我寫的一個ExcelHelper通用類，可用於讀取或生成數據

讀取或生成EXCEL數據的方法有不少，通常常見的有：

1.經過OFFICE EXCEL組件，優勢：讀取與生成EXCEL文件方便，缺點：服務器上必須安裝OFFICE軟件，且進程沒法及時釋放

2.經過第三方組件（好比：NPOI），優勢：無需安裝OFFICE軟件，缺點：須要引入第三方組件，固然這個仍是比較強的

3.經過把EXCEL當成數據庫，鏈接後運用SQL語句讀取，寫入的話就自行拼接成HTML表格，優勢：無需另外的組件，缺點：須要會SQL及拼接HTML表格較麻煩；

三種方法我都有用過，若開發BS網站程序，建議採用第二種、第三種方法，若開發CS結構，建議採用第一種或第二種；

如下是我針對BS端寫的一個ExcelHelper通用類，可用於讀取或生成數據，比較方便，技術原理是上述的第三種方法，代碼以下，可能存在缺陷，高手見諒：

namespace ASOTS.Models
{
    public abstract class ExcelHelper
    {
        /// <summary>
        /// 獲取EXCEL中指定sheet內容
        /// </summary>
        /// <returns></returns>
        public static DataTable GetTableFromExcel(string filePath, string fileExt, string tableName, int colsCount)
        {
            string connstr = null;
            if (fileExt == ".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'";
            }

            using (OleDbConnection excelConn = new OleDbConnection(connstr))
            {
                excelConn.Open();

                //獲取EXCEL架構信息
                DataTable schemaTable = excelConn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, new Object[] { null, null, null, "TABLE" });

                //判斷指定sheet名是否存在
                DataView schemaView = new DataView(schemaTable);
                schemaView.RowFilter = "TABLE_NAME='" + tableName + "$'";
                schemaTable = schemaView.ToTable();

                if (schemaTable != null && schemaTable.Rows.Count > 0)
                {
                    DataTable schemaTable_Cols = excelConn.GetOleDbSchemaTable(OleDbSchemaGuid.Columns, new object[] { null, null, tableName + "$", null });
                    schemaView = new DataView(schemaTable_Cols);
                    schemaView.RowFilter = "ORDINAL_POSITION<=" + colsCount.ToString();
                    schemaView.Sort = "ORDINAL_POSITION asc";
                    schemaTable_Cols = schemaView.ToTable();
                    string selectCols = "";
                    for (int i = 0; i < schemaTable_Cols.Rows.Count; i++)
                    {
                        selectCols += "," + schemaTable_Cols.Rows[i]["COLUMN_NAME"].ToString();
                    }

                    selectCols = selectCols.Substring(1);

                    //查詢sheet中的數據
                    string strSql = "select " + selectCols + " from [" + tableName + "$]";
                    OleDbDataAdapter da = new OleDbDataAdapter(strSql, excelConn);
                    DataSet ds = new DataSet();
                    da.Fill(ds, tableName);
                    excelConn.Close();
                    return ds.Tables[tableName];
                }
                else
                {
                    excelConn.Close();
                    return null;
                }
            }

        }

        /// <summary>
        /// 將數據模型集合對象生成HTML表格字符串
        /// </summary>
        /// <param name="data"></param>
        /// <param name="tableAttributes"></param>
        /// <param name="headers"></param>
        /// <returns></returns>
        public static string SetDataToHtmlTable(IEnumerable data, string tableAttributes, params KeyValuePair<string, string>[] headers)
        {
            StringBuilder htmlTableBuilder = new StringBuilder();
            htmlTableBuilder.AppendFormat("<table {0}>", tableAttributes);

            if (data.GetEnumerator().Current == null)
            {
                throw new Exception("沒有獲取到任何數據！");
            }

            Type t = data.GetEnumerator().Current.GetType();

            string[] cellIndexs = new string[headers.Count()];

            htmlTableBuilder.Append("<tr>");
            for (int i = 0; i < headers.Count(); i++)
            {
                cellIndexs[i] = headers[i].Key;
                htmlTableBuilder.AppendFormat("<th>{0}</th>", headers[i].Value);
            }
            htmlTableBuilder.Append("</tr>");

            foreach (var item in data)
            {
                htmlTableBuilder.Append("<tr>");
                for (int i = 0; i < cellIndexs.Length; i++)
                {
                    object pValue = t.GetProperty(cellIndexs[i]).GetValue(item, null);
                    htmlTableBuilder.AppendFormat("<td>{0}</td>", pValue);
                }
                htmlTableBuilder.Append("</tr>");
            }

            htmlTableBuilder.Append("</table>");

            return htmlTableBuilder.ToString();
        }



        /// <summary>
        /// 將DataTable對象生成HTML表格字符串
        /// </summary>
        /// <param name="data"></param>
        /// <param name="tableAttributes"></param>
        /// <param name="headers"></param>
        /// <returns></returns>
        public static string SetDataToHtmlTable(DataTable dataTable, string tableAttributes, params KeyValuePair<string, string>[] headers)
        {
            StringBuilder htmlTableBuilder = new StringBuilder();
            htmlTableBuilder.AppendFormat("<table {0}>", tableAttributes);

            htmlTableBuilder.Append("<tr>");
            for (int i = 0; i < headers.Count(); i++)
            {
                htmlTableBuilder.AppendFormat("<th>{0}</th>", headers[i].Value);
            }
            htmlTableBuilder.Append("</tr>");

            foreach (DataRow row in dataTable.Rows)
            {
                htmlTableBuilder.Append("<tr>");
                for (int i = 0; i < headers.Count(); i++)
                {
                    htmlTableBuilder.AppendFormat("<td>{0}</td>", row[headers[i].Key]);
                }
                htmlTableBuilder.Append("</tr>");
            }

            htmlTableBuilder.Append("</table>");

            return htmlTableBuilder.ToString();
        }

    }

    public class KeyValueList<TKey, TValue> : List<KeyValuePair<TKey, TValue>>
    {
        public void Add(TKey key, TValue value)
        {
            base.Add(new KeyValuePair<TKey, TValue>(key, value));
        }
    }
}

調用方法以下：

//讀數據
DataTable resultTable = ExcelHelper.GetTableFromExcel(saveFilePath, fileExt, "data", 10);

//生成表格（如下是MVC調用，WEBFORM同理）
KeyValueList<string, string> headers = new KeyValueList<string, string>() { 
                        {"year","年 份"},
                        {"month","月 份"},
                        {"stage1count","一 階"},
                        {"stage2count","二 階"},
                        {"stage3count","三 階"},
                        {"stage4count","四 階"},
                        {"yearincount","一年內進廠"},
                        {"stagetotalcount","基盤客戶總數"},
                        {"stage1rate","一階佔比"},
                        {"stage2rate","二階佔比"},
                        {"stage3rate","三階佔比"},
                        {"stage4rate","四階佔比"}
                };

                string tableAttributes = "border='1' cellspacing='3' cellpadding='3'";

                string htmlTable=ExcelHelper.SetDataToHtmlTable(model, tableAttributes, headers.ToArray());
                byte[] b = System.Text.Encoding.UTF8.GetBytes(htmlTable);

                return File(b, "application/vnd.ms-excel", string.Format("StageSummary_{0}_{1}_{2}.xls",orgcode,startym,endym));

其中：KeyValueList是我建立的一個集合類，主要用於生成表頭，以及表頭與數據列對應，之因此寫成類，是由於若直接使用：List<KeyValuePair<TKey, TValue>>，則沒法直接使用集合初始化器，就必需得一個一個的添加對象，有些繁瑣，增長了ADD方法後，就能夠直接用：new KeyValueList<string, string>() {{"",""},...}很方便，有人可能說爲何不用SortedDictionary等現有排序類，緣由是SortedDictionary是基於Key排序，而此處是採用ADD的前後順序來固定順序的。

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