ListView控件(一)--增，删，改，查

ASP.NET3.5中包含了新的数据绑定控件--ListView，这是一个类似与repeater与gridview结合的控件，可以实现添加，删除功能，同时还可以像repeater一样灵活的控制页面的布局。该控件包含了很多新的模板，比如GroupTemplate等新增的模板，可以方便的分组显示数据。详细的大家可以去查MSDN文档。

我一直认为学习数据绑定控件从最简单的增删改查开始，可以对该控件有较深刻的理解，这样可以举一反三，在进行综合运用。今天这篇文章还是从最基本的数据操作开始，对ListView有个感性的认识。

页面源码：

  <asp:ListView ID="ListView1" runat="server" OnSelectedIndexChanging="ListView1_SelectedIndexChanging"
            OnItemCommand="ListView1_ItemCommand" 
            OnItemEditing="ListView1_ItemEditing" OnItemCanceling="ListView1_ItemCanceling"
            OnItemDataBound="ListView1_ItemDataBound" OnPagePropertiesChanging="ListView1_PagePropertiesChanging"
            OnItemInserting="ListView1_ItemInserting" OnItemUpdating="ListView1_ItemUpdating"
            OnSorting="ListView1_Sorting" EnableViewState="true" 
            InsertItemPosition="LastItem" onitemdeleting="ListView1_ItemDeleting">
            <LayoutTemplate>
                <asp:PlaceHolder ID="itemPlaceholder" runat="server"></asp:PlaceHolder>
                <p>
                    <asp:DataPager ID="MyPage" runat="server" PageSize="6">
                        <Fields>
                            <asp:NumericPagerField ButtonCount="10" PreviousPageText="<-- " NextPageText="-->" />
                            <%...--   <asp:NextPreviousPagerField ButtonType="Button" ShowFirstPageButton="true" ShowLastPageButton="true"
                            ShowNextPageButton="true" ShowPreviousPageButton="true" />--%>
                        </Fields>
                    </asp:DataPager>
                </p>
            </LayoutTemplate>
            <ItemTemplate>
                <i>
                    <%...#Eval("SupplierID")%></i>
                <p>
                    <b>
                        <%...#Eval("CompanyName")%></b></p>
                <p>
                    <%...#Eval("ContactName")%></p>
                <p>
                    <%...#Eval("Address")%></p>
                <p>
                    <%...#Eval("City")%></p>
                <asp:Button ID="btnEdit" runat="server" Text="Edit" CommandName="Edit" />
                <asp:Button ID="btnDelete" runat="server" Text="Delete" CommandName="Delete" />
                <%...--  <asp:LinkButton ID="lbtnSort" runat="server" Text="Sort" CommandName="Sort" CommandArgument="CompanyName" ></asp:LinkButton>--%>
            </ItemTemplate>
            <EditItemTemplate>
                <asp:TextBox ID="txtMy" runat="server" Text='<%#bind("SupplierID") %>'></asp:TextBox>
                <asp:TextBox ID="TextBox1" runat="server" Text='<%#bind("CompanyName") %>'></asp:TextBox>
                <asp:TextBox ID="TextBox2" runat="server" Text='<%#bind("ContactName") %>'></asp:TextBox>
                <asp:TextBox ID="TextBox3" runat="server" Text='<%#bind("Address") %>'></asp:TextBox>
                <asp:TextBox ID="TextBox4" runat="server" Text='<%#bind("City") %>'></asp:TextBox>
                <asp:Button ID="btnUpdate" runat="server" Text="Update" CommandName="Update" />
                <asp:Button ID="btnCancle" runat="server" Text="Cancle" CommandName="Cancel" />
            </EditItemTemplate>
            <InsertItemTemplate>
                <asp:TextBox ID="txtMy" runat="server" Text='<%#bind("SupplierID") %>'></asp:TextBox>
                <asp:TextBox ID="TextBox1" runat="server" Text='<%#bind("CompanyName") %>'></asp:TextBox>
                <asp:TextBox ID="TextBox2" runat="server" Text='<%#bind("ContactName") %>'></asp:TextBox>
                <asp:TextBox ID="TextBox3" runat="server" Text='<%#bind("Address") %>'></asp:TextBox>
                <asp:TextBox ID="TextBox4" runat="server" Text='<%#bind("City") %>'></asp:TextBox>
                <asp:Button ID="btnUpdate" runat="server" Text="Insert" CommandName="Insert" />
                <asp:Button ID="btnCancle" runat="server" Text="Cancle" CommandName="Cancel" />
            </InsertItemTemplate>
            <ItemSeparatorTemplate>
                <div style="height: 0px; border-top: dashed 1px #ff0000">
                </div>
            </ItemSeparatorTemplate>
            
        </asp:ListView>

这部分代码中有个重要的部分就是通过<LayoutTemplate>模板来设置控件的样式，布局，这也是新增的模板。在VS.NET2008的正式版本中，要正常运行页面必须在该模板中加入一个名为itemPlaceholder的PlaceHolder控件。要不会出现如下异常：

An item placeholder must be specified on ListView 'ListView1'. Specify an item placeholder by setting a control's ID property to "itemPlaceholder".

<ItemTemplate>模板用来绑定显示到页面上的数据， <EditItemTemplate>用来显示处于编辑状态的时候显示的数据，其他的可以以此类推。

与ListView还搭配的一起使用了新增的DataPager控件，这个主要是用于ListView控件的分页，是新增的分页空也，可以方便，高效的进行分页。

后台代码：

    string ConStr = ConfigurationManager.ConnectionStrings["NorthwindConnectionString"].ConnectionString;
    protected void Page_Load(object sender, EventArgs e)
    ...{
        if (!IsPostBack)
        ...{
            ViewState["SupplierID"] = "SupplierID";
            ViewState["Direction"] = "DESC";
            BindListView();
        }

    }

    private void BindListView()
    ...{
        string QueryCon = "SELECT SupplierID,CompanyName,ContactName,Address,City FROM Suppliers";
        SqlConnection NorthWindCon = new SqlConnection(ConStr);
        SqlDataAdapter NorthWindDa = new SqlDataAdapter(QueryCon, ConStr);
        DataSet Ds = new DataSet();
        NorthWindDa.Fill(Ds, "Suppliers");
        ListView1.DataKeyNames = new string[] ...{ "SupplierID" };
        DataView Dv = Ds.Tables["Suppliers"].DefaultView;
        //排序表达式
        string SortExpress = (string)ViewState["SupplierID"] + " " + (string)ViewState["Direction"];
        Dv.Sort = SortExpress;
        //绑定数据源
        //ListView1.DataSource = Ds.Tables["Suppliers"];
        ListView1.DataSource = Dv;
        ListView1.DataBind();

    }


    protected void ListView1_ItemEditing(object sender, ListViewEditEventArgs e)
    ...{
        ListView1.EditIndex = e.NewEditIndex;
        BindListView();
    }


    protected void ListView1_ItemDataBound(object sender, ListViewItemEventArgs e)
    ...{
        if (e.Item.ItemType == ListViewItemType.DataItem)
        ...{
            ((Button)e.Item.FindControl("btnDelete")).Attributes["onclick"] = "if(!confirm('你真的要删除这条记录么?'))return   false;";
        }
        
    }

    protected void ListView1_ItemCanceling(object sender, ListViewCancelEventArgs e)
    ...{
        //取消编辑
        if (e.CancelMode == ListViewCancelMode.CancelingEdit)
        ...{
            //e.Cancel = true;
            ListView1.EditIndex = -1;
            BindListView();
            ShowMessage("取消编辑");
        }
        else if (e.CancelMode == ListViewCancelMode.CancelingInsert)
        ...{
            //BindListView();
            return;
        }


    }


    protected void ListView1_ItemInserting(object sender, ListViewInsertEventArgs e)
    ...{
        ((TextBox)ListView1.InsertItem.FindControl("txtMy")).ReadOnly = true;
        string CompanyName = Server.HtmlEncode(((TextBox)ListView1.InsertItem.FindControl("TextBox1")).Text.ToString());
        string ContactName = Server.HtmlEncode(((TextBox)ListView1.InsertItem.FindControl("TextBox2")).Text.ToString());
        string Address = Server.HtmlEncode(((TextBox)ListView1.InsertItem.FindControl("TextBox3")).Text.ToString());
        string City = Server.HtmlEncode(((TextBox)ListView1.InsertItem.FindControl("TextBox4")).Text.ToString());

        string InsertQuery = "INSERT INTO Suppliers (CompanyName,ContactName,Address,City) VALUES ('" + CompanyName + "','" + ContactName + "','" + Address + "','" + City + "')";
        SqlConnection InsertCon = new SqlConnection(ConStr);
        SqlCommand InsertCmd = new SqlCommand(InsertQuery, InsertCon);
        try
        ...{
            InsertCon.Open();
            InsertCmd.ExecuteNonQuery();
            BindListView();
            //将插入行显示到最后
            ListView1.InsertItemPosition = InsertItemPosition.LastItem;

        }
        catch
        ...{
            ShowMessage("插入新数据出错，请重新输入");
        }
        finally
        ...{
            InsertCon.Dispose();
            InsertCmd.Dispose();
        }
    }

    protected void ListView1_ItemUpdating(object sender, ListViewUpdateEventArgs e)
    ...{
        string KeyId = ListView1.DataKeys[e.ItemIndex].Value.ToString();
        //找到listview改行的数据集合
        string CompanyName = Server.HtmlEncode(((TextBox)ListView1.Items[e.ItemIndex].FindControl("TextBox1")).Text.ToString());
        string ContactName = Server.HtmlEncode(((TextBox)ListView1.Items[e.ItemIndex].FindControl("TextBox2")).Text.ToString());
        string Address = Server.HtmlEncode(((TextBox)ListView1.Items[e.ItemIndex].FindControl("TextBox3")).Text.ToString());
        string City = Server.HtmlEncode(((TextBox)ListView1.Items[e.ItemIndex].FindControl("TextBox4")).Text.ToString());
        string UpdateStr = "UPDATE Suppliers SET CompanyName='" + CompanyName + "',ContactName='" + ContactName + "'," +
                            "Address='" + Address + "',City='" + City + " 'WHERE SupplierID='" + KeyId + "' ";
        SqlConnection UpdateCon = new SqlConnection(ConStr);
        SqlCommand UpdateCmd = new SqlCommand(UpdateStr, UpdateCon);
        try
        ...{
            UpdateCon.Open();
            UpdateCmd.ExecuteNonQuery();
            ListView1.EditIndex = -1;
            BindListView();
        }
        catch
        ...{
            ShowMessage("更新出错，请重新编辑");
        }
        finally
        ...{
            UpdateCon.Dispose();
            UpdateCmd.Dispose();
        }
    }


    protected void ListView1_Sorting(object sender, ListViewSortEventArgs e)
    ...{
        if (ViewState["SupplierID"].ToString() == e.SortExpression)
        ...{
            if (ViewState["Direction"].ToString() == "DESC")
            ...{
                ViewState["Direction"] = "ASC";
            }
            else
            ...{
                ViewState["Direction"] = "DESC";
            }
        }
        else
        ...{
            ViewState["SupplierID"] = e.SortExpression;
        }
        BindListView();
    }


    private void ShowMessage(string Message)
    ...{
        Literal TxtMsg = new Literal();
        TxtMsg.Text = "<script>alert('" + Message + "')</script>";
        Page.Controls.Add(TxtMsg);
    }

    protected void ListView1_ItemDeleting(object sender, ListViewDeleteEventArgs e)
    ...{
        string KeyID = ListView1.DataKeys[e.ItemIndex].Value.ToString();
        string DeleteStr = "DELETE FROM Suppliers WHERE SupplierID='" + KeyID + "'";
        SqlConnection DeleteCon = new SqlConnection(ConStr);
        SqlCommand DeleteCmd = new SqlCommand(DeleteStr, DeleteCon);
        try
        ...{
            DeleteCon.Open();
            DeleteCmd.ExecuteNonQuery();
            BindListView();
            ShowMessage("删除成功");
        }
        catch 
        ...{
            ShowMessage("删除出错，请检查数据是否有关联");
        }
        finally
        ...{
            DeleteCon.Dispose();
            DeleteCmd.Dispose();
        }
    }

以前的edit_cancel事件在ListView控件中为item_cancel，在该事件中可以判断是取消编辑还是取消插入新的数据。大家可以看代码。本篇文章主要是对ListView控件一些基本的事件的运用。下一篇会继续深入的学习该控件。