如何防止在Gridview创建的控件在回发后消失

本文主要讲述如何实现在标题头上放一个按钮上去，按下去选择一整个列的功能。用三种方法演示效果。

 

方法一（较简单）：

使用模板列

 

HTML code <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns=False Width="230px">
    <Columns>
        <asp:TemplateField>
            <HeaderTemplate>
                <asp:Button ID="Button1" runat="server" Text="全选" OnClick="Button1_Click" />
            </HeaderTemplate>
            <ItemTemplate>
                <%#Eval("id") %>
            </ItemTemplate>
        </asp:TemplateField>
        <asp:BoundField DataField="title" />
    </Columns>
</asp:GridView> C# code protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        DataTable dt = new DataTable();
        dt.Columns.Add("title");
        dt.Columns.Add("id");
        dt.Rows.Add("sdafsa","1");
        dt.Rows.Add("sdafsa","2");
        dt.Rows.Add("sdafsa","3");
        dt.Rows.Add("sdafsa","4");
        GridView1.DataSource = dt;
        GridView1.DataBind();
    }
}
protected void Button1_Click(object sender, EventArgs e)
{
    Button bt = (Button)sender;
    if (bt.Text == "全选")
        for (int i = 0; i < GridView1.Rows.Count; i++)
        {
            GridView1.Rows[i].Cells[0].Style.Add("background-color", "red");
            bt.Text = "取消";
        }
    else
        for (int i = 0; i < GridView1.Rows.Count; i++)
        {
            GridView1.Rows[i].Cells[0].Style.Add("background-color", "white");
            bt.Text = "全选";
        }
}

 

 

方法二（中等难度）：在Page_Load中的if (!IsPostBack){}外边动态添加控件

 

 

HTML code <asp:GridView ID="GridView1" runat="server"  Width="230px" OnRowDataBound="GridView1_OnRowDataBound">
</asp:GridView>

 

C# code protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        DataTable dt = new DataTable();
        dt.Columns.Add("title");
        dt.Columns.Add("id");
        dt.Rows.Add("sdafsa", "1");
        dt.Rows.Add("sdafsa", "2");
        dt.Rows.Add("sdafsa", "3");
        dt.Rows.Add("sdafsa", "4");
        GridView1.DataSource = dt;
        GridView1.DataBind();
    }
    Button bt = new Button();
    //bt.ID = "bt1";
    bt.Text = "测试";
    bt.CommandArgument = "1";
    bt.Click += new EventHandler(bt_Click);
    GridView1.HeaderRow.Cells[1].Controls.Add(bt);
}
protected void GridView1_OnRowDataBound(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.Header)
    {
        //Button bt = new Button();
        //bt.ID = "bt1";
        //bt.Text = "测试";
        //bt.CommandArgument = "1";
        //bt.Click+=new EventHandler(bt_Click);
        //e.Row.Cells[1].Controls.Add(bt);
    }
}
protected void bt_Click(object sender, EventArgs e)
{
    Button bt = (Button)sender;
    if (bt.CommandArgument == "1")
        for (int i = 0; i < GridView1.Rows.Count; i++)
        {
            GridView1.Rows[i].Cells[0].Style.Add("background-color", "red");
            bt.CommandArgument = "0";
        }
    else
        for (int i = 0; i < GridView1.Rows.Count; i++)
        {
            GridView1.Rows[i].Cells[0].Style.Add("background-color", "white");
            bt.CommandArgument = "1";
        }
}

 

 

 

第三种（有点难度）：

使用viewstate保存序列化后的控件，在创建时再反序列化

 

HTML code

<asp:GridView ID="GridView1" runat="server"  Width="230px"  OnLoad="GridView1_Load">
</asp:GridView>

 

C# code  

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            DataTable dt = new DataTable();
            dt.Columns.Add("title");
            dt.Columns.Add("id");
            dt.Rows.Add("sdafsa", "1");
            dt.Rows.Add("sdafsa", "2");
            dt.Rows.Add("sdafsa", "3");
            dt.Rows.Add("sdafsa", "4");
            GridView1.DataSource = dt;
            GridView1.DataBind();
        }
    }
    protected void GridView1_Load(object sender, EventArgs e)
    {

            oButton bt = new oButton();
            if (ViewState["but"] == null)
            {
                bt.ID = "bt1";
                bt.Text = "测试";
                bt.arg = "1";          
                ViewState["but"] = bt;
            }
            else
                bt = ViewState["but"] as oButton;
            bt.Click += new EventHandler(bt_Click);
            GridView1.HeaderRow.Cells[1].Controls.Add(bt);

    }
    protected void bt_Click(object sender, EventArgs e)
    {
        oButton bt = (oButton)sender;
        if (bt.arg == "1")
            for (int i = 0; i < GridView1.Rows.Count; i++)
            {
                GridView1.Rows[i].Cells[0].Style.Add("background-color", "red");
                bt.arg = "0";
            }
        else
            for (int i = 0; i < GridView1.Rows.Count; i++)
            {
                GridView1.Rows[i].Cells[0].Style.Add("background-color", "white");
                bt.arg = "1";
            }
        ViewState["but"] = bt;
    }
这是重点，重写button类，并继承ISerializable接口，以实现button的可序列化：
[Serializable]
class oButton : Button, System.Runtime.Serialization.ISerializable
{
    public string arg;
    public oButton() { }
    protected oButton(System.Runtime.Serialization.SerializationInfo info,
        System.Runtime.Serialization.StreamingContext context)
    {
        this.ID = info.GetString("id");
        this.Text = info.GetString("txt");
        this.arg = info.GetString("arg");
    }

    public void GetObjectData(System.Runtime.Serialization.SerializationInfo info,
        System.Runtime.Serialization.StreamingContext context)
    {
        info.AddValue("id", this.ID);
        info.AddValue("txt", this.Text);
        info.AddValue("arg", this.arg);
    }

}