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关于ASP.NET的一个小问题

0
[已关闭问题]

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        string ConStr = @"Server=(local)\sqlexpress;DataBase=db_07;Uid=sa;Pwd=a963.";
        string cmdtxt = "SELECT * FROM tb_07";
        SqlConnection Con = new SqlConnection(ConStr);
        SqlDataAdapter da = new SqlDataAdapter(cmdtxt, Con);
        DataSet ds = new DataSet();
        da.Fill(ds);
        this.GridView1.DataSource = ds;
        this.GridView1.DataBind();

        if (ViewState["Count"] != null)
        {
            for (int i = 0; i < Convert.ToInt16(ViewState["Count"]); i++)
            {
                //AddTextBox();
                Response.Write("<script>allert('ViewState!=null 当!当!当!当!');</script>");
            }
        }
        else
        {
            this.btnData.Enabled = false;
            Response.Write("<script>allert('ViewState==null 哈哈!');</script>");
        }
    }
    //向页面中添加文本框
    public void AddTextBox()
    {
        //行
        TableRow tr = new TableRow();
        //单元格1
        TableCell tc1 = new TableCell();
        //TextBox
        TextBox txt = new TextBox();

        txt.ID = "tb" + Table1.Rows.Count;
        txt.Font.Size = FontUnit.Point(9);

        //单元格2
        TableCell tc2 = new TableCell();

        //Label
        Label lab = new Label();
        lab.ID = "lab" + Table1.Rows.Count;
        lab.Width = 50;
        lab.Text = "数据" + (Table1.Rows.Count + 1);

        tc2.Controls.Add(lab);
        tc1.Controls.Add(txt);

        tr.Cells.Add(tc2);
        tr.Cells.Add(tc1);
        Table1.Rows.Add(tr);
    }

    protected void Button1_Click(object sender, EventArgs e)
    {
        Response.Write("<script>allert('添加输入框');</script>");
        //动态添加控件
        AddTextBox();
        ViewState["Count"] = Convert.ToInt16(ViewState["Count"]) + 1;
        this.btnData.Enabled = true;
    }

    protected void btnData_Click(object sender, EventArgs e)
    {
        Response.Write("<script>allert('开始插入');</script>");
        string ConStr = @"Server=(local)\sqlexpress;DataBase=db_07;Uid=sa;Pwd=a963.";
        SqlConnection Con = new SqlConnection(ConStr);
        Con.Open();
        SqlCommand Com;
        string cmdtxt = String.Empty;
        //将文本框中的内容循环插入到数据库中
        for (int i = 0; i < Table1.Rows.Count; i++)
        {
            cmdtxt = "INSERT INTO tb_07(name) VALUES('" + ((TextBox)Table1.Rows[i].FindControl("tb" + i)).Text + "')";
            Com = new SqlCommand(cmdtxt, Con);
            Com.ExecuteNonQuery();
        }
        Response.Write("<script>allert('数据插入成功!');location='Default.aspx'</script>");
    }
}


在上面,为什么在Page_Load里面,要再次执行 AddTextBox();呢,

如果不执行,发现添加不了数据。

 点击添加数据按钮后,不是直接读取输入框中的数据就行了,为什么还要再一次生成输入框?

我是新手,自学来着,请指点一下

rails.net的主页 rails.net | 初学一级 | 园豆:200
提问于:2009-02-26 23:25
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其他回答(6)
0

因为动态生成的控件会在下一次Load的时候消失,因此必须在Load的时候把他加回去,其实是个很复杂的问题……

Gray Zhang | 园豆:17610 (专家六级) | 2009-02-26 23:51
0

嗯,主要是页面模型的问题。很多人把asp.net当winform了,其实asp.net是无状态的。另外label和textbox貌似都可以用viewstate保存状态。

zeus2 | 园豆:92 (初学一级) | 2009-02-27 08:01
0

支持楼上的

子夜星辰 | 园豆:1613 (小虾三级) | 2009-02-27 08:43
0

让页面不回发一下,!ispostback

艾新 | 园豆:202 (菜鸟二级) | 2009-02-27 09:12
0

点击按钮之后,asp.net实际上会先执行PageLoad方法,然后才会进入click事件响应,如果PageLoad方法中没有填加控件,点击按钮后控件就会丢失。

如果你需要保存值,应该在LoadPage方法里将其写入数据库,或是用一个全局变量(在类内方法外声明)来保存。

维博.WILBUR | 园豆:235 (菜鸟二级) | 2009-02-27 09:28
0

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    if(!ispostback)

{
        string ConStr = @"Server=(local)\sqlexpress;DataBase=db_07;Uid=sa;Pwd=a963.";
        string cmdtxt = "SELECT * FROM tb_07";
        SqlConnection Con = new SqlConnection(ConStr);
        SqlDataAdapter da = new SqlDataAdapter(cmdtxt, Con);
        DataSet ds = new DataSet();
        da.Fill(ds);
        this.GridView1.DataSource = ds;
        this.GridView1.DataBind();

        if (ViewState["Count"] != null)
        {
            for (int i = 0; i < Convert.ToInt16(ViewState["Count"]); i++)
            {
                //AddTextBox();
                Response.Write("<script>allert('ViewState!=null 当!当!当!当!');</script>");
            }
        }
        else
        {
            this.btnData.Enabled = false;
            Response.Write("<script>allert('ViewState==null 哈哈!');</script>");
        }

}
    }
    //向页面中添加文本框
    public void AddTextBox()
    {
        //行
        TableRow tr = new TableRow();
        //单元格1
        TableCell tc1 = new TableCell();
        //TextBox
        TextBox txt = new TextBox();

        txt.ID = "tb" + Table1.Rows.Count;
        txt.Font.Size = FontUnit.Point(9);

        //单元格2
        TableCell tc2 = new TableCell();

        //Label
        Label lab = new Label();
        lab.ID = "lab" + Table1.Rows.Count;
        lab.Width = 50;
        lab.Text = "数据" + (Table1.Rows.Count + 1);

        tc2.Controls.Add(lab);
        tc1.Controls.Add(txt);

        tr.Cells.Add(tc2);
        tr.Cells.Add(tc1);
        Table1.Rows.Add(tr);
    }

    protected void Button1_Click(object sender, EventArgs e)
    {
        Response.Write("<script>allert('添加输入框');</script>");
        //动态添加控件
        AddTextBox();
        ViewState["Count"] = Convert.ToInt16(ViewState["Count"]) + 1;
        this.btnData.Enabled = true;
    }

    protected void btnData_Click(object sender, EventArgs e)
    {
        Response.Write("<script>allert('开始插入');</script>");
        string ConStr = @"Server=(local)\sqlexpress;DataBase=db_07;Uid=sa;Pwd=a963.";
        SqlConnection Con = new SqlConnection(ConStr);
        Con.Open();
        SqlCommand Com;
        string cmdtxt = String.Empty;
        //将文本框中的内容循环插入到数据库中
        for (int i = 0; i < Table1.Rows.Count; i++)
        {
            cmdtxt = "INSERT INTO tb_07(name) VALUES('" + ((TextBox)Table1.Rows[i].FindControl("tb" + i)).Text + "')";
            Com = new SqlCommand(cmdtxt, Con);
            Com.ExecuteNonQuery();
        }
        Response.Write("<script>allert('数据插入成功!');location='Default.aspx'</script>");
    }
}

加上ispostback

梁颢 | 园豆:215 (菜鸟二级) | 2009-02-27 13:16
0

ASp.NET得运行机制 是先Page_Load

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    if(!ispostback)

    {

     AddTextBox();

    }

 }

  public void AddTextBox()
    {

  。。。。。。。。

  }

}

李苏 | 园豆:240 (菜鸟二级) | 2009-02-28 14:22
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