DataListItemCollection 類別

參考

定義

命名空間:: System.Web.UI.WebControls

組件:: System.Web.dll

重要

部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。

表示 DataListItem 控制項中 DataList 物件的集合。此類別無法獲得繼承。

public ref class DataListItemCollection sealed : System::Collections::ICollection

public sealed class DataListItemCollection : System.Collections.ICollection

type DataListItemCollection = class
    interface ICollection
    interface IEnumerable

Public NotInheritable Class DataListItemCollection
Implements ICollection

繼承: Object
DataListItemCollection

實作: ICollection IEnumerable

範例

下列範例會以控制項的形式 DataView 建立資料來源，並將它系結至 DataList 標記中宣告的控制項。然後，它會在頁面上顯示基礎 DataListItemCollection 物件的內容。

<%@ Import Namespace = "System.Data"  %>
<%@ Page language="c#" AutoEventWireup="true"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">    
// The following example creates a DataSource as a DataView.
// The DataView is bound to a DataList that is displayed using an
// ItemTemplate. When the page is first loaded, the program uses the 
// CopyTo method to copy the entire data source to an Array and then 
// displays that data.

ICollection CreateDataSource()
{
    DataTable myDataTable = new DataTable();
    DataRow myDataRow;

    myDataTable.Columns.Add(new DataColumn("EmployeeName", typeof(string)));
    myDataTable.Columns.Add(new DataColumn("EmployeeID", typeof(long)));
    for (int i = 0; i < 3; i++)
    {
        myDataRow = myDataTable.NewRow();
        myDataRow[0] = "somename" + i.ToString();
        myDataRow[1] = (i+1000);
        myDataTable.Rows.Add(myDataRow);
    }
    DataView dataView = new DataView(myDataTable);
    return dataView;
}

// <Snippet2>
void Page_Load(Object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        // Bind the DataView to the DataSource.
        myDataList.DataSource = CreateDataSource();
        myDataList.DataBind();
        // Create a Array to hold the DataSource.
        System.Array myArray = Array.CreateInstance(typeof(DataListItem),
            myDataList.Items.Count);
        // Copy the DataSource to an Array.
        myDataList.Items.CopyTo(myArray,0);
        PrintValues(myArray);
    }
}

// Prints each element in the Array onto the label lblAllItems1.
public void PrintValues(Array myArr)
{
    DataListItem currentItem;
    System.Collections.IEnumerator myEnumerator = myArr.GetEnumerator();
    while (myEnumerator.MoveNext())
    {
        currentItem = (DataListItem)myEnumerator.Current;
        lblAllItems1.Text += "<br /><br />" + 
            ((Label)(currentItem.Controls[1])).Text;
    }
}

// Event handler method for show button.
void show_Click(Object sender,EventArgs e)
{
    // Get the underlying DataListItemCollection from the DataList object.
    DataListItemCollection myDataListItemCollection = myDataList.Items;
    // Display the read-only properties.
    Response.Write("<b>The Total number of items are " + 
        myDataListItemCollection.Count + "</b>");
    Response.Write("<br /><b>The ReadOnly property of the " + 
        "DataListItemCollection is always" + 
        myDataListItemCollection.IsReadOnly + "</b>");
    Response.Write("<br /><b>The IsSynchronized property of the " +
        "DataListItemCollection is always " +
        myDataListItemCollection.IsSynchronized + "</b>");
    myDataListItemCollection = null;
}
// </Snippet2>

// <Snippet5>
void allItems_Click(Object sender,EventArgs e)
{
    IEnumerator dataListEnumerator;
    DataListItem currentItem;
    lblAllItems.Text = "";
    // Get an enumerator to traverse the DataListItemCollection.
    dataListEnumerator = myDataList.Items.GetEnumerator();
    while(dataListEnumerator.MoveNext())
    {
        currentItem = (DataListItem)dataListEnumerator.Current;
        // Display the current DataListItem onto the label.
        lblAllItems.Text += ((Label)(currentItem.Controls[1])).Text + " ";
    }
}
// </Snippet5>

// <Snippet6>
void itemSelected(Object sender,EventArgs e)
{
    // Get the underlying DataListItemCollection from the DataList object.
    DataListItemCollection myDataListItemCollection = myDataList.Items;
    // Get the index of the selected radio button in the RadioButtonList.
    int index = Convert.ToInt16(listItemNo.SelectedItem.Value);
    // Get the DataListItem corresponding to index from DataList.
    // SyncRoot is used to make access to the DataListItemCollection 
    // in a thread-safe manner It returns the object that invoked it. 
    DataListItem currentItem = 
        ((DataListItemCollection)(myDataListItemCollection.SyncRoot))[index];
    // Display the selected DataListItem onto a label.
    lblDisplay.Text = "<b>DataListItem" + index + " is : "
        + ((Label)(currentItem.Controls[1])).Text;
    currentItem = null;
    myDataListItemCollection = null;
}
// </Snippet6>

</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
    <title>
        DataListItemCollection Example
    </title>
</head>
<body>
<form runat="server" id="Form1">
    <h3>
        DataListItemCollection Example
    </h3>
    <table>
        <tr>
            <td>
                <asp:datalist id="myDataList" runat="server" Font-Size="8pt" 
                    Font-Names="Verdana" BorderColor="black" CellSpacing="5"
                    CellPadding="10" GridLines="Horizontal">
                    <HeaderStyle BackColor="#aaaadd"></HeaderStyle>
                    <HeaderTemplate>
                        EmployeeName EmployeeID
                    </HeaderTemplate>
                    <ItemTemplate>
                        <asp:Label id="label1" runat="server"
                            Text='<%# DataBinder.Eval(Container.DataItem, "EmployeeName") %>'>
                        </asp:Label>
                            
                        <%# DataBinder.Eval(Container.DataItem, "EmployeeID")%>
                    </ItemTemplate>
                </asp:datalist>
            </td>
            <td>
                <asp:label id="lblAllItems1" 
                    Text="The following items <br /> are copied to the array: " 
                    Runat="server" ForeColor="blue" Font-Bold="true" 
                    AssociatedControlID="listItemNo">
                    The following items <br /> are copied to the array:
                </asp:label>
            </td>
            <td>
                    <b>Show Items:</b>
                <asp:RadioButtonList ID="listItemNo" 
                    OnSelectedIndexChanged="itemSelected" AutoPostBack="true" 
                    Runat="server">
                    <asp:ListItem Value="0" Text="0"></asp:ListItem>
                    <asp:ListItem Value="1" Text="1"></asp:ListItem>
                    <asp:ListItem Value="2" Text="2"></asp:ListItem>
                </asp:RadioButtonList>
            </td>
            <td>
                <asp:Label ID="lblDisplay" Runat="server" />
            </td>
        </tr>
    </table>
    <p>
        <asp:button id="show" onclick="show_Click" Runat="server" 
             Font-Bold="True" Text="DataList Information" />
        <asp:button id="allitems" onclick="allItems_Click" Runat="server" 
            Font-Bold="True" Text="Show All DataListItems" />
    </p>
    <p>
        <b>All DataList items will be shown here:</b>
        <asp:label id="lblAllItems" Runat="server" ForeColor="blue" />
    </p>
</form>
</body>
</html>

<%@ Import Namespace = "System.Data"  %>
<%@ Page language="VB" AutoEventWireup="true"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">    
' The following example creates a DataSource as a DataView.
' The DataView is bound to a DataList that is displayed using an
' ItemTemplate. When the page is first loaded, the program uses the 
' CopyTo method to copy the entire data source to an Array and then 
' displays that data.

Function CreateDataSource() As ICollection 
    Dim myDataTable As DataTable = New DataTable()
    Dim myDataRow As DataRow 
    Dim i As Integer

    myDataTable.Columns.Add(New DataColumn("EmployeeName", GetType(String)))
    myDataTable.Columns.Add(New DataColumn("EmployeeID", GetType(Integer)))
    For i = 0 To 2
        myDataRow = myDataTable.NewRow()
        myDataRow(0) = "somename" + i.ToString()
        myDataRow(1) = i + 1000
        myDataTable.Rows.Add(myDataRow)
    Next 
    CreateDataSource = new DataView(myDataTable)
End Function

' <Snippet2>
Sub Page_Load(sender As object, e As EventArgs)
    If (Not IsPostBack)
        ' Bind the DataView to the DataSource.
        myDataList.DataSource = CreateDataSource()
        myDataList.DataBind()
        ' Create a Array to hold the DataSource.
        Dim myArray As System.Array = Array.CreateInstance(GetType(DataListItem), _
            myDataList.Items.Count)
        ' Copy the DataSource to an Array.
        myDataList.Items.CopyTo(myArray, 0)
        PrintValues(myArray)
    End If
End sub

' Prints each element in the Array onto the label lblAllItems1.
Public Sub PrintValues(myArr As Array)
    Dim currentItem As DataListItem 
    Dim myEnumerator As System.Collections.IEnumerator = myArr.GetEnumerator()
    While (myEnumerator.MoveNext())
        currentItem = CType(myEnumerator.Current,DataListItem)
        lblAllItems1.Text = lblAllItems1.Text & "<br /><br />" & _
            CType(currentItem.Controls(1),Label).Text
    End While
End Sub

    ' Event handler method for show button.
Sub show_Click(sender as Object, e As EventArgs)
    ' Get the underlying DataListItemCollection from the DataList object.
    Dim myDataListItemCollection As DataListItemCollection = myDataList.Items
    ' Display the read-only properties.
    Response.Write("<b>The Total number of items are " & _
        myDataListItemCollection.Count & "</b>")
        Response.Write("<br /><b>The ReadOnly property of the " & _
            "DataListItemCollection is always " & _
            myDataListItemCollection.IsReadOnly & "</b>")
        Response.Write("<br /><b>The IsSynchronized property of the " & _
            "DataListItemCollection is always " _
            & myDataListItemCollection.IsSynchronized & "</b>")
    myDataListItemCollection = Nothing
End Sub
    ' </Snippet2>

' <Snippet5>
Sub AllItems_Click(sender As Object, e As EventArgs)
    Dim dataListEnumerator As IEnumerator
    Dim currentItem As DataListItem 
    lblAllItems.Text = ""
    ' Get an enumerator to traverse the DataListItemCollection.
    dataListEnumerator = myDataList.Items.GetEnumerator()
    while(dataListEnumerator.MoveNext())
        currentItem = CType(dataListEnumerator.Current,DataListItem)
        ' Display the current DataListItem onto the label.
        lblAllItems.Text = lblAllItems.Text & CType((currentItem.Controls(1)), _
        Label).Text & "  "
    End While
End Sub
' </Snippet5>

' <Snippet6>
Sub ItemSelected(sender As object, e As EventArgs)
    ' Get the underlying DataListItemCollection from the DataList object.
    Dim myDataListItemCollection As DataListItemCollection  = myDataList.Items
    ' Get the index of the selected radio button in the RadioButtonList.
    Dim index As Integer = Convert.ToInt16(listItemNo.SelectedItem.Value)
    ' Get the DataListItem corresponding to index from DataList.
    ' SyncRoot is used to make access to the DataListItemCollection 
    ' in a thread-safe manner It returns the object that invoked it. 
    Dim currentItem As DataListItem = _ 
        CType(myDataListItemCollection.SyncRoot,DataListItemCollection)(index)
    ' Display the selected DataListItem onto a label.
    lblDisplay.Text = "<b>DataListItem" & index & " is: " _
        & CType(currentItem.Controls(1),Label).Text
    currentItem = Nothing
    myDataListItemCollection = Nothing
End Sub
    ' </Snippet6>

</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
    <title>
        DataListItemCollection Example
    </title>
</head>
<body>
<form runat="server" id="Form1">
    <h3>
        DataListItemCollection Example
    </h3>
    <table>
        <tr>
            <td>
                <asp:datalist id="myDataList" runat="server" Font-Size="8pt" 
                    Font-Names="Verdana" BorderColor="black" CellSpacing="5"
                    CellPadding="10" GridLines="Horizontal">
                    <HeaderStyle BackColor="#aaaadd"></HeaderStyle>
                    <HeaderTemplate>
                        EmployeeName EmployeeID
                    </HeaderTemplate>
                    <ItemTemplate>
                        <asp:Label id="label1"  runat="server"
                            Text='<%# DataBinder.Eval(Container.DataItem, "EmployeeName") %>' />
                            
                        <%# DataBinder.Eval(Container.DataItem, "EmployeeID")%>
                    </ItemTemplate>
                </asp:datalist>
            </td>
            <td>
                <asp:label id="lblAllItems1" 
                    Text="The following items <br /> are copied to the array: " 
                    Runat="server" ForeColor="blue" Font-Bold="true" 
                    AssociatedControlID="listItemNo">
                    The following items <br /> are copied to the array:
                </asp:label>
            </td>
            <td>
                    <b>Show Items:</b>
                <asp:RadioButtonList ID="listItemNo" 
                    OnSelectedIndexChanged="itemSelected" AutoPostBack="true" 
                    Runat="server">
                    <asp:ListItem Value="0" Text="0"></asp:ListItem>
                    <asp:ListItem Value="1" Text="1"></asp:ListItem>
                    <asp:ListItem Value="2" Text="2"></asp:ListItem>
                </asp:RadioButtonList>
            </td>
            <td>
                <asp:Label ID="lblDisplay" Runat="server" />
            </td>
        </tr>
    </table>
    <p>
        <asp:button id="show" onclick="show_Click" Runat="server" 
            Font-Bold="True" Text="DataList Information" />
        <asp:button id="allitems" onclick="allItems_Click" Runat="server" 
            Font-Bold="True" Text="Show All DataListItems" />
    </p>
    <p>
        <b>All DataList items will be shown here:</b>
        <asp:label id="lblAllItems" Runat="server" ForeColor="blue" />
    </p>
</form>
</body>
</html>

備註

類別 DataListItemCollection 代表物件的集合 DataListItem ，接著代表控制項中的資料 DataList 項。若要以程式設計方式從 DataList 控制項擷取 DataListItem 物件，請使用下列其中一種方法：

使用索引子，使用陣列標記法從集合取得單 DataListItem 一物件。
CopyTo使用方法將集合 System.Array 的內容複寫到物件，然後可用來從集合取得專案。
GetEnumerator使用方法來建立 System.Collections.IEnumerator 介面，然後可用來從集合取得專案。

屬性 Count 會指定集合中的專案總數，通常用來判斷集合的上限。

建構函式

DataListItemCollection(ArrayList)

初始化 DataListItemCollection 類別的新執行個體。

屬性

Count	取得集合中 DataListItem 物件的數目。
IsReadOnly	取得值，指出是否可以修改 DataListItem 中的DataListItemCollection 物件。
IsSynchronized	取得值，指出 DataListItemCollection 的存取是否為同步處理 (安全執行緒)。
Item[Int32]	取得位於集合中指定索引的 DataListItem 物件。
SyncRoot	取得可用來同步存取 DataListItemCollection 集合的物件。

方法

CopyTo(Array, Int32)	從 DataListItemCollection 物件中指定的索引開始，將全部項目自這個 Array 集合複製到指定的 Array 物件。
Equals(Object)	判斷指定的物件是否等於目前的物件。 (繼承來源 Object)
GetEnumerator()	傳回 IEnumerator 介面，包含 DataListItem 中所有的 DataListItemCollection 物件。
GetHashCode()	做為預設雜湊函式。 (繼承來源 Object)
GetType()	取得目前執行個體的 Type。 (繼承來源 Object)
MemberwiseClone()	建立目前 Object 的淺層複製。 (繼承來源 Object)
ToString()	傳回代表目前物件的字串。 (繼承來源 Object)

擴充方法

Cast<TResult>(IEnumerable)	將 IEnumerable 的項目轉換成指定的型別。
OfType<TResult>(IEnumerable)	根據指定的型別來篩選 IEnumerable 的項目。
AsParallel(IEnumerable)	啟用查詢的平行化作業。
AsQueryable(IEnumerable)	將 IEnumerable 轉換成 IQueryable。

適用於

DataListItemCollection 類別

定義

範例

備註

建構函式

屬性

方法

擴充方法

適用於

另請參閱

其他資源