前端用的vue-element-ui，后端springboot，图片上传到本地的指定路径下，如：/usr/downloads/**
上传代码比较简单

@Override
    public String upload(HttpServletRequest request) {
        String fileName = "";
        try {
            Collection<Part> parts = request.getParts();
            for (Iterator<Part> iterator = parts.iterator(); iterator.hasNext(); ) {
                Part part = iterator.next();
                InputStream inputStream = part.getInputStream();
                String suffix = FileUtil.extName(part.getSubmittedFileName());
                fileName = RandomUtil.randomString(20) + "." + suffix;
                File dir = new File(this.path);
                if (!dir.exists()) {
                    dir.mkdirs();
                }
                path = this.path + fileName;

                IoUtil.copy(inputStream, new FileOutputStream(path), IoUtil.DEFAULT_BUFFER_SIZE);

            }
        } catch (Exception e) {
            throw new RRException("上传失败");
        }
        return fileName;
    }

在上传成功后，返回附件的新文件名，放到fileList中，用于el-upload回显

<el-upload
          :action="url"
          list-type="picture-card"
          :on-preview="handlePictureCardPreview"
          :on-remove="handleRemove"
          :on-success="handleSuccess"
          :limit="1"
          :headers="headers"
          :file-list="filesList"
        >
          <i class="el-icon-plus"></i>
        </el-upload>

如果url直接=新文件名或者文件的绝对路径，打开控制台，就会有404错误，它会在路径前面加上服务器地址，如下

http://localhost:8014//usr/downloads/**

这个时候就需要在后端做图片的静态映射，springboot如下，

@Configuration
public class CorsConfig implements WebMvcConfigurer {

    @Override
    public void addResourceHandlers(ResourceHandlerRegistry registry) {

        //Windows下
//        registry.addResourceHandler("/uploads2/**").addResourceLocations("file:D:/uploads2/");
        //Mac或Linux下(没有CDEF盘符)
        registry.addResourceHandler("/fileCall/**").addResourceLocations("file:/usr/downloads/");
    }
}

在修改前端图片的访问路径如下，

this.filesList.push({
                url: "/proxyApi/fileCall/" + data.tripCode.path,
              });

访问后台的时候就会映射到图片的实际路径下

http://localhost:8014/proxyApi/fileCall/pkit7zt792n9r2gcpve6.png

就可以获取到图片啦。