我們主要研究RenderControl,Render,RenderChildren的執行順序.
三者的含義從他們的命名可以很清楚的看出.
RenderControl繪制控件
Render繪制
RenderChildren繪制子控件
看下面的代碼
public class UserComponent : Control
{
public UserComponent()
{
}
public override void RenderControl(HtmlTextWriter writer)
{
writer.Write(@"<script language=\'javascript\'>alert(\'RenderControl\');</script>");
//base.RenderControl(writer);
}
protected override void Render(HtmlTextWriter writer)
{
writer.Write(@"<script language=\'javascript\'>alert(\'Render\');</script>");
//base.Render(writer);
}
protected override void RenderChildren(HtmlTextWriter writer)
{
writer.Write(@"<script language=\'javascript\'>alert(\'RenderChildren\');</script>");
//base.RenderChildren(writer);
}
}
運作程式:隻彈出對話框 RenderControl
說明:最先被調用的是 RenderControl 繪制控件
将base.RenderControl(writer);的注釋去掉
public override void RenderControl(HtmlTextWriter writer)
{
writer.Write(@"<script language=\'javascript\'>alert(\'RenderControl\');</script>");
base.RenderControl(writer);
}
運作程式:彈出對話框 RenderControl 然後彈出對話框 Render
說明:控件通過 RenderControl 調用了 Redner
将base.Render(writer);的注釋去掉
protected override void Render(HtmlTextWriter writer)
{
writer.Write(@"<script language=\'javascript\'>alert(\'Render\');</script>");
base.Render(writer);
}
運作程式:彈出對話框 RenderControl 然後彈出對話框 Render 然後彈出對話框 RenderChildren
說明:控件通過 RenderControl 調用了 Redner 調用 RenderChildren
現在來看下面的代碼,應該有些感覺了吧...
using System;
using System.Web.UI;
namespace WebComponent
{
public class UserComponent : Control
{
public UserComponent()
{
}
public override void RenderControl(HtmlTextWriter writer)
{
//writer.Write(@"<script language=\'javascript\'>alert(\'RenderControl\');</script>");
//base.RenderControl(writer);
if (this.Visible)
{
Render(writer);
}
}
protected override void Render(HtmlTextWriter writer)
{
//writer.Write(@"<script language=\'javascript\'>alert(\'Render\');</script>");
//base.Render(writer);
RenderChildren(writer);
}
protected override void RenderChildren(HtmlTextWriter writer)
{
//writer.Write(@"<script language=\'javascript\'>alert(\'RenderChildren\');</script>");
//base.RenderChildren(writer);
foreach (Control c in this.Controls)
{
c.RenderControl(writer);
}
}
}
}
