Question

我正在编写代码来从excel文件中读取数据。早些时候，如果我已经打开Excel文件，我的代码就进入了Catch（）＆＃39;阻止，并为它抛出一个例外。现在，它不会抛出异常，但需要很长时间才能阅读。我想知道为什么它没有进入＆＃39; Catch（）＆＃39;块。

代码：

DataTable VendorCodesTable = new DataTable("VendorCodesData");
DataTable ForSheetName = new DataTable("ForSheetName");
string SheetName = "Sheet1$";
try
{
    ExcelConnectionString = string.Format("Provider=Microsoft.Jet.OLEDB.4.0; data source={0}; Extended Properties=Excel 8.0;", fileName);
    OleDbConnection conn = new OleDbConnection();
    conn.ConnectionString = ExcelConnectionString;
    conn.Open();
    ForSheetName = conn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
    if (ForSheetName != null)
    {
        SheetName = ForSheetName.Rows[0]["TABLE_NAME"].ToString();
    }
    conn.Close();
    OleDbDataAdapter adapter = new OleDbDataAdapter("SELECT * FROM ["+SheetName+"]", ExcelConnectionString);
    adapter.Fill(VendorCodesTable);
}
catch (Exception ex)
{
    MessageBox.Show(ex.ToString(), "Exception");
}
return VendorCodesTable;

我添加了这段代码并且它停止了抛出错误，并且花费了很长时间来加载文件：

OleDbConnection conn = new OleDbConnection();
conn.ConnectionString = ExcelConnectionString;
conn.Open();
ForSheetName = conn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
if (ForSheetName != null)
{
    SheetName = ForSheetName.Rows[0]["TABLE_NAME"].ToString();
}
conn.Close();

现在，即使我对上面的行进行评论，它也不会进入＆＃39; Catch（）＆＃39;

Answer 1

如果文件打开，我不确定查询是否失败。也许只是等待...... 您可以像这样测试这种情况： VB.NEt代码：

Private Function FileIsReadable(Path As String) As Boolean
Dim RV As Boolean = True

'tests if the file is open. Returns true if the file is not opened by excel.

Dim stream As IO.FileStream = Nothing
Try
    stream = IO.File.Open(Path, IO.FileMode.Open, IO.FileAccess.ReadWrite, IO.FileShare.None)
Catch ex As Exception

    If TypeOf ex Is IO.IOException AndAlso IsFileLocked(ex) Then
        RV = False
    End If
Finally
    If IsNothing(stream) = False Then
        stream.Dispose()
    End If

End Try

Return RV

结束功能

从excel文件中读取数据：代码不会进入Catch（）块

1 个答案: