代码改变世界

可以动态加载UserControl的ViewPanel控件

2006-12-10 13:12  Cat Chen  阅读(4398)  评论(35编辑  收藏  举报
using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

namespace CatChen.Cocollab.Web.UI.Controls
{
    
public class ViewPanel : System.Web.UI.Control, System.Web.UI.INamingContainer
    
{
        
private string _virtualPath;
        
private Control _view;

        
public string VirtualPath
        
{
            
get return this._virtualPath; }
            
set
            
{
                
string oldValue = this._virtualPath;
                
this._virtualPath = value;
                
if (this.Page != null && value != oldValue)
                
{
                    
this.ChildControlsCreated = false;
                    
this.EnsureChildControls();
                }

            }

        }

        
public Control View
        
{
            
get return this._view; }
        }


        
protected override void OnInit(EventArgs e)
        
{
            
base.OnInit(e);
            
if (!string.IsNullOrEmpty(this.VirtualPath))
            
{
                
this.EnsureChildControls();
            }

        }


        
protected override void LoadViewState(object savedState)
        
{
            Pair pair 
= savedState as Pair;
            
if (pair != null)
            
{
                
base.LoadViewState(pair.First);
                
this.VirtualPath = pair.Second as string;
            }

        }


        
protected override void CreateChildControls()
        
{
            
this.Controls.Clear();

            
if (string.IsNullOrEmpty(this.VirtualPath))
            
{
                
return;
            }


            
if (this.Page == null)
            
{
                
throw new Exception("ViewPanel.Page is null.");
            }


            
this._view = this.Page.LoadControl(this.VirtualPath);
            
if (this._view == null)
            
{
                
throw new Exception("ViewVirtualPath cannot be loaded.");
            }


            
this._view.ID = "ucView";
            
this.ClearChildState();
            
this.Controls.Add(this._view);
        }


        
protected override object SaveViewState()
        
{
            
return new Pair(base.SaveViewState(), this.VirtualPath);
        }

    }

}