ASP.NET下Control的Deep Clone

最近在開發中有用到control的克隆,在網上搜索了許多文章,總結后代碼如下:

原由:

在做GridView的模板列生成方法時,想使用一個通用的方法,代碼如下:

 

   public class GridViewTemplate : ITemplate
        {
            Control _control;
            public GridViewTemplate(Control control)
            {
                _control = control;
            }

            public void InstantiateIn(Control container)
            {
                //Control descontrol = CloneControl(_control);
                //container.Controls.Add(descontrol);
　　　　　　　　　　container.Controls.Add(_control);
            }
}

 

這种做法的優點是生成的模板列內的控件由生成模板時生成在代入,不需要在iTemplate中寫死指定

那缺點很明顯,就是所有內部控件在內一列他的hashcode是一樣的,也就意味著整個gridview只有最后一行資料才能顯示正常的值,其它行的值都是空白.

解決方法:最后想到了在Itemplate中的InstantiateIn方法中用到contrl的克隆.才解決了這個問題.

修改后正確運行的代碼為

 

 public void InstantiateIn(Control container)
            {
                Control descontrol = CloneControl(_control);
                container.Controls.Add(descontrol);　　　　　　　　　
            }

 

 

下面是關於克隆的代碼:

1.Clone Method

private Control CloneControl(Control src_ctl)
            {
                try
                {
                    Type t = src_ctl.GetType();
                    Object obj = Activator.CreateInstance(t);
                    Control dst_ctl = (Control)obj;

                    PropertyDescriptorCollection src_pdc = TypeDescriptor.GetProperties(src_ctl);
                    PropertyDescriptorCollection dst_pdc = TypeDescriptor.GetProperties(dst_ctl);
                    
                    for (int i = 0; i < src_pdc.Count; i++)
                    {
                        if (src_pdc[i].Attributes.Contains(DesignerSerializationVisibilityAttribute.Content))
                        {
                            object collection_val = src_pdc[i].GetValue(src_ctl);
                            if ((collection_val is IList) == true)
                            {
                                foreach (object child in (IList)collection_val)
                                {
                                    Control new_child = CloneControl(child as Control);
                                    object dst_collection_val = dst_pdc[i].GetValue(dst_ctl);
                                    ((IList)dst_collection_val).Add(new_child);
                                }
                            }
                        }
                        else
                        {
                            dst_pdc[src_pdc[i].Name].SetValue(dst_ctl, src_pdc[i].GetValue(src_ctl));
                        }
                    }

                    EventDescriptorCollection events = TypeDescriptor.GetEvents(src_ctl);
                    for (int i = 0, cnt = events.Count; i < cnt; i++)
                    {
                        EventDatum ed = EventDatum.Create(src_ctl, events[i]);
                        if (ed != null)
                            ed.Wire(dst_ctl);
                    }                
                    return dst_ctl;
                }
                catch (Exception ex)
                {
                    throw ex;
                    return null;
                }
            }

 

 

2.Clone Event Class

 

   public class EventDatum
            {
                #region Fields
                private EventDescriptor _eventDesc;
                private Delegate _event;
                #endregion

                #region Static

                private static BindingFlags All
                {
                    get
                    {
                        return
                            BindingFlags.Public | BindingFlags.NonPublic |
                            BindingFlags.Instance | BindingFlags.IgnoreCase |
                            BindingFlags.Static;
                    }
                }

                private static MethodInfo GetEventsMethod(Type objType)
                {
                    MethodInfo mi = objType.GetMethod("get_Events", All);
                    if ((mi == null) & (objType.BaseType != null))
                        mi = GetEventsMethod(objType.BaseType);
                    return mi;
                }

                private static EventHandlerList GetEvents(object obj)
                {
                    MethodInfo mi = GetEventsMethod(obj.GetType());
                    if (mi == null) return null;
                    return (EventHandlerList)mi.Invoke(obj, new object[] { });
                }

                private static System.Reflection.FieldInfo GetEventIDField(Type objType, string eventName)
                {
                    System.Reflection.FieldInfo fi = objType.GetField("Event" + eventName, All);
                    if ((fi == null) & (objType.BaseType != null))
                        fi = GetEventIDField(objType.BaseType, eventName);
                    return fi;
                }

                private static object GetEventID(object obj, string eventName)
                {
                    System.Reflection.FieldInfo fi = GetEventIDField(obj.GetType(), eventName);
                    if (fi == null)
                        return null;
                    return fi.GetValue(obj);
                }

                public static EventDatum Create(object obj, EventDescriptor desc)
                {
                    EventHandlerList list = GetEvents(obj);
                    if (list == null)
                        return null;
                    object key = GetEventID(obj, desc.Name);
                    if (key == null)
                        return null;
                    Delegate evnt = list[key];
                    if (evnt == null)
                        return null;
                    return new EventDatum(desc, evnt);
                }

                #endregion

                #region Constructors
                internal EventDatum(EventDescriptor desc, Delegate aEvent)
                {
                    _eventDesc = desc;
                    _event = aEvent;
                }
                #endregion

                public void Wire(object obj)
                {
                    _eventDesc.AddEventHandler(obj, _event);
                }

                public void Unwire(object obj)
                {
                    _eventDesc.RemoveEventHandler(obj, _event);
                }
            }
        }

 

 

這個克隆方法的優點是既copy了原control的屬性,又copy了原control的事件.

 

現在放出代碼,希望對大家有所幫助.