关于从httpservletrequest中获取图片

前端传了张图片到后台，request里面有图片，但存到list后list的size为0
怎样才能将request里的文件取出来

@RequestMapping("/picture")
public ResponseEntity uploadPicture(HttpServletRequest request, HttpServletResponse response) throws Exception {
//获取文件需要上传到的路径
String path = request.getRealPath("/upload") + "/";
File dir = new File(path);
if (!dir.exists()) {
dir.mkdir();
}
logger.debug("path=" + path);


request.setCharacterEncoding("utf-8"); //设置编码

DiskFileItemFactory factory = new DiskFileItemFactory();


factory.setRepository(dir);

factory.setSizeThreshold(1024 * 1024 * 1024 );

ServletFileUpload upload = new ServletFileUpload(factory);
//返回值设定
String ret="no result";
// List<FileItem> fileItemFromRequestList = getDataFromRequest(request);
try {
List<FileItem> list = upload.parseRequest(request);
FileItem picture = null;
System.out.println("i am here"+list);
for (FileItem item : list) {
//获取表单的属性名字
String name = item.getFieldName();
//如果获取的表单信息是普通的 文本 信息
if (item.isFormField()) {
//获取用户具体输入的字符串
String value = item.getString();
request.setAttribute(name, value);
logger.debug("name=" + name + ",value=" + value);
} else {
picture = item;
}
}