集合属性相信大家都很熟悉也很常用,如DropDownList,ListBox等控件
<asp:DropDownList ID="DropDownList1" runat="server"> <asp:ListItem>测试1</asp:ListItem> <asp:ListItem>测试2</asp:ListItem> <asp:ListItem>测试3</asp:ListItem> </asp:DropDownList>1.实现集合属性效果
经过前面几篇的学习,相信这一篇看起来已经相对简单了.我们要做的就是,先定义一个复杂属性,然后用迭代语句获取数组数据即可.
如果看过前面几篇就看看下面代码吧,相信看起来很简单,我们模仿一个DropDownList,为其属性添加背景属性,代码如下
先定义一个集合属性,如下
public class DropItem { private string text; private string value; private Color backColor; [ Category("Behavior"), DefaultValue(""), Description("项文本"), NotifyParentProperty(true), ] public String Text { get { return text; } set { text = value; } } [ Category("Behavior"), DefaultValue(""), Description("项值"), NotifyParentProperty(true), ] public String Value { get { return value; } set { this.value = value; } } [ Category("Behavior"), DefaultValue(""), Description("背景颜色"), NotifyParentProperty(true), ] public Color BackColor { get { return backColor; } set { backColor = value; } } }然后自定义一个控件,输出集合属性,如下代码
[ParseChildren(true, "DropItemList")] public class DropColor:WebControl { private ArrayList dropItemList; [ Category("Behavior"), Description("项集合"), DesignerSerializationVisibility( DesignerSerializationVisibility.Content), PersistenceMode(PersistenceMode.InnerDefaultProperty), ] //定义集合属性 public ArrayList DropItemList { get { if (dropItemList == null) { dropItemList = new ArrayList(); } return dropItemList; } } //重写标签 protected override HtmlTextWriterTag TagKey { get { return HtmlTextWriterTag.Select; } } protected override void RenderContents(HtmlTextWriter writer) { //输出集合属性 foreach (DropItem item in dropItemList) { DropItem dr = item as DropItem; if (dropItemList != null && dropItemList.Count > 0) { //颜色转换 WebColorConverter wcc = new WebColorConverter(); writer.AddAttribute(HtmlTextWriterAttribute.Value, dr.Value.ToString()); writer.AddStyleAttribute(HtmlTextWriterStyle.BackgroundColor, wcc.ConvertToString(dr.BackColor)); writer.RenderBeginTag(HtmlTextWriterTag.Option); writer.Write(dr.Text.ToString()); writer.RenderEndTag(); } } base.RenderContents(writer); } }上面代码注意颜色类型之间的转换,以下为HTML代码
<custom:DropColor ID="DropColor1" runat="server" ForeColor="White"> <custom:DropItem BackColor="Yellow" Text="黄色" Value="yellow" /> <custom:DropItem BackColor="Red" Text="红色" Value="red" /> <custom:DropItem BackColor="Blue" Text="蓝色" Value="blue" /> <custom:DropItem BackColor="Green" Text="绿色" Value="green" /> <custom:DropItem BackColor="Black" Text="黑色" Value="Black" /> </custom:DropColor>输出以后的效果如下图
效果还不错吧,而且挺实用的.
