C# 最齐全的上传图片方法

方法里包括了图片大小限制、图片尺寸、文件内容等等的判断。。。

该案例是mvc下的demo，支持单张图片上传。

public actionresult upload()
    {
      string imgurl = "";
      foreach (string key in request.files)
      {
        //这里只测试上传第一张图片file[0]
        httppostedfilebase file0 = request.files[key];
        //转换成byte,读取图片mime类型
        stream stream;
        int size = file0.contentlength / 1024; //文件大小kb
        if (size > 1024)
        {
          return content(returnmsg(enum_return.失败, "图片不能超过1m：", null));
        }
        byte[] filebyte = new byte[2];//contentlength，这里我们只读取文件长度的前两位用于判断就好了，这样速度比较快，剩下的也用不到。
        stream = file0.inputstream;
       stream.read(filebyte, 0, 2);//contentlength，还是取前两位
        //获取图片宽和高
        //system.drawing.image image = system.drawing.image.fromstream(stream);
        //int width = image.width;
        //int height = image.height;
        string fileflag = "";
        if (filebyte != null && filebyte.length > 0)//图片数据是否为空
        {
          fileflag = filebyte[0].tostring()  filebyte[1].tostring();
        }
        string[] filetypestr = { "255216", "7173", "6677", "13780" };//对应的图片格式jpg,gif,bmp,png
        if (filetypestr.contains(fileflag))
        {
          string action = request["action"];
          string path = "/uploads/";
          switch (action)
          {
            case "headimage":
              path  = "headimage/";
              break;
            case "blogtype":
              path  = "blogtype/";
              break;
          }
          string fullpath = path  userinfo.userid  "/";
          if (!directory.exists(server.mappath(fullpath)))
          {
            directory.createdirectory(server.mappath(fullpath));
          }
          request.files[key].saveas(server.mappath(fullpath  request.files[key].filename));
          imgurl = fullpath  request.files[key].filename;
        }
        else
        {
          return content(returnmsg(enum_return.失败, "图片格式不正确：" fileflag, null));
        }
        stream.close();
      }
      return content(returnmsg(enum_return.成功, "上传成功", imgurl));
    }

一般处理程序

public void processrequest(httpcontext context)
  {
    context.response.contenttype = "application/json";
    httppostedfile _upfile = context.request.files["file"];
    if (_upfile.contentlength < 500000)
    {
      if (string.isnullorempty(_upfile.filename))
      {
         context.response.write("请上传图片");
      }
      string filefullname = _upfile.filename;
      string dataname = datetime.now.tostring("yyyymmddhhmmss");
      string filename = filefullname.substring(filefullname.lastindexof("\\")  1);
      string type = filefullname.substring(filefullname.lastindexof(".")  1);
      if (type == "bmp" || type == "jpg" || type == "gif" || type == "jpg" || type == "bmp" || type == "gif")
      {
        _upfile.saveas(httpcontext.current.server.mappath("photo")  "\\"  dataname  "."  type);
        httpcookie cookie = new httpcookie("photo");
        context.response.write("上传成功");
      }
      else
      {
        context.response.write("支持格式：|jpg|gif|bmp|");
      }
    }
    else
    {
      context.response.write("你的图片已经超过500k的大小！");
    }
  }

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