c#读取excel数据

public static DataSet ToDataTable(string filePath, string filename, string tablename)
{
string connStr = "";
string fileType = System.IO.Path.GetExtension(filename);
if (string.IsNullOrEmpty(fileType)) return null;

        if (fileType == ".xls")
            connStr = "Provider=Microsoft.Jet.OLEDB.4.0;" + "Data Source=" + filePath + ";" + ";Extended Properties=\"Excel 8.0;HDR=YES;IMEX=1\"";
        else
            connStr = "Provider=Microsoft.ACE.OLEDB.12.0;" + "Data Source=" + filePath + ";" + ";Extended Properties=\"Excel 12.0;HDR=YES;IMEX=1\"";
        string sql_F = "Select * FROM [{0}]";

        OleDbConnection conn = null;
        OleDbDataAdapter da = null;
        DataTable dtSheetName = null;

        DataSet ds = new DataSet();
        try
        {
            // 初始化连接，并打开
            conn = new OleDbConnection(connStr);
            conn.Open();

            // 获取数据源的表定义元数据                        
            string SheetName = "";
            dtSheetName = conn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, new object[] { null, null, null, "TABLE" });

            // 初始化适配器
            da = new OleDbDataAdapter();
            for (int i = 0; i < dtSheetName.Rows.Count; i++)
            {
                SheetName = (string)dtSheetName.Rows[i]["TABLE_NAME"];

                if (SheetName.Contains("$") && !SheetName.Replace("'", "").EndsWith("$"))
                {
                    continue;
                }

                da.SelectCommand = new OleDbCommand(String.Format(sql_F, SheetName), conn);
                DataSet dsItem = new DataSet();
                da.Fill(dsItem, tablename);

                ds.Tables.Add(dsItem.Tables[0].Copy());
            }
        }
        catch (Exception ex)
        {
          //  MessageBox.Show(ex.Message);
           // throw ex;
        }
        finally
        {
            // 关闭连接
            if (conn.State == ConnectionState.Open)
            {
                conn.Close();
                da.Dispose();
                conn.Dispose();
            }
        }
        return ds;
    }