asp.net中使用自定义控件的方式实现一个分页控件的代码
在web开发中，常常需要显示一些数据，而为了方便排版及浏览，我们只需要显示所有记录中的一部分。一般情况下，我们采用分页来实现这个需求。实现分页的方法多种多样，在本文中，我们采用了一个分页空间来记录记录总数、当前页、总页数及页面大小等。为了有一个直观上的印象，先展示该控件运行后的效果，效果如下图所示：
二、实现方案
为了实现该效果图，在asp.net中，可以使用Custom Controls and User Controls两种方式，User Controls的实现方式及其简单，而且使用起来和平时使用Controls的方式差别极大，所以我们采用Custom Controls实现。
参考资料：Professional ASP.NET 2.0 Server Control and Component Development
三、分页控件的实现
1）、新建一个ASP.NET Server Control项目,
2）、在该项目中添加一个ASP.NET Server Control的Item，并设置其Name为PageOn,
3）、修改该类继承于CompositeControl类，并修改其Attribute为如下所示：
[DefaultProperty("PageSize")]
[ToolboxData("<{0}:PageOn runat=server Width=100%></{0}:PageOn>")]
public class PageOn : CompositeControl
注：自定义控件必须继承自Control或者其子类。
4）、 定义需要被组合的控件
Label lblMessage;
LinkButton btnFirst;
LinkButton btnPrev;
LinkButton btnNext;
LinkButton btnLast;
TextBox txtGoPage;
Button btnGo;
5）、定义分页控件需要用到的Proptery
分页控件主要包括页面大小、当前页、总记录数及总页数等属性，并需要保存在ViewState中，详细代码如下所示：
public int RowCount
{
get
{
if (ViewState["m_rowCount"] == null || int.Parse(ViewState["m_rowCount"].ToString()) < 0)
{
ViewState["m_rowCount"] = 0;
}
return int.Parse(ViewState["m_rowCount"].ToString());
}
set
{
if (value < 0)
{
ViewState["m_rowCount"] = 0;
}
else
{
ViewState["m_rowCount"] = value;
}
this.RecreateChildControls();
}
}
public int CurPage
{
get
{
if (ViewState["m_curPage"] ==null || int.Parse(ViewState["m_curPage"].ToString()) < 1)
{
ViewState["m_curPage"] = 1;
}
return int.Parse(ViewState["m_curPage"].ToString());
}
set
{
if (value < 1)
{
ViewState["m_curPage"] = 1;
}
else if (value > PageCount)
{
ViewState["m_curPage"] = PageCount;
}
else
{
ViewState["m_curPage"] = value;
}
}
}
public int PageCount
{
get
{
return RowCount / PageSize + 1;
}
}
public int PageSize
{
get
{
if (ViewState["m_pageSize"] ==null || int.Parse(ViewState["m_pageSize"].ToString()) < 1)
{
ViewState["m_pageSize"] = 15;
}
return int.Parse(ViewState["m_pageSize"].ToString());
}
set
{
if (value > 0)
{
ViewState["m_pageSize"] = value;
this.RecreateChildControls();
}
}
}
6）、生成自定义控件的子空间
生成自定义空间的子空间需要override基类Control中的CreateChildControls()方法，详细代码如下所示：
protected override void CreateChildControls()
{
Controls.Clear();
lblMessage = new Label();
lblMessage.Text = "当前第" + CurPage + "页 共" + PageCount + "页 共" + RowCount + "条记录";
lblMessage.ID = "lblMessage";
Controls.Add(lblMessage);
btnFirst = new LinkButton();
btnFirst.Text = "首页";
btnFirst.CommandName = "first";
btnFirst.ID = "btnFirst";
if (CurPage <= 1)
{
btnFirst.Enabled = false;
}
Controls.Add(btnFirst);
btnPrev = new LinkButton();
btnPrev.Text = "上一页";
btnPrev.CommandName = "prev";
btnPrev.ID = "btnPrev";
if (CurPage <= 1)
{
btnPrev.Enabled = false;
}
Controls.Add(btnPrev);
btnNext = new LinkButton();
btnNext.Text = "下一页";
btnNext.CommandName = "next";
btnNext.ID = "btnNext";
if (CurPage >= PageCount)
{
btnNext.Enabled = false;
}
Controls.Add(btnNext);
btnLast = new LinkButton();
btnLast.Text = "末页";
btnLast.CommandName = "last";
btnLast.ID = "btnLast";
if (CurPage >= PageCount)
{
btnLast.Enabled = false;
}
Controls.Add(btnLast);
txtGoPage = new TextBox();
txtGoPage.TabIndex = 1;
txtGoPage.ID = "txtGoPage";
txtGoPage.Attributes.Add("onkeyup", @"this.value=this.value.replace(/\D/g,'')");
txtGoPage.Attributes.Add("onafterpaste", @"this.value=this.value.replace(/\D/g,'')");
Controls.Add(txtGoPage);
btnGo = new Button();
btnGo.TabIndex = 2;
btnGo.CommandName = "go";
btnGo.Text = "GO";
btnGo.ID="btnGO";
Controls.Add(btnGo);
Debug.WriteLine("ffffffffffffffffffffffffffffffffffffffffffffffffff");
base.CreateChildControls();
}
7）、定义自定义控件的布局
第6步完成后，所有定义的控件都会顺序显示到页面上了，但是这样的效果不友好，如果对于多行的空间更是如此，所有我们需要定义控件的布局，自定义控件的布局需要重写RenderContents()方法及TagKey属性，此示例中的代码如下所示：
protected override void RenderContents(HtmlTextWriter output)
{
output.RenderBeginTag(HtmlTextWriterTag.Tr);
output.AddStyleAttribute("text-align", "left");
output.RenderBeginTag(HtmlTextWriterTag.Td);
output.Write(" ");
lblMessage.RenderControl(output);
output.RenderEndTag();
output.AddStyleAttribute("text-align", "right");
output.RenderBeginTag(HtmlTextWriterTag.Td);
btnFirst.RenderControl(output);
output.Write(" ");
btnPrev.RenderControl(output);
output.Write(" ");
btnNext.RenderControl(output);
output.Write(" ");
btnLast.RenderControl(output);
output.Write("到");
output.AddStyleAttribute(HtmlTextWriterStyle.Width, "30px");
txtGoPage.RenderControl(output);
output.Write("页");
btnGo.RenderControl(output);
output.Write(" ");
output.RenderEndTag();
output.RenderEndTag();
}
protected override HtmlTextWriterTag TagKey
{
get
{
return HtmlTextWriterTag.Table;
}
}
上面的代码中，我们使用Table来布局，也可以使用其它的布局方式，比如DIV+CSS。
8）、捕捉并处理控件的事件
到此以后，这些代码已经可以生成文章开头图所显示的效果，但是什么事情也做不了，不能响应该控件上的事件，所有还需要继续实现该控件上的事件代码，实现这些事件采用冒泡所有子控件的事件来实现。
首先，定义一个委托：
public delegate void PageOnEventHandler(object sender, EventArgs args);
其次，定义基于该委托的事件：
public event PageOnEventHandler RecPageChanged;
最后，重写冒泡事件，并根据参数特征，捕获需要处理的事件，使其调用需要的方法。
protected override bool OnBubbleEvent(object source, EventArgs args)
{
bool handled = false;
CommandEventArgs cea = args as CommandEventArgs;
if(cea == null)
{
return handled;
}
switch (cea.CommandName)
{
case "first":
handled = true;
CurPage = 1;
break;
case "prev":
handled = true;
if (CurPage > 1)
{
CurPage--;
}
else
{
CurPage = 1;
}
break;
case "next":
handled = true;
if (CurPage < PageCount)
{
CurPage ++ ;
}
else
{
CurPage = PageCount;
}
break;
case "last":
handled = true;
CurPage = PageCount;
break;
case "go":
string strGo = txtGoPage.Text.Trim();
int iGo;
if (!string.IsNullOrEmpty(strGo) && int.TryParse(strGo, out iGo))
{
handled = true;
CurPage = iGo;
}
break;
}
if (handled)
{
if (this.RecPageChanged != null)
{
RecPageChanged(this, args);
this.RecreateChildControls();
}
return handled;
}
else
{
return base.OnBubbleEvent(source, args);
}
}
到此就完成了分页控件的开发。
注:可以定制该控件的样式,或者使用属性暴露子控件的属性来控制样式等.
四、使用分页控件
完成自定义控件的开发后，在Toolbox中Choose Items或者直接在需要使用该自定义控件的项目中引用该项目或者DLL，即可在Toolbox中显示自定义控件了。然后用拖拽的方式即可把分页控件放到需要的地方，就像使用button控件一样简单。
然后再该页面的后台代码的OnLoad事件中，注册需要被调用的方法到该控件的RecPageChanged事件中，如下所示：
PageOn1.RecPageChanged += new CustomControl.PageOnEventHandler(PageOn1_RecPageChanged);
最后，只需要在方法PageOn1_RecPageChanged中编写自己的代码即可。
void PageOn1_RecPageChanged(object sender, EventArgs args)
{
//To do something
}
控件的详细代码如下:
namespace CustomControl
{
public delegate void PageOnEventHandler(object sender, EventArgs args);
[DefaultProperty("PageSize")]
[ToolboxData("<{0}:PageOn runat=server Width=100%></{0}:PageOn>")]
public class PageOn :CompositeControl
{
#region
Label lblMessage;
LinkButton btnFirst;
LinkButton btnPrev;
LinkButton btnNext;
LinkButton btnLast;
TextBox txtGoPage;
Button btnGo;
#endregion
protected override void CreateChildControls()
{
Controls.Clear();
lblMessage = new Label();
lblMessage.Text = "当前第" + CurPage + "页 共" + PageCount + "页 共" + RowCount + "条记录";
lblMessage.ID = "lblMessage";
Controls.Add(lblMessage);
btnFirst = new LinkButton();
btnFirst.Text = "首页";
btnFirst.CommandName = "first";
btnFirst.ID = "btnFirst";
if (CurPage <= 1)
{
btnFirst.Enabled = false;
}
Controls.Add(btnFirst);
btnPrev = new LinkButton();
btnPrev.Text = "上一页";
btnPrev.CommandName = "prev";
btnPrev.ID = "btnPrev";
if (CurPage <= 1)
{
btnPrev.Enabled = false;
}
Controls.Add(btnPrev);
btnNext = new LinkButton();
btnNext.Text = "下一页";
btnNext.CommandName = "next";
btnNext.ID = "btnNext";
if (CurPage >= PageCount)
{
btnNext.Enabled = false;
}
Controls.Add(btnNext);
btnLast = new LinkButton();
btnLast.Text = "末页";
btnLast.CommandName = "last";
btnLast.ID = "btnLast";
if (CurPage >= PageCount)
{
btnLast.Enabled = false;
}
Controls.Add(btnLast);
txtGoPage = new TextBox();
txtGoPage.TabIndex = 1;
txtGoPage.ID = "txtGoPage";
txtGoPage.Attributes.Add("onkeyup", @"this.value=this.value.replace(/\D/g,'')");
txtGoPage.Attributes.Add("onafterpaste", @"this.value=this.value.replace(/\D/g,'')");
Controls.Add(txtGoPage);
btnGo = new Button();
btnGo.TabIndex = 2;
btnGo.CommandName = "go";
btnGo.Text = "GO";
btnGo.ID="btnGO";
Controls.Add(btnGo);
Debug.WriteLine("ffffffffffffffffffffffffffffffffffffffffffffffffff");
base.CreateChildControls();
}
public int RowCount
{
get
{
if (ViewState["m_rowCount"] == null || int.Parse(ViewState["m_rowCount"].ToString()) < 0)
{
ViewState["m_rowCount"] = 0;
}
return int.Parse(ViewState["m_rowCount"].ToString());
}
set
{
if (value < 0)
{
ViewState["m_rowCount"] = 0;
}
else
{
ViewState["m_rowCount"] = value;
}
this.RecreateChildControls();
}
}
public int CurPage
{
get
{
if (ViewState["m_curPage"] ==null || int.Parse(ViewState["m_curPage"].ToString()) < 1)
{
ViewState["m_curPage"] = 1;
}
return int.Parse(ViewState["m_curPage"].ToString());
}
set
{
if (value < 1)
{
ViewState["m_curPage"] = 1;
}
else if (value > PageCount)
{
ViewState["m_curPage"] = PageCount;
}
else
{
ViewState["m_curPage"] = value;
}
}
}
public int PageCount
{
get
{
return RowCount / PageSize + 1;
}
}
public int PageSize
{
get
{
if (ViewState["m_pageSize"] ==null || int.Parse(ViewState["m_pageSize"].ToString()) < 1)
{
ViewState["m_pageSize"] = 15;
}
return int.Parse(ViewState["m_pageSize"].ToString());
}
set
{
if (value > 0)
{
ViewState["m_pageSize"] = value;
this.RecreateChildControls();
}
}
}
protected override void RenderContents(HtmlTextWriter output)
{
output.RenderBeginTag(HtmlTextWriterTag.Tr);
output.AddStyleAttribute("text-align", "left");
output.RenderBeginTag(HtmlTextWriterTag.Td);
output.Write(" ");
lblMessage.RenderControl(output);
output.RenderEndTag();
output.AddStyleAttribute("text-align", "right");
output.RenderBeginTag(HtmlTextWriterTag.Td);
btnFirst.RenderControl(output);
output.Write(" ");
btnPrev.RenderControl(output);
output.Write(" ");
btnNext.RenderControl(output);
output.Write(" ");
btnLast.RenderControl(output);
output.Write("到");
output.AddStyleAttribute(HtmlTextWriterStyle.Width, "30px");
txtGoPage.RenderControl(output);
output.Write("页");
btnGo.RenderControl(output);
output.Write(" ");
output.RenderEndTag();
output.RenderEndTag();
}
protected override HtmlTextWriterTag TagKey
{
get
{
return HtmlTextWriterTag.Table;
}
}
public event PageOnEventHandler RecPageChanged;
protected override bool OnBubbleEvent(object source, EventArgs args)
{
bool handled = false;
CommandEventArgs cea = args as CommandEventArgs;
if(cea == null)
{
return handled;
}
switch (cea.CommandName)
{
case "first":
handled = true;
CurPage = 1;
break;
case "prev":
handled = true;
if (CurPage > 1)
{
CurPage--;
}
else
{
CurPage = 1;
}
break;
case "next":
handled = true;
if (CurPage < PageCount)
{
CurPage ++ ;
}
else
{
CurPage = PageCount;
}
break;
case "last":
handled = true;
CurPage = PageCount;
break;
case "go":
string strGo = txtGoPage.Text.Trim();
int iGo;
if (!string.IsNullOrEmpty(strGo) && int.TryParse(strGo, out iGo))
{
handled = true;
CurPage = iGo;
}
break;
}
if (handled)
{
if (this.RecPageChanged != null)
{
RecPageChanged(this, args);
this.RecreateChildControls();
}
return handled;
}
else
{
return base.OnBubbleEvent(source, args);
}
}
}
}
OK，完成