前台vue代码

 <el-upload class="upload-demo" action="http://localhost:8080/Graduation_war_exploded/file/picture2"
            :on-preview="handlePreview" :on-remove="handleRemove" :before-remove="beforeRemove"
            :on-cxceed="handleExceed" :on-success="handleSuccess" :on-error="handleError" multiple :limit="3"
            accept="image/jpeg,image/png" :file-list="fileList">
            <el-button size="small" type="primary">点击上传</el-button>
            <div slot="tip">只能上传jpg/png文件，且不超过500kb</div>
          </el-upload>

data(){
return{
    fileList: []
}
methods:{
      handleSuccess() {
        this.$message.success("图片上传成功")
      },
      handleError() {
        this.$message.error("图片上传失败")
      },
      handleRemove(file, fileList) {
        console.log(file, fileList);
      },
      handlePreview(file) {
        console.log(file);
      },
      handleExceed(files, fileList) {
        this.$message.warning(`当前限制选择 3 个文件，本次选择了 ${files.length} 个文件，共选择了 ${files.length + fileList.length} 个文件`);
      },
      beforeRemove(file, fileList) {
        return this.$confirm(`确定移除 ${ file.name }？`);
      }
}

后台java代码

 @PostMapping(value = "picture2")
 @ResponseBody
 public Response uploadFile2(HttpServletRequest request, @RequestParam(value = "file", required = false) MultipartFile file) throws IOException {
     System.out.println("执行upload,执行图片上传");
     System.out.println(file);
     request.setCharacterEncoding("UTF-8");
     // String user = request.getParameter("user");
     if (!file.isEmpty()) {
         System.out.println("成功获取照片");
         String fileName = file.getOriginalFilename();
         String path = null;
         String type = null;
         type = fileName.indexOf(".") != -1 ? fileName.substring(fileName.lastIndexOf(".") + 1, fileName.length()) : null;
         System.out.println("图片初始名称为：" + fileName + " 类型为：" + type);
         if (type != null) {
             if ("GIF".equals(type.toUpperCase()) || "PNG".equals(type.toUpperCase()) || "JPG".equals(type.toUpperCase())) {
                 // 项目在容器中实际发布运行的根路径
                 // String SavefilePath = "D:/images/";
                 // 自定义的文件名称
                 String trueFileName = String.valueOf(System.currentTimeMillis()) + fileName;
                 // 设置存放图片文件的路径
                 path = SavefilePath + trueFileName;
                 System.out.println("存放图片文件的路径:" + path);
                 file.transferTo(new File(path));
                 System.out.println("文件成功上传到指定目录下");
                 return new Response(200, true, "上传文件成功", trueFileName);
             } else {
                 System.out.println("不是我们想要的文件类型,请按要求重新上传");
                 return new Response(201, false, "不是我们想要的文件类型,请按要求重新上传", null);
             }
         } else {
             System.out.println("文件类型为空");
             return new Response(201, false, "文件类型为空", null);
         }
     } else {
         System.out.println("没有找到相对应的文件");
         return new Response(201, false, "没有找到相对应的文件", null);
     }

 }