通過從SQL File流中獲取文件，使用ICSharpCode.SharpZipLib.Zip壓縮文件

Question

我正在使用ICSharpCode.SharpZipLib.Zip壓縮文件並下載zip文件，這里使用SQL File流存儲任何類型的文件（任意數量的GB）。 然后，我如何從sql文件流中壓縮文件並下載...我嘗試了以下類似操作，它引發了一個異常“大小為845941，但我希望ICSharpCode.SharpZipLib.Zip.ZipOutputStream.CloseEntry（ ）”。如何解決此問題...

string zipFileName = "ZipName.zip";
Response.ContentType = "application/zip";
Response.AddHeader("content-disposition", "fileName=" + zipFileName);
byte[] buffer = new byte[4096];
ZipOutputStream zipOutputStream = new ZipOutputStream(Response.OutputStream);
zipOutputStream.SetLevel(3);

string cs = System.Configuration.ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString;
foreach (Filec file1 in Files)
 {
   StreamModel model123 = new StreamModel();
   const string SelectTSql = @"
        SELECT FileData.PathName(), GET_FILESTREAM_TRANSACTION_CONTEXT(), FileType
         FROM MyFiles WHERE FileId = @FileId";

   using (TransactionScope ts = new TransactionScope())
    {
     using (System.Data.SqlClient.SqlConnection conn = new System.Data.SqlClient.SqlConnection(cs))
     {
      conn.Open();

      using (System.Data.SqlClient.SqlCommand cmd = new System.Data.SqlClient.SqlCommand(SelectTSql, conn))
       {
        cmd.Parameters.Add("@FileId", System.Data.SqlDbType.Int).Value = Convert.ToInt32(file1.FileId);
        using (System.Data.SqlClient.SqlDataReader rdr = cmd.ExecuteReader())
         {
           rdr.Read();
           model123.serverPath = rdr.GetSqlString(0).Value;
           model123.serverTxn = rdr.GetSqlBinary(1).Value;
           model123.filetype = rdr.GetSqlString(2).Value;
           rdr.Close();
         }
        }
      }
 ZipEntry zipEntry = new ZipEntry(ZipEntry.CleanName(file1.FileName));
 zipEntry.Size = model123.serverTxn.Length;
 zipOutputStream.PutNextEntry(zipEntry);
 byte[] buffer3 = new byte[4096];
 using (System.Data.SqlTypes.SqlFileStream sfs = new System.Data.SqlTypes.SqlFileStream(model123.serverPath, model123.serverTxn, FileAccess.Read))
  {
    int bytesRead;
    while ((bytesRead = sfs.Read(buffer3, 0, buffer3.Length)) > 0)
      {
         zipOutputStream.Write(buffer3, 0, bytesRead);
      }
    sfs.Close();
  }
 zipOutputStream.CloseEntry(); // at this line throwing an exception.
 ts.Complete();
   }
}
zipOutputStream.Close();
Response.Flush();
Response.End();

Answer 1

在理解了每一行代碼之后，我想出了解決方案。

1）“ zipEntry.Size = model123.serverTxn.Length;” 這行引起異常，因為“大小為845941，但我預期為16”。因為“ model123.serverTxn.Length”不是文件的完整大小，所以我將其更改為“ sfs.Length”，即SqlFileStream長度。

2）zipOutputStream級別最大設置為“ zipOutputStream.SetLevel（9）”，因為，我在這里像視頻一樣壓縮大型文件。

3）而且TransactionScope必須更大，否則，將不下載完整文件（大於500mb的大文件），因此下載后我們將看到文件損壞的錯誤消息。

string zipFileName = "ZipName.zip";
Response.ContentType = "application/zip";
Response.AddHeader("content-disposition", "fileName=" + zipFileName);
byte[] buffer = new byte[4096];
ZipOutputStream zipOutputStream = new ZipOutputStream(Response.OutputStream);
zipOutputStream.SetLevel(9);     // Point 2

try
 {
   string cs = System.Configuration.ConfigurationManager.ConnectionStrings["DefaultConnection"].ConnectionString;
   foreach (Filec file1 in Files)
    {
     StreamModel model123 = new StreamModel();
     const string SelectTSql = @"SELECT FileData.PathName(), GET_FILESTREAM_TRANSACTION_CONTEXT(), FileType
                         FROM MyFiles WHERE FileId = @FileId";
     using (TransactionScope ts = new TransactionScope(TransactionScopeOption.Required,
      new TransactionOptions { Timeout = TimeSpan.FromDays(1) })) // Point 3
        {
         using (System.Data.SqlClient.SqlConnection conn = new System.Data.SqlClient.SqlConnection(cs))
          {
            conn.Open();
          using (System.Data.SqlClient.SqlCommand cmd = new System.Data.SqlClient.SqlCommand(SelectTSql, conn))
           {
             cmd.Parameters.Add("@FileId", System.Data.SqlDbType.Int).Value = Convert.ToInt32(file1.FileId);
           using (System.Data.SqlClient.SqlDataReader rdr = cmd.ExecuteReader())
            {
              rdr.Read();
              model123.serverPath = rdr.GetSqlString(0).Value;
              model123.serverTxn = rdr.GetSqlBinary(1).Value;
              model123.filetype = rdr.GetSqlString(2).Value;
              rdr.Close();
            }
           }
          }
      using (System.Data.SqlTypes.SqlFileStream sfs = new System.Data.SqlTypes.SqlFileStream(model123.serverPath, model123.serverTxn, FileAccess.Read))
        {
          ZipEntry zipEntry = new ZipEntry(ZipEntry.CleanName(file1.FileName));
          zipEntry.Size = sfs.Length;      // Point 1
          zipOutputStream.PutNextEntry(zipEntry);
          int bytesRead;
          while ((bytesRead = sfs.Read(buffer, 0, buffer.Length)) > 0)
           {
            if (!Response.IsClientConnected)
              {
                  break;
              }
            zipOutputStream.Write(buffer, 0, bytesRead);
            Response.Flush();
           }
             sfs.Close();
         }

    ts.Complete();
  }
    zipOutputStream.CloseEntry();
 }

  zipOutputStream.Finish();
  zipOutputStream.Close();
  Response.Flush();
  Response.End();
}
catch (Exception ex)
 {
   TempData["ErrorMessage"] = "Oohhhh! Exception Occured(Error)...";
 }