使用 OleDb 以只讀模式打開 Excel 文件？

Question

我們有一些代碼可以打開 Excel（XLSX 和 XLS）文件並從中加載數據。 我們將 OleDbConnection 與 Microsoft Access 數據庫引擎 (ACE) 結合使用。

當有問題的 Excel 文件位於網絡共享上並且用戶在 Excel 中打開該文件時，有時此代碼會引發異常。 我着手嘗試解決這個問題，我的假設是我可以將一個設置添加到連接字符串以配置只讀訪問。

在我的研究中，我發現這個問題多次提出，並用各種推薦的解決方案進行了回答。 不幸的是，我發現它們都不起作用，而且我找不到任何關於 Excel 連接字符串設置的官方 Microsoft 文檔。

我開始認為我想做的事情是不可能的，並且會很感激任何幫助。

這是我的測試代碼：

const string excelFile = @"\\server\folder\file.xlsx";

var connStrings = new[] {
    // Base, no "read only" configuration
    $"Provider=Microsoft.ACE.OLEDB.12.0;Data Source={excelFile};Extended Properties=\"Excel 12.0;IMEX=1\"",

    // Mode=Read
    //
    // C# ace oledb 12 read-only file
    // https://stackoverflow.com/questions/45165570/c-sharp-ace-oledb-12-read-only-file
    //
    // OleDbConnection Read Only Mode
    // https://social.msdn.microsoft.com/Forums/office/en-US/498cd52a-b0ee-4c8d-8943-2b76055b4130/oledbconnection-read-only-mode?forum=accessdev
    $"Provider=Microsoft.ACE.OLEDB.12.0;Mode=Read;Data Source={excelFile};Extended Properties=\"Excel 12.0;IMEX=1\"",

    // READONLY=TRUE (and variations) in Extended Properties
    //
    // Excel source read only?
    // https://social.msdn.microsoft.com/Forums/sqlserver/en-US/d03e4b1a-6be0-4b3c-8b31-42d6fc79bf39/excel-source-read-only?forum=sqlintegrationservices
    //
    // Working with MS Excel(xls / xlsx) Using MDAC and Oledb
    // https://www.codeproject.com/Articles/37055/Working-with-MS-Excel-xls-xlsx-Using-MDAC-and-Oled
    $"Provider=Microsoft.ACE.OLEDB.12.0;Data Source={excelFile};Extended Properties=\"Excel 12.0;IMEX=1;READONLY=TRUE\"",
    $"Provider=Microsoft.ACE.OLEDB.12.0;Data Source={excelFile};Extended Properties=\"Excel 12.0;IMEX=1;ReadOnly=true;\"",
    $"Provider=Microsoft.ACE.OLEDB.12.0;Data Source={excelFile};Extended Properties=\"Excel 12.0;IMEX=1;MODE=READ;READONLY=TRUE\"",

    // Wild guesses
    $"Provider=Microsoft.ACE.OLEDB.12.0;Data Source={excelFile};Extended Properties=\"Excel 12.0;IMEX=1;READONLY=1\"",
    $"Provider=Microsoft.ACE.OLEDB.12.0;Data Source={excelFile};Extended Properties=\"Excel 12.0;IMEX=1;MODE=READ;READONLY=1\""
};

for ( var i = 0; i < connStrings.Length; i++ ) {
    var conn = new OleDbConnection( connStrings[i] );

    try {
        conn.Open();
        Console.WriteLine( $"{i}: Success" );
        conn.Close();
    }
    catch ( OleDbException ex ) {
        Console.WriteLine( $"{i}: FAIL: {ex.Message}" );
    }
    finally {
        conn.Dispose();
    }
}

當目標文件在網絡共享的 Excel 中打開時，所有連接字符串變體都會失敗，如下所示：

0: FAIL: The Microsoft Access database engine cannot open or write to the file ''. It is already opened exclusively by another user, or you need permission to view and write its data.
1: FAIL: The Microsoft Access database engine cannot open or write to the file ''. It is already opened exclusively by another user, or you need permission to view and write its data.
2: FAIL: The Microsoft Access database engine cannot open or write to the file ''. It is already opened exclusively by another user, or you need permission to view and write its data.
3: FAIL: The Microsoft Access database engine cannot open or write to the file ''. It is already opened exclusively by another user, or you need permission to view and write its data.
4: FAIL: The Microsoft Access database engine cannot open or write to the file ''. It is already opened exclusively by another user, or you need permission to view and write its data.
5: FAIL: The Microsoft Access database engine cannot open or write to the file ''. It is already opened exclusively by another user, or you need permission to view and write its data.
6: FAIL: The Microsoft Access database engine cannot open or write to the file ''. It is already opened exclusively by another user, or you need permission to view and write its data.

Answer 1

您可以創建該文件的副本以繞過只讀訪問。

嘗試使用System.IO命名空間中的File.Copy()方法將 Excel 復制到另一個位置，例如 C:/temp。

然后使用 OLEDB 打開它來讀取和關閉/刪除它