• 获取项目webapp文件下真实路径

//获取到了xxx在webapp下真实的路径
String path =request.getSession().getServletContextPath().getRealPath("xxx");

• 判断文件/文件夹是否存在

file.exist(); 存在为true 不存在为false

• 创建文件的所有不存在的根级目录

file.mkdirs();

• 使用springmvc上传文件

//spring-mvc.xml
 <!--文件上传-->
    <bean id="multipartResolver"
          class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <property name="defaultEncoding" value="utf-8"></property>
        <property name="maxUploadSize" value="10485760000"></property>
        <property name="maxInMemorySize" value="40960"></property>
    </bean>
    <!--文件上传-->


//FileUploadController
 @RequestMapping("upload")
@ResponseBody
    public Object upload(@RequestParam(value = "file", required = false) MultipartFile file, HttpServletRequest request) {
//        获取服务端webapp下真实路径
        String path = request.getSession().getServletContext().getRealPath("upload");
        Date currentDate = new Date();
//        文件夹日期格式
        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
        File fileDir = new File(path, dateFormat.format(currentDate));
//        获取文件类型
        String originalFilename = file.getOriginalFilename();
        String fileType = originalFilename.substring(originalFilename.lastIndexOf("."));
//        文件名
        String fileName = Long.toString(currentDate.getTime()) + fileType;
        File targetFile = new File(fileDir, fileName);
        if (!fileDir.exists()) {
            fileDir.mkdirs();
        }
        try {
            if(!targetFile.exists())file.transferTo(targetFile);
        } catch (IOException e) {
            e.printStackTrace();
            return new Ret.Builder(RetCode.ERROR).msg("上传失败");
        }
        return new Ret.Builder(RetCode.SUCCESS).msg("上传成功");
    }
}