asp.net使用控件datagrid实现表头单元格合并

合并的要点:

1.datagid的单元格合并原理是table中tr,td的布局实现;

2.合并的时机实在其datagridcreate事件中实现;

3.认识一个对象TableCellCollection,它是由TableCell组成的集合,TableCell可以看成一个标题.

实现下面的效果;

前台只有一个空DataGrid,后台源码如下:

private DataTable dt = null;
        protected void Page_Load(object sender, EventArgs e)
        {
            //数据源
            dt = new DataTable();
            dt.Columns.Add("姓名");
            dt.Columns.Add("年龄");
            dt.Columns.Add("住址");
            dt.Columns.Add("公司");
            dt.Columns.Add("邮件");
            dt.Columns.Add("电话");

            //绑定数据源
            mydg.DataSource = dt;
            mydg.DataBind();

        }

        protected void mydg_ItemCreated(object sender, DataGridItemEventArgs e)
        {
            if (e.Item.ItemType == ListItemType.Header)
            {
                List<CellRule> ils = new List<CellRule>();


                TableCellCollection tcc = e.Item.Cells;
                tcc.Add(new TableCell());
                tcc[0].Text = dt.Columns[0].ColumnName;
                tcc[0].Attributes.Add("rowspan", "2");
                tcc.Add(new TableCell());
                tcc[1].Text = dt.Columns[1].ColumnName;
                tcc[1].Attributes.Add("rowspan", "2");
                tcc.Add(new TableCell());
                tcc[2].Attributes.Add("colspan", "4");
                tcc[2].Text = "详细信息</th></tr><tr>";
                tcc[2].HorizontalAlign = HorizontalAlign.Center;


                tcc.Add(new TableCell());
                tcc[3].Text = dt.Columns[2].ColumnName;
                tcc.Add(new TableCell());
                tcc[4].Text = dt.Columns[3].ColumnName;
                tcc.Add(new TableCell());
                tcc[5].Text = dt.Columns[4].ColumnName;
                tcc.Add(new TableCell());
                tcc[6].Text = dt.Columns[5].ColumnName;



                //ils.Add(new CellRule(2, 4, "详细信息"));
                //OganizeTcc(e.Item.Cells, ils, dt);
            }
        }

再将合并表头单元格封装成通用的方法:

优化后的代码如下:

private DataTable dt = null;
        protected void Page_Load(object sender, EventArgs e)
        {
            //数据源
            dt = new DataTable();
            dt.Columns.Add("姓名");
            dt.Columns.Add("年龄");
            dt.Columns.Add("住址");
            dt.Columns.Add("公司");
            dt.Columns.Add("邮件");
            dt.Columns.Add("电话");

            //绑定数据源
            mydg.DataSource = dt;
            mydg.DataBind();

        }

        protected void mydg_ItemCreated(object sender, DataGridItemEventArgs e)
        {
            if (e.Item.ItemType == ListItemType.Header)
            {
                List<CellRule> ils = new List<CellRule>();


                //TableCellCollection tcc = e.Item.Cells;
                //tcc.Add(new TableCell());
                //tcc[0].Text = dt.Columns[0].ColumnName;
                //tcc[0].Attributes.Add("rowspan", "2");
                //tcc.Add(new TableCell());
                //tcc[1].Text = dt.Columns[1].ColumnName;
                //tcc[1].Attributes.Add("rowspan", "2");
                //tcc.Add(new TableCell());
                //tcc[2].Attributes.Add("colspan", "4");
                //tcc[2].Text = "详细信息</th></tr><tr>";
                //tcc[2].HorizontalAlign = HorizontalAlign.Center;


                //tcc.Add(new TableCell());
                //tcc[3].Text = dt.Columns[2].ColumnName;
                //tcc.Add(new TableCell());
                //tcc[4].Text = dt.Columns[3].ColumnName;
                //tcc.Add(new TableCell());
                //tcc[5].Text = dt.Columns[4].ColumnName;
                //tcc.Add(new TableCell());
                //tcc[6].Text = dt.Columns[5].ColumnName;



                ils.Add(new CellRule(2, 4, "详细信息"));
                OganizeTcc(e.Item.Cells, ils, dt);
            }
        }

        private void OganizeTcc(TableCellCollection tcc, List<CellRule> ils, DataTable dt)
        {
            tcc.Clear();
            ils = ils.OrderBy(p => p.iStart).ToList();
            List<string> secHeaders = new List<string>();
            //第一行
            for (int i = 0, j = 0; j < dt.Columns.Count;)
            {
                if (i >= ils.Count || ils[i].iStart != j)
                {
                    tcc.Add(new TableCell());
                    tcc[tcc.Count - 1].Text = dt.Columns[j].ColumnName;
                    tcc[tcc.Count - 1].Attributes.Add("rowspan", "2");
                    j++;
                    if (j == dt.Columns.Count)
                        tcc[tcc.Count - 1].Text = tcc[tcc.Count - 1].Text + "</th></tr><tr>";
                }
                else 
                {
                    for (int iSec = 0; iSec < ils[i].iCount; iSec++)
                    {
                        secHeaders.Add(dt.Columns[j + iSec].ColumnName);
                    }
                    tcc.Add(new TableCell());      
                    tcc[tcc.Count-1].Text = ils[i].strHeaderText;
                    tcc[tcc.Count - 1].Attributes.Add("colspan", ils[i].iCount.ToString());
                    tcc[tcc.Count - 1].HorizontalAlign = HorizontalAlign.Center;
                    j = j + ils[i].iCount;
                    i++;
                    if(j == dt.Columns.Count)
                        tcc[tcc.Count-1].Text = tcc[tcc.Count-1].Text+"</th></tr><tr>";
                }
                
            }
            //第二行
            foreach (string str in secHeaders)
            {
                tcc.Add(new TableCell());
                tcc[tcc.Count - 1].Text = str;
            }
        }

设定合并规则的实体类:

public class CellRule
    {
        public int iStart { get; set; }
        public int iCount { get; set; }
        public string strHeaderText { get; set; }
        public CellRule(int iStart, int iCount, string strHeaderText)
        {
            this.iStart = iStart;
            this.iCount = iCount;
            this.strHeaderText = strHeaderText;
        }
    }

现在只有一阶转二阶的方法,如果在搞成N阶通用的方法,我是暂时想不到了.就这样.