public void UploadCategoryImage(string userID,string fileName,int fileLen,Stream fileData)
{
FileInfo fileInfo=new FileInfo(fileName);//重新命名
if(!fileInfo.Exists)//判断文件是否存在和长度是否大于规定长度
{
FileStream uploadFileStream = new FileStream(fileInfo.FullName,FileMode.CreateNew,FileAccess.Write);
byte[] fileDataB=new byte[fileLen];
int n=fileData.Read(fileDataB,0,fileLen);//读