Question

C# 一个很怪的问题有关于CheckBoxList...,请教高手

protected void Page_Load(object sender, EventArgs e)
{
string conStr = "Server=LocalHost;Integrated Security=SSPI;DataBase=Fruits";
SqlConnection conn = new SqlConnection(conStr);
string selStr = "select * from fruitsClass";
SqlDataAdapter da = new SqlDataAdapter(selStr, conn);
DataSet ds = new DataSet();
da.Fill(ds);
this.CheckBoxList1.DataSource = ds;
this.CheckBoxList1.DataValueField = "id";
this.CheckBoxList1.DataTextField = "Class";
this.CheckBoxList1.DataBind();
}
protected void Button1_Click(object sender, EventArgs e)
{
string fruit = "";
for (int i = 0; i < this.CheckBoxList1.Items.Count - 1; i++)
{
if (this.CheckBoxList1.Items[i].Selected)
{
fruit = fruit + this.CheckBoxList1.Items[i].Text;
}

}
this.Label1.Text = fruit;
}
我运行后，选择某些复选框，然后单击按钮，但是标签中什么也没有，求解~~~

Answer 1

你把整个执行过程 运行一般 就一目了然了。。。。。
你这样写 永远取不到值。！
if(!Page.IsPostback)
{
string conStr = "Server=LocalHost;Integrated Security=SSPI;DataBase=Fruits";
SqlConnection conn = new SqlConnection(conStr);
string selStr = "select * from fruitsClass";
SqlDataAdapter da = new SqlDataAdapter(selStr, conn);
DataSet ds = new DataSet();
da.Fill(ds);
this.CheckBoxList1.DataSource = ds;
this.CheckBoxList1.DataValueField = "id";
this.CheckBoxList1.DataTextField = "Class";
this.CheckBoxList1.DataBind();
}

追问

谢谢啊，我会给你分的，但是为什么一定要加上if(!Page.IsPostback){}

Answer 2

这个问题我貌似也碰到过，想了蛮久，应该是页面生成周期的原因吧，你定义一个Page_Init方法，把Page_Load里面的代码都放到Page_Init里面就可以了。
protected void Page_Init(object sender,EventArgs e)
{
string conStr = "Server=LocalHost;Integrated Security=SSPI;DataBase=Fruits";
SqlConnection conn = new SqlConnection(conStr);
string selStr = "select * from fruitsClass";
SqlDataAdapter da = new SqlDataAdapter(selStr, conn);
DataSet ds = new DataSet();
da.Fill(ds);
this.CheckBoxList1.DataSource = ds;
this.CheckBoxList1.DataValueField = "id";
this.CheckBoxList1.DataTextField = "Class";
this.CheckBoxList1.DataBind();
}
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Button1_Click(object sender, EventArgs e)
{
string fruit = "";
for (int i = 0; i < this.CheckBoxList1.Items.Count - 1; i++)
{
if (this.CheckBoxList1.Items[i].Selected)
{
fruit = fruit + this.CheckBoxList1.Items[i].Text;
}

}
this.Label1.Text = fruit;
}
有问题再问我吧