Daok 建议的 MS 文章让我走上了正轨，但我对 MS 的 SortableSearchableList 实现并不满意。我发现这个实现很奇怪，当列中有重复值时它不能很好地工作。它也不会覆盖 DataGridView 似乎需要的 IsSortedCore。如果 IsSortedCore 未被覆盖，则不会出现搜索字形，并且无法在升序和降序之间切换。
请参阅下面我的 SortableSearchableList 版本。在 ApplySortCore() 中，它使用设置为匿名方法的比较委托进行排序。此版本还支持为特定属性设置自定义比较，可以由派生类使用 AddCustomCompare() 添加。
我不确定版权声明是否仍然适用，但我只是把它留在了里面。
//---------------------------------------------------------------------
// Copyright (C) Microsoft Corporation. All rights reserved.
//
//THIS CODE AND INFORMATION ARE PROVIDED AS IS WITHOUT WARRANTY OF ANY
//KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
//IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A
//PARTICULAR PURPOSE.
//---------------------------------------------------------------------
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Reflection;
using System.Collections;
namespace SomethingSomething
{
/// <summary>
/// Supports sorting of list in data grid view.
/// </summary>
/// <typeparam name="T">Type of object to be displayed in data grid view.</typeparam>
public class SortableSearchableList<T> : BindingList<T>
{
#region Data Members
private ListSortDirection _sortDirectionValue;
private PropertyDescriptor _sortPropertyValue = null;
/// <summary>
/// Dictionary from property name to custom comparison function.
/// </summary>
private Dictionary<string, Comparison<T>> _customComparisons = new Dictionary<string, Comparison<T>>();
#endregion
#region Constructors
/// <summary>
/// Default constructor.
/// </summary>
public SortableSearchableList()
{
}
#endregion
#region Properties
/// <summary>
/// Indicates if sorting is supported.
/// </summary>
protected override bool SupportsSortingCore
{
get
{
return true;
}
}
/// <summary>
/// Indicates if list is sorted.
/// </summary>
protected override bool IsSortedCore
{
get
{
return _sortPropertyValue != null;
}
}
/// <summary>
/// Indicates which property the list is sorted.
/// </summary>
protected override PropertyDescriptor SortPropertyCore
{
get
{
return _sortPropertyValue;
}
}
/// <summary>
/// Indicates in which direction the list is sorted on.
/// </summary>
protected override ListSortDirection SortDirectionCore
{
get
{
return _sortDirectionValue;
}
}
#endregion
#region Methods
/// <summary>
/// Add custom compare method for property.
/// </summary>
/// <param name="propertyName"></param>
/// <param name="compareProperty"></param>
protected void AddCustomCompare(string propertyName, Comparison<T> comparison)
{
_customComparisons.Add(propertyName, comparison);
}
/// <summary>
/// Apply sort.
/// </summary>
/// <param name="prop"></param>
/// <param name="direction"></param>
protected override void ApplySortCore(PropertyDescriptor prop, ListSortDirection direction)
{
Comparison<T> comparison;
if (!_customComparisons.TryGetValue(prop.Name, out comparison))
{
// Check to see if the property type we are sorting by implements
// the IComparable interface.
Type interfaceType = prop.PropertyType.GetInterface("IComparable");
if (interfaceType != null)
{
comparison = delegate(T t1, T t2)
{
IComparable val1 = (IComparable)prop.GetValue(t1);
IComparable val2 = (IComparable)prop.GetValue(t2);
return val1.CompareTo(val2);
};
}
else
{
// Last option: convert to string and compare.
comparison = delegate(T t1, T t2)
{
string val1 = prop.GetValue(t1).ToString();
string val2 = prop.GetValue(t2).ToString();
return val1.CompareTo(val2);
};
}
}
if (comparison != null)
{
// If so, set the SortPropertyValue and SortDirectionValue.
_sortPropertyValue = prop;
_sortDirectionValue = direction;
// Create sorted list.
List<T> _sortedList = new List<T>(this);
_sortedList.Sort(comparison);
// Reverse order if needed.
if (direction == ListSortDirection.Descending)
{
_sortedList.Reverse();
}
// Update list.
int count = this.Count;
for (int i = 0; i < count; i++)
{
this[i] = _sortedList[i];
}
// Raise the ListChanged event so bound controls refresh their
// values.
OnListChanged(new ListChangedEventArgs(ListChangedType.Reset, -1));
}
}
// Method below was in the original implementation from MS. Don't know what it's for.
// -- Martijn Boeker, Jan 21, 2010
//protected override void RemoveSortCore()
//{
// //int position;
// //object temp;
// //// Ensure the list has been sorted.
// //if (unsortedItems != null)
// //{
// // // Loop through the unsorted items and reorder the
// // // list per the unsorted list.
// // for (int i = 0; i < unsortedItems.Count; )
// // {
// // position = this.Find(SortPropertyCore.Name,
// // unsortedItems[i].GetType().
// // GetProperty(SortPropertyCore.Name).
// // GetValue(unsortedItems[i], null));
// // if (position >= 0 && position != i)
// // {
// // temp = this[i];
// // this[i] = this[position];
// // this[position] = (T)temp;
// // i++;
// // }
// // else if (position == i)
// // i++;
// // else
// // // If an item in the unsorted list no longer exists, delete it.
// // unsortedItems.RemoveAt(i);
// // }
// // OnListChanged(new ListChangedEventArgs(ListChangedType.Reset, -1));
// //}
//}
/// <summary>
/// Ability to search an item.
/// </summary>
protected override bool SupportsSearchingCore
{
get
{
return true;
}
}
/// <summary>
/// Finds an item in the list.
/// </summary>
/// <param name="prop"></param>
/// <param name="key"></param>
/// <returns></returns>
protected override int FindCore(PropertyDescriptor prop, object key)
{
// Implementation not changed from MS example code.
// Get the property info for the specified property.
PropertyInfo propInfo = typeof(T).GetProperty(prop.Name);
T item;
if (key != null)
{
// Loop through the the items to see if the key
// value matches the property value.
for (int i = 0; i < Count; ++i)
{
item = (T)Items[i];
if (propInfo.GetValue(item, null).Equals(key))
return i;
}
}
return -1;
}
/// <summary>
/// Finds an item in the list.
/// </summary>
/// <param name="prop"></param>
/// <param name="key"></param>
/// <returns></returns>
private int Find(string property, object key)
{
// Implementation not changed from MS example code.
// Check the properties for a property with the specified name.
PropertyDescriptorCollection properties =
TypeDescriptor.GetProperties(typeof(T));
PropertyDescriptor prop = properties.Find(property, true);
// If there is not a match, return -1 otherwise pass search to
// FindCore method.
if (prop == null)
return -1;
else
return FindCore(prop, key);
}
#endregion
}
}