.NET 基礎連接已關閉: 傳送時發生未預期的錯誤。

串接API時一直出現錯誤

基礎連接已關閉: 傳送時發生未預期的錯誤。

上網查找資料後應該是SSL的問題，總之就是串接方已經不接受TLS1.0的協定，所以要強制讓我方以TLS1.1或1.2

需.NET4.0以上，記得先Imports System.Net才能用參數

之後再整個Request前先加上

ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12

就可以解決了，未來會不會需要更新成更高或其他的協議就未知啦

把Base64 轉成 Byte Array 後儲存為圖檔

專案需要將撈出來的HTML頁面產生PDF...慢慢刻太花時間外加CSS很容易跑掉，乾脆轉圖檔儲存，但用html2canvas轉完後是base64，只好轉存成byte再save圖檔給PDF用...紀錄一下參考的base64 to byte文章

 

HTML Markup

The following HTML Markup consists of an ASP.Net FileUpload control to upload the Image File and a Button control to trigger the File upload process.

<form id="form1" runat="server">

<asp:FileUpload ID="FileUpload1" runat="server" />

<asp:Button ID="btnUpload" runat="server" Text="Upload"

    onclick="btnUpload_Click" />

</form>

 

 

Convert Base64 string to Byte Array using C# and VB.Net

When the Upload button is clicked, the Image file is read into a Byte Array using the BinaryReader class object.

The Byte Array is then converted into Base64 encoded string using the Convert.ToBase64String method.

Now in order to save the Base64 encoded string as Image File, the Base64 encoded string is converted back to Byte Array using the Convert.FromBase64String function.

Finally the Byte Array is saved to Folder on Disk as File using WriteAllBytes method of the File class.

C#

protected void btnUpload_Click(object sender, EventArgs e)

{

    //***Convert Image File to Base64 Encoded string***//

 

    //Read the uploaded file using BinaryReader and convert it to Byte Array.

    BinaryReader br = new BinaryReader(FileUpload1.PostedFile.InputStream);

    byte[] bytes = br.ReadBytes((int)FileUpload1.PostedFile.InputStream.Length);

 

    //Convert the Byte Array to Base64 Encoded string.

    string base64String = Convert.ToBase64String(bytes, 0, bytes.Length);

 

    //***Save Base64 Encoded string as Image File***//

 

    //Convert Base64 Encoded string to Byte Array.

    byte[] imageBytes = Convert.FromBase64String(base64String);

       

    //Save the Byte Array as Image File.

    string filePath = Server.MapPath("~/Files/" + Path.GetFileName(FileUpload1.PostedFile.FileName));

    File.WriteAllBytes(filePath, imageBytes);

}

 

VB.Net

Protected Sub btnUpload_Click(sender As Object, e As EventArgs)

    '***Convert Image File to Base64 Encoded string***

 

    'Read the uploaded file using BinaryReader and convert it to Byte Array.

    Dim br As New BinaryReader(FileUpload1.PostedFile.InputStream)

    Dim bytes As Byte() = br.ReadBytes(CInt(FileUpload1.PostedFile.InputStream.Length))

 

    'Convert the Byte Array to Base64 Encoded string.

    Dim base64String As String = Convert.ToBase64String(bytes, 0, bytes.Length)

 

    '***Save Base64 Encoded string as Image File***

 

    'Convert Base64 Encoded string to Byte Array.

    Dim imageBytes As Byte() = Convert.FromBase64String(base64String)

 

    'Save the Byte Array as Image File.

    Dim filePath As String = Server.MapPath("~/Files/" + Path.GetFileName(FileUpload1.PostedFile.FileName))

    File.WriteAllBytes(filePath, imageBytes)

End Sub

 

點我到原文網址

.Net VB 圖片上傳後變橫的

爬了下文應該是因為exif資訊的問題，上傳前必須先判斷是否需要轉角度...找了一下總算找到相關內容參考

Public Function TestRotate(sImageFilePath As String) As Boolean
    Dim rft As RotateFlipType = RotateFlipType.RotateNoneFlipNone
    Dim img As Bitmap = Image.FromFile(sImageFilePath)
    Dim properties As PropertyItem() = img.PropertyItems
    Dim bReturn As Boolean = False
    For Each p As PropertyItem In properties
      If p.Id = 274 Then
        Dim orientation As Short = BitConverter.ToInt16(p.Value, 0)
        Select Case orientation
          Case 1
            rft = RotateFlipType.RotateNoneFlipNone
          Case 3
            rft = RotateFlipType.Rotate180FlipNone
          Case 6
           rft = RotateFlipType.Rotate90FlipNone
          Case 8
           rft = RotateFlipType.Rotate270FlipNone
        End Select
      End If
    Next
    If rft <> RotateFlipType.RotateNoneFlipNone Then
      img.RotateFlip(rft)
      System.IO.File.Delete(sImageFilePath)
      img.Save(sImageFilePath, System.Drawing.Imaging.ImageFormat.Jpeg)
      bReturn = True
    End If
    Return bReturn

  End Function

需要import
System.Drawing
System.Drawing.Imaging

RotateFlipType還有很多種，但手機似乎只會遇到以上狀況所以就只用到1、3、6、8

感謝幫助到我的原文，那邊也有C#的寫法

原文網址點我

Null / DBNull / String.Empty的差異

找.net判斷null的東西時看到不錯的文章，但該文章已經失效只好自己紀錄一下...

以下是文章的紀錄：

Null跟DBNull及String.Empty這三者,或許很少有人認真的去想過這三者的差異在那,而什麼時候要用那一個去判斷?

從簡單的if去比對這三者是否相等,很快的就發現這三者是不相等的.

null != DBNull  /DBNull != string.Empty / null != string.Empty

那麼現在宣告了兩個變數,一個是string a="",另一個是string b=null; 那麼這兩個變數是各自符合那一種?

結果是

a != null;

a != DBNull

a = string.Empty

拿.Net 2.0才有的新判斷string.IsNullOrEmpty來看.也是為true

而b的部份則如下

b = null

b != dbnull

b != string.Empty

string.IsNullOrEmpty(b) = true

從這兩個例子看到什麼時候是Null,什麼時候是string.Empty,那麼DBNull呢?

DBNull的使用時機,當至資料庫查詢,符合的資料回傳的資料欄位沒有值,為null時,此時此欄位的值就=DBNull.

當至資料庫查詢,沒有符合的資料回傳時,此時回傳的結果就=Null.



Null是當物件未被初始化時的情況,例如 StreamReader reader;還沒有給new StreamReader();

ex :
object o=cmd.ExecuteScalar();(回傳一個欄位的值)
狀況1:當DB回傳有符合的資料,但該欄位沒有值時.o = DBNull 可是 o != null
狀況2:當DB回傳沒有符合的資料時, o = null可是o != DBNull
狀況3:不論是狀況1或狀況2的結果,Convert.ToString(o)=string.Empty;


感謝原作者的文章，雖然連結已失效還是貼下
https://www.dotblogs.com.tw/jeff-yeh/archive/2008/12/07/6286.aspx