Excel多表头导出(.net)

分享一下以前做的.net版本的Excel多表头导出，其中使用了第三方插件NPOI （java推荐使用POI）。

demo下载

以下是算法部分：

  public static string ExportTable(ArrayList data, ArrayList columns)
    {

        ArrayList columnsBottom = getColumnsBottom(columns);

        ArrayList columnsTable = getColumnsTable(columns);

        StringBuilder sb = new StringBuilder();
        //data = ds.DataSetName + "\n";


        //data += tb.TableName + "\n";
        sb.AppendLine("<meta http-equiv=\"Content-Type\" content=\"text/html; charset=gb2312\">");
        sb.AppendLine("<table cellspacing=\"0\" cellpadding=\"5\" rules=\"all\" border=\"1\">");
        //写出列名

        for (int i = 0; i < columnsTable.Count; i++)
        {
            ArrayList columnsRow = (ArrayList)columnsTable[i];
            sb.AppendLine("<tr style=\"font-weight: bold; white-space: nowrap;\">");
            foreach (Hashtable column in columnsRow)
            {
                sb.AppendLine("<td colspan=" + column["colspan"] + " rowspan=" + column["rowspan"] + ">" + column["header"] + "</td>");
            }
            sb.AppendLine("</tr>");
        }
        //写出数据

        int count = 0;
        foreach (Hashtable row in data)
        {
            sb.Append("<tr>");
            foreach (Hashtable column in columnsBottom)
            {
                Object value;
                if (column["field"] != null)
                {
                    value = row[column["field"]];
                }
                else
                {
                    value = "";
                }
                if (Convert.ToString(column["type"]) == "indexcolumn") value = count + 1;
                sb.AppendLine("<td >" + value + "</td>");
            }
            sb.AppendLine("</tr>");
            count++;
        }
        sb.AppendLine("</table>");


        return sb.ToString();
    }

    public static ArrayList getColumnsBottom(ArrayList columns)
    {
        ArrayList columnsBottom = new ArrayList();

        for (int i = 0; i < columns.Count; i++)
        {
            Hashtable column = (Hashtable)columns[i];

            if (column["columns"] != null)
            {
                ArrayList childColumns = (ArrayList)column["columns"];
                columnsBottom.AddRange(getColumnsBottom(childColumns));
            }
            else
            {
                columnsBottom.Add(column);
            }

        }
        return columnsBottom;
    }

    public static ArrayList getColumnsTable(ArrayList columns)
    {
        ArrayList table = new ArrayList();

        getColumnsRows(columns, 0, table);

        createTableSpan(table);

        return table;

    }

    public static void getColumnsRows(ArrayList columns, int level, ArrayList table)
    {
        ArrayList row = null;
        if (table.Count > level)
        {
            row = (ArrayList)table[level];
        }
        else
        {
            row = new ArrayList();
            table.Add(row);
        }

        for (int i = 0; i < columns.Count; i++)
        {

            Hashtable column = (Hashtable)columns[i];
            ArrayList childColumns = (ArrayList)column["columns"];

            row.Add(column);

            if (childColumns != null)
            {

                getColumnsRows(childColumns, level + 1, table);
            }

        }
    }

    public static void createTableSpan(ArrayList table)
    {
        for (int i = 0; i < table.Count; i++)
        {
            ArrayList row = (ArrayList)table[i];  //row
            for (int l = 0; l < row.Count; l++)
            {
                Hashtable cell = (Hashtable)row[l];   //column

                int colSpan = getColSpan(cell);
                cell["colspan"] = colSpan;

                if (colSpan > 1)
                {
                    cell["rowspan"] = 1;
                }
                else
                {
                    cell["rowspan"] = table.Count - i;
                }

            }
        }
    }

    public static int getColSpan(Hashtable column)
    {
        int colSpan = 0;
        ArrayList childColumns = (ArrayList)column["columns"];
        if (childColumns != null)
        {
            for (int i = 0; i < childColumns.Count; i++)
            {
                Hashtable child = (Hashtable)childColumns[i];
                colSpan += getColSpan(child);
            }
        }
        else
        {
            colSpan = 1;
        }
        return colSpan;
    }