「C# 檔案不落地在記憶體操作」筆記
===

## 下載 URL 圖檔落地

using (WebClient webClient_ = new WebClient())
{
    webClient_.DownloadFile(imageURL, fileName);
}

## 下載 URL 圖檔到記憶體

using (WebClient webClient_ = new WebClient())
{
   byte[] data_ = webClient_.DownloadData(imageURL);
   MemoryStream mem_= new MemoryStream(data_);
}

## 寫入 PDF 檔案落地

using (FileStream wfs = new FileStream(filePath, FileMode.OpenOrCreate))
{
    PdfWriter wr_ = PdfWriter.GetInstance(_doc, wfs);
    _doc.Open();

    float[] clos = new float[] { 40, 40, 40 };// 寬度
    PdfPTable tablerow1 = new PdfPTable(clos);
    foreach (string t in title)
    {
        PdfPCell cell = new PdfPCell(new Paragraph(t))
        {
            MinimumHeight = 4f
        };
        tablerow1.AddCell(cell);
    }
    List<string> list = new List<string>()
    {
        "ABC",
        "cde",
        "FgH"
    };
    foreach (var d in list)
    {
        tablerow1.AddCell(new PdfPCell(image, true));
        tablerow1.AddCell(new PdfPCell(new Paragraph(d + d)));

        tablerow1.AddCell(new PdfPCell(new Paragraph(d)));
    }
    _doc.Add(tablerow1);//將表格添加到pdf文檔中
    _doc.Close();//關閉
    wr_.Close();
    wfs.Close();
}

## 寫入 PDF 檔案到記憶體

using (MemoryStream mem_ = new MemoryStream())
{
    PdfWriter wr_ = PdfWriter.GetInstance(_doc, mem_);

    _doc.Open();

    float[] clos = new float[] { 40, 40, 40 };// 寬度
    PdfPTable tablerow1 = new PdfPTable(clos);
    foreach (string t in title)
    {
        PdfPCell cell = new PdfPCell(new Paragraph(t))
        {
            MinimumHeight = 4f
        };
        tablerow1.AddCell(cell);
    }
    List<string> list = new List<string>()
    {
        "ABC",
        "cde",
        "FgH"
    };
    foreach (var d in list)
    {
        tablerow1.AddCell(new PdfPCell(image, true));
        tablerow1.AddCell(new PdfPCell(new Paragraph(d + d)));

        tablerow1.AddCell(new PdfPCell(new Paragraph(d)));
    }
    _doc.Add(tablerow1);//將表格添加到pdf文檔中
    _doc.Close();//關閉
    wr_.Close();
    return mem_.ToArray();
}

如果 MemoryStream 要再使用，必須先轉成 byte[]，之後再宣告 MemoryStream 來使用

Attachment a_ = new Attachment(new MemoryStream(ms_.ToArray()), ct);

透過 new MemoryStream(ms_.ToArray()) 後，Attachment a_ 才能真正取的檔案內容

###### tags: `工作紀錄`