
      this.$modal.loading("正在上传图片，请稍候...");
      this.number++;
    },
    // 文件个数超出
    handleExceed() {
      this.$modal.msgError(`上传文件数量不能超过 ${this.limit} 个!`);
    },
    // 上传成功回调
    handleUploadSuccess(res, file) {
      if (res.code === 200) {
        this.uploadList.push({ name: res.fileName, url: res.fileName });
        this.uploadedSuccessfully();
      } else {
        this.number--;
        this.$modal.closeLoading();
        this.$modal.msgError(res.msg);
        this.$refs.imageUpload.handleRemove(file);
        this.uploadedSuccessfully();
      }
    },
    // 删除图片
    handleDelete(file) {
      const findex = this.fileList.map(f => f.name).indexOf(file.name);
      if(findex > -1) {
        this.fileList.splice(findex, 1);
        this.$emit("input", this.listToString(this.fileList));
      }
    },
    // 上传失败
    handleUploadError() {
      this.$modal.msgError("上传图片失败，请重试");
      this.$modal.closeLoading();
    },
    // 上传结束处理
    uploadedSuccessfully() {
      if (this.number > 0 && this.uploadList.length === this.number) {
        this.fileList = this.fileList.concat(this.uploadList);
        this.uploadList = [];
        this.number = 0;
        this.$emit("input", this.listToString(this.fileList));
        this.$modal.closeLoading();
      }
    },
    // 预览
    handlePictureCardPreview(file) {
      this.dialogImageUrl = file.url;
      this.dialogVisible = true;
    },
    // 对象转成指定字符串分隔
    listToString(list, separator) {
      let strs = "";
      separator = separator || ",";
      for (let i in list) {
        if (list[i].url) {
          strs += list[i].url.replace(this.baseUrl, "") + separator;
        }
      }
      return strs != '' ? strs.substr(0, strs.length - 1) : '';
    }
  }
};
</script>
<style scoped lang="scss">
// .el-upload--picture-card 控制加号部分
::v-deep.hide .el-upload--picture-card {
    display: none;
}
// 去掉动画效果
::v-deep .el-list-enter-active,
::v-deep .el-list-leave-active {
    transition: all 0s;
}

::v-deep .el-list-enter, .el-list-leave-active {
    opacity: 0;
    transform: translateY(0);
}
</style>

2. 后台
   CommonController.java

 /**
     * 通用上传请求（单个）
     */
    @PostMapping("/upload")
    public AjaxResult uploadFile(MultipartFile file) throws Exception {
        try {
            // 上传文件路径
            String filePath = RuoYiConfig.getUploadPath();
            // 上传并返回新文件名称
            String fileName = FileUploadUtils.upload(filePath, file);
            String url = serverConfig.getUrl() + fileName;
            AjaxResult ajax = AjaxResult.success();
            ajax.put("url", url);
            ajax.put("fileName", fileName);
            ajax.put("newFileName", FileUtils.getName(fileName));
            ajax.put("originalFilename", file.getOriginalFilename());
            return ajax;
        } catch (Exception e) {
            return AjaxResult.error(e.getMessage());
        }
    }

FileUploadUtils.java

package com.dechnic.common.utils.file;

import com.dechnic.common.config.RuoYiConfig;
import com.dechnic.common.constant.Constants;
import com.dechnic.common.exception.file.FileNameLengthLimitExceededException;
import com.dechnic.common.exception.file.FileSizeLimitExceededException;
import com.dechnic.common.exception.file.InvalidExtensionException;
import com.dechnic.common.utils.DateUtils;
import com.dechnic.common.utils.StringUtils;
import com.dechnic.common.utils.uuid.Seq;
import org.apache.commons.io.FilenameUtils;
import org.springframework.web.multipart.MultipartFile;

import java.io.File;
import java.io.IOException;
import java.nio.file.Paths;
import java.util.Objects;

/**
 * 文件上传工具类
 *
 * @author ruoyi
 */
public class FileUploadUtils
{
    /**
     * 默认大小 50M
     */
    public static final long DEFAULT_MAX_SIZE = 50 * 1024 * 1024;

    /**
     * 默认的文件名最大长度 100
     */
    public static final int DEFAULT_FILE_NAME_LENGTH = 100;

    /**
     * 默认上传的地址
     */
    private static String defaultBaseDir = RuoYiConfig.getProfile();

    public static void setDefaultBaseDir(String defaultBaseDir)
    {
        FileUploadUtils.defaultBaseDir = defaultBaseDir;
    }

    public static String getDefaultBaseDir()
    {
        return defaultBaseDir;
    }

    /**
     * 以默认配置进行文件上传
     *
     * @param file 上传的文件
     * @return 文件名称
     * @throws Exception
     */
    public static final String upload(MultipartFile file) throws IOException
    {
        try
        {
            return upload(getDefaultBaseDir(), file, com.dechnic.common.utils.file.MimeTypeUtils.DEFAULT_ALLOWED_EXTENSION);
        }
        catch (Exception e)
        {
            throw new IOException(e.getMessage(), e);
        }
    }

    /**
     * 根据文件路径上传
     *
     * @param baseDir 相对应用的基目录
     * @param file 上传的文件
     * @return 文件名称
     * @throws IOException
     */
    public static final String upload(String baseDir, MultipartFile file) throws IOException
    {
        try
        {
            return upload(baseDir, file, com.dechnic.common.utils.file.MimeTypeUtils.DEFAULT_ALLOWED_EXTENSION);
        }
        catch (Exception e)
        {
            throw new IOException(e.getMessage(), e);
        }
    }

    /**
     * 文件上传
     *
     * @param baseDir 相对应用的基目录
     * @param file 上传的文件
     * @param allowedExtension 上传文件类型
     * @return 返回上传成功的文件名
     * @throws FileSizeLimitExceededException 如果超出最大大小
     * @throws FileNameLengthLimitExceededException 文件名太长
     * @throws IOException 比如读写文件出错时
     * @throws InvalidExtensionException 文件校验异常
     */
    public static final String upload(String baseDir, MultipartFile file, String[] allowedExtension)
            throws FileSizeLimitExceededException, IOException, FileNameLengthLimitExceededException,
            InvalidExtensionException
    {
        int fileNamelength = Objects.requireNonNull(file.getOriginalFilename()).length();
        if (fileNamelength > FileUploadUtils.DEFAULT_FILE_NAME_LENGTH)
        {
            throw new FileNameLengthLimitExceededException(FileUploadUtils.DEFAULT_FILE_NAME_LENGTH);
        }

        assertAllowed(file, allowedExtension);

        String fileName = extractFilename(file);

        String absPath = getAbsoluteFile(baseDir, fileName).getAbsolutePath();
        file.transferTo(Paths.get(absPath));
        return getPathFileName(baseDir, fileName);
    }

    /**
     * 编码文件名
     */
    public static final String extractFilename(MultipartFile file)
    {
        return StringUtils.format("{}/{}_{}.{}", DateUtils.datePath(),
                FilenameUtils.getBaseName(file.getOriginalFilename()), Seq.getId(Seq.uploadSeqType), getExtension(file));
    }

    public static final File getAbsoluteFile(String uploadDir, String fileName) throws IOException
    {
        File desc = new File(uploadDir + File.separator + fileName);

        if (!desc.exists())
        {
            if (!desc.getParentFile().exists())
            {
                desc.getParentFile().mkdirs();
            }
        }
        return desc;
    }

    public static final String getPathFileName(String uploadDir, String fileName) throws IOException
    {
        int dirLastIndex = RuoYiConfig.getProfile().length() + 1;
        String currentDir = StringUtils.substring(uploadDir, dirLastIndex);
        return Constants.RESOURCE_PREFIX + "/" + currentDir + "/" + fileName;
    }

    /**
     * 文件大小校验
     *
     * @param file 上传的文件
     * @return
     * @throws FileSizeLimitExceededException 如果超出最大大小
     * @throws InvalidExtensionException
     */
    public static final void assertAllowed(MultipartFile file, String[] allowedExtension)
            throws FileSizeLimitExceededException, InvalidExtensionException
    {
        long size = file.getSize();
        if (size > DEFAULT_MAX_SIZE)
        {
            throw new FileSizeLimitExceededException(DEFAULT_MAX_SIZE / 1024 / 1024);
        }

        String fileName = file.getOriginalFilename();
        String extension = getExtension(file);
        if (allowedExtension != null && !isAllowedExtension(extension, allowedExtension))
        {
            if (allowedExtension == com.dechnic.common.utils.file.MimeTypeUtils.IMAGE_EXTENSION)
            {
                throw new InvalidExtensionException.InvalidImageExtensionException(allowedExtension, extension,
                        fileName);
            }
            else if (allowedExtension == com.dechnic.common.utils.file.MimeTypeUtils.FLASH_EXTENSION)
            {
                throw new InvalidExtensionException.InvalidFlashExtensionException(allowedExtension, extension,
                        fileName);
            }
            else if (allowedExtension == com.dechnic.common.utils.file.MimeTypeUtils.MEDIA_EXTENSION)
            {
                throw new InvalidExtensionException.InvalidMediaExtensionException(allowedExtension, extension,
                        fileName);
            }
            else if (allowedExtension == com.dechnic.common.utils.file.MimeTypeUtils.VIDEO_EXTENSION)
            {
                throw new InvalidExtensionException.InvalidVideoExtensionException(allowedExtension, extension,
                        fileName);
            }
            else
            {
                throw new InvalidExtensionException(allowedExtension, extension, fileName);
            }
        }
    }

    /**
     * 判断MIME类型是否是允许的MIME类型
     *
     * @param extension
     * @param allowedExtension
     * @return
     */
    public static final boolean isAllowedExtension(String extension, String[] allowedExtension)
    {
        for (String str : allowedExtension)
        {
            if (str.equalsIgnoreCase(extension))
            {
                return true;
            }
        }
        return false;
    }

    /**
     * 获取文件名的后缀
     *
     * @param file 表单文件
     * @return 后缀名
     */
    public static final String getExtension(MultipartFile file)
    {
        String extension = FilenameUtils.getExtension(file.getOriginalFilename());
        if (StringUtils.isEmpty(extension))
        {
            extension = com.dechnic.common.utils.file.MimeTypeUtils.getExtension(Objects.requireNonNull(file.getContentType()));
        }
        return extension;
    }
}

2.图片下载

1. 前端vue2

 <el-table-column label="小程序二维码" align="center" prop="wchatQr" >
    <template slot-scope="scope">
      <el-link  @click="downloadQrImg(scope.row.wchatQr)" >
        <img
          :src="scope.row.wchatQr"
          style="display: block; max-width: 100%; margin: 0 auto"
        />
      </el-link>
    </template>

  </el-table-column>

  //下载小程序二维码
    downloadQrImg(qrUrl){
      console.log("qrUrl:"+qrUrl.substring(this.serverUrl.length,qrUrl.length));
      download.resource(qrUrl);
    }

download.js

import axios from 'axios'
import { Message } from 'element-ui'
import { saveAs } from 'file-saver'
import { getToken } from '@/utils/auth'
import errorCode from '@/utils/errorCode'
import { blobValidate } from "@/utils/ruoyi";
import {globalConfig} from "../../public/config";

const baseURL = process.env.NODE_ENV === "production" ?globalConfig.reqUrl : process.env.VUE_APP_BASE_API

export default {
  name(name, isDelete = true) {
    var url = baseURL + "/common/download?fileName=" + encodeURI(name) + "&delete=" + isDelete
    axios({
      method: 'get',
      url: url,
      responseType: 'blob',
      headers: { 'Authorization': 'Bearer ' + getToken() }
    }).then(async (res) => {
      const isLogin = await blobValidate(res.data);
      if (isLogin) {
        const blob = new Blob([res.data])
        this.saveAs(blob, decodeURI(res.headers['download-filename']))
      } else {
        this.printErrMsg(res.data);
      }
    })
  },
  resource(resource) {
    var url = baseURL + "/common/download/resource?resource=" + encodeURI(resource);
    axios({
      method: 'get',
      url: url,
      responseType: 'blob',
      headers: { 'Authorization': 'Bearer ' + getToken() }
    }).then(async (res) => {
      const isLogin = await blobValidate(res.data);
      if (isLogin) {
        const blob = new Blob([res.data])
        this.saveAs(blob, decodeURI(res.headers['download-filename']))
      } else {
        this.printErrMsg(res.data);
      }
    })
  },
  zip(url, name) {
    var url = baseURL + url
    axios({
      method: 'get',
      url: url,
      responseType: 'blob',
      headers: { 'Authorization': 'Bearer ' + getToken() }
    }).then(async (res) => {
      const isLogin = await blobValidate(res.data);
      if (isLogin) {
        const blob = new Blob([res.data], { type: 'application/zip' })
        this.saveAs(blob, name)
      } else {
        this.printErrMsg(res.data);
      }
    })
  },
  saveAs(text, name, opts) {
    saveAs(text, name, opts);
  },
  async printErrMsg(data) {
    const resText = await data.text();
    const rspObj = JSON.parse(resText);
    const errMsg = errorCode[rspObj.code] || rspObj.msg || errorCode['default']
    Message.error(errMsg);
  }
}

2. 后端代码
   CommonController.java

import axios from 'axios'
import { Message } from 'element-ui'
import { saveAs } from 'file-saver'
import { getToken } from '@/utils/auth'
import errorCode from '@/utils/errorCode'
import { blobValidate } from "@/utils/ruoyi";
import {globalConfig} from "../../public/config";

const baseURL = process.env.NODE_ENV === "production" ?globalConfig.reqUrl : process.env.VUE_APP_BASE_API

export default {
  name(name, isDelete = true) {
    var url = baseURL + "/common/download?fileName=" + encodeURI(name) + "&delete=" + isDelete
    axios({
      method: 'get',
      url: url,
      responseType: 'blob',
      headers: { 'Authorization': 'Bearer ' + getToken() }
    }).then(async (res) => {
      const isLogin = await blobValidate(res.data);
      if (isLogin) {
        const blob = new Blob([res.data])
        this.saveAs(blob, decodeURI(res.headers['download-filename']))
      } else {
        this.printErrMsg(res.data);
      }
    })
  },
  resource(resource) {
    var url = baseURL + "/common/download/resource?resource=" + encodeURI(resource);
    axios({
      method: 'get',
      url: url,
      responseType: 'blob',
      headers: { 'Authorization': 'Bearer ' + getToken() }
    }).then(async (res) => {
      const isLogin = await blobValidate(res.data);
      if (isLogin) {
        const blob = new Blob([res.data])
        this.saveAs(blob, decodeURI(res.headers['download-filename']))
      } else {
        this.printErrMsg(res.data);
      }
    })
  },
  zip(url, name) {
    var url = baseURL + url
    axios({
      method: 'get',
      url: url,
      responseType: 'blob',
      headers: { 'Authorization': 'Bearer ' + getToken() }
    }).then(async (res) => {
      const isLogin = await blobValidate(res.data);
      if (isLogin) {
        const blob = new Blob([res.data], { type: 'application/zip' })
        this.saveAs(blob, name)
      } else {
        this.printErrMsg(res.data);
      }
    })
  },
  saveAs(text, name, opts) {
    saveAs(text, name, opts);
  },
  async printErrMsg(data) {
    const resText = await data.text();
    const rspObj = JSON.parse(resText);
    const errMsg = errorCode[rspObj.code] || rspObj.msg || errorCode['default']
    Message.error(errMsg);
  }
}

FileUtils.java

package com.dechnic.common.utils.file;

import com.dechnic.common.config.RuoYiConfig;
import com.dechnic.common.utils.DateUtils;
import com.dechnic.common.utils.StringUtils;
import com.dechnic.common.utils.uuid.IdUtils;
import org.apache.commons.io.FilenameUtils;
import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.ArrayUtils;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;

/**
 * 文件处理工具类
 *
 * @author ruoyi
 */
public class FileUtils
{
    public static String FILENAME_PATTERN = "[a-zA-Z0-9_\\-\\|\\.\\u4e00-\\u9fa5]+";

    /**
     * 输出指定文件的byte数组
     *
     * @param filePath 文件路径
     * @param os 输出流
     * @return
     */
    public static void writeBytes(String filePath, OutputStream os) throws IOException
    {
        FileInputStream fis = null;
        try
        {
            File file = new File(filePath);
            if (!file.exists())
            {
                throw new FileNotFoundException(filePath);
            }
            fis = new FileInputStream(file);
            byte[] b = new byte[1024];
            int length;
            while ((length = fis.read(b)) > 0)
            {
                os.write(b, 0, length);
            }
        }
        catch (IOException e)
        {
            throw e;
        }
        finally
        {
            IOUtils.close(os);
            IOUtils.close(fis);
        }
    }

    /**
     * 写数据到文件中
     *
     * @param data 数据
     * @return 目标文件
     * @throws IOException IO异常
     */
    public static String writeImportBytes(byte[] data) throws IOException
    {
        return writeBytes(data, RuoYiConfig.getImportPath());
    }

    /**
     * 写数据到文件中
     *
     * @param data 数据
     * @param uploadDir 目标文件
     * @return 目标文件
     * @throws IOException IO异常
     */
    public static String writeBytes(byte[] data, String uploadDir) throws IOException
    {
        FileOutputStream fos = null;
        String pathName = "";
        try
        {
            String extension = getFileExtendName(data);
            pathName = DateUtils.datePath() + "/" + IdUtils.fastUUID() + "." + extension;
            File file = com.dechnic.common.utils.file.FileUploadUtils.getAbsoluteFile(uploadDir, pathName);
            fos = new FileOutputStream(file);
            fos.write(data);
        }
        finally
        {
            IOUtils.close(fos);
        }
        return com.dechnic.common.utils.file.FileUploadUtils.getPathFileName(uploadDir, pathName);
    }

    /**
     * 删除文件
     *
     * @param filePath 文件
     * @return
     */
    public static boolean deleteFile(String filePath)
    {
        boolean flag = false;
        File file = new File(filePath);
        // 路径为文件且不为空则进行删除
        if (file.isFile() && file.exists())
        {
            file.delete();
            flag = true;
        }
        return flag;
    }

    /**
     * 文件名称验证
     *
     * @param filename 文件名称
     * @return true 正常 false 非法
     */
    public static boolean isValidFilename(String filename)
    {
        return filename.matches(FILENAME_PATTERN);
    }

    /**
     * 检查文件是否可下载
     *
     * @param resource 需要下载的文件
     * @return true 正常 false 非法
     */
    public static boolean checkAllowDownload(String resource)
    {
        // 禁止目录上跳级别
        if (StringUtils.contains(resource, ".."))
        {
            return false;
        }

        // 检查允许下载的文件规则
        if (ArrayUtils.contains(com.dechnic.common.utils.file.MimeTypeUtils.DEFAULT_ALLOWED_EXTENSION, com.dechnic.common.utils.file.FileTypeUtils.getFileType(resource)))
        {
            return true;
        }

        // 不在允许下载的文件规则
        return false;
    }

    /**
     * 下载文件名重新编码
     *
     * @param request 请求对象
     * @param fileName 文件名
     * @return 编码后的文件名
     */
    public static String setFileDownloadHeader(HttpServletRequest request, String fileName) throws UnsupportedEncodingException
    {
        final String agent = request.getHeader("USER-AGENT");
        String filename = fileName;
        if (agent.contains("MSIE"))
        {
            // IE浏览器
            filename = URLEncoder.encode(filename, "utf-8");
            filename = filename.replace("+", " ");
        }
        else if (agent.contains("Firefox"))
        {
            // 火狐浏览器
            filename = new String(fileName.getBytes(), "ISO8859-1");
        }
        else if (agent.contains("Chrome"))
        {
            // google浏览器
            filename = URLEncoder.encode(filename, "utf-8");
        }
        else
        {
            // 其它浏览器
            filename = URLEncoder.encode(filename, "utf-8");
        }
        return filename;
    }

    /**
     * 下载文件名重新编码
     *
     * @param response 响应对象
     * @param realFileName 真实文件名
     */
    public static void setAttachmentResponseHeader(HttpServletResponse response, String realFileName) throws UnsupportedEncodingException
    {
        String percentEncodedFileName = percentEncode(realFileName);

        StringBuilder contentDispositionValue = new StringBuilder();
        contentDispositionValue.append("attachment; filename=")
                .append(percentEncodedFileName)
                .append(";")
                .append("filename*=")
                .append("utf-8''")
                .append(percentEncodedFileName);

        response.addHeader("Access-Control-Expose-Headers", "Content-Disposition,download-filename");
        response.setHeader("Content-disposition", contentDispositionValue.toString());
        response.setHeader("download-filename", percentEncodedFileName);
    }

    /**
     * 百分号编码工具方法
     *
     * @param s 需要百分号编码的字符串
     * @return 百分号编码后的字符串
     */
    public static String percentEncode(String s) throws UnsupportedEncodingException
    {
        String encode = URLEncoder.encode(s, StandardCharsets.UTF_8.toString());
        return encode.replaceAll("\\+", "%20");
    }

    /**
     * 获取图像后缀
     *
     * @param photoByte 图像数据
     * @return 后缀名
     */
    public static String getFileExtendName(byte[] photoByte)
    {
        String strFileExtendName = "jpg";
        if ((photoByte[0] == 71) && (photoByte[1] == 73) && (photoByte[2] == 70) && (photoByte[3] == 56)
                && ((photoByte[4] == 55) || (photoByte[4] == 57)) && (photoByte[5] == 97))
        {
            strFileExtendName = "gif";
        }
        else if ((photoByte[6] == 74) && (photoByte[7] == 70) && (photoByte[8] == 73) && (photoByte[9] == 70))
        {
            strFileExtendName = "jpg";
        }
        else if ((photoByte[0] == 66) && (photoByte[1] == 77))
        {
            strFileExtendName = "bmp";
        }
        else if ((photoByte[1] == 80) && (photoByte[2] == 78) && (photoByte[3] == 71))
        {
            strFileExtendName = "png";
        }
        return strFileExtendName;
    }

    /**
     * 获取文件名称 /profile/upload/2022/04/16/ruoyi.png -- ruoyi.png
     *
     * @param fileName 路径名称
     * @return 没有文件路径的名称
     */
    public static String getName(String fileName)
    {
        if (fileName == null)
        {
            return null;
        }
        int lastUnixPos = fileName.lastIndexOf('/');
        int lastWindowsPos = fileName.lastIndexOf('\\');
        int index = Math.max(lastUnixPos, lastWindowsPos);
        return fileName.substring(index + 1);
    }

    /**
     * 获取不带后缀文件名称 /profile/upload/2022/04/16/ruoyi.png -- ruoyi
     *
     * @param fileName 路径名称
     * @return 没有文件路径和后缀的名称
     */
    public static String getNameNotSuffix(String fileName)
    {
        if (fileName == null)
        {
            return null;
        }
        String baseName = FilenameUtils.getBaseName(fileName);
        return baseName;
    }

}