我写过无数的扩展方法，这里有几个我觉得特别有用的。请随意执行。
public static class ControlExtenders
{
/// <summary>
/// Advanced version of find control.
/// </summary>
/// <typeparam name="T">Type of control to find.</typeparam>
/// <param name="id">Control id to find.</param>
/// <returns>Control of given type.</returns>
/// <remarks>
/// If the control with the given id is not found
/// a new control instance of the given type is returned.
/// </remarks>
public static T FindControl<T>(this Control control, string id) where T : Control
{
// User normal FindControl method to get the control
Control _control = control.FindControl(id);
// If control was found and is of the correct type we return it
if (_control != null && _control is T)
{
// Return new control
return (T)_control;
}
// Create new control instance
_control = (T)Activator.CreateInstance(typeof(T));
// Add control to source control so the
// next it is found and the value can be
// passed on itd, remember to hide it and
// set an ID so it can be found next time
if (!(_control is ExtenderControlBase))
{
_control.Visible = false;
}
_control.ID = id;
control.Controls.Add(_control);
// Use reflection to create a new instance of the control
return (T)_control;
}
}
public static class GenericListExtenders
{
/// <summary>
/// Sorts a generic list by items properties.
/// </summary>
/// <typeparam name="T">Type of collection.</typeparam>
/// <param name="list">Generic list.</param>
/// <param name="fieldName">Field to sort data on.</param>
/// <param name="sortDirection">Sort direction.</param>
/// <remarks>
/// Use this method when a dinamyc sort field is requiered. If the
/// sorting field is known manual sorting might improve performance.
/// </remarks>
public static void SortObjects<T>(this List<T> list, string fieldName, SortDirection sortDirection)
{
PropertyInfo propInfo = typeof(T).GetProperty(fieldName);
if (propInfo != null)
{
Comparison<T> compare = delegate(T a, T b)
{
bool asc = sortDirection == SortDirection.Ascending;
object valueA = asc ? propInfo.GetValue(a, null) : propInfo.GetValue(b, null);
object valueB = asc ? propInfo.GetValue(b, null) : propInfo.GetValue(a, null);
return valueA is IComparable ? ((IComparable)valueA).CompareTo(valueB) : 0;
};
list.Sort(compare);
}
}
/// <summary>
/// Creates a pagged collection from generic list.
/// </summary>
/// <typeparam name="T">Type of collection.</typeparam>
/// <param name="list">Generic list.</param>
/// <param name="sortField">Field to sort data on.</param>
/// <param name="sortDirection">Sort direction.</param>
/// <param name="from">Page from item index.</param>
/// <param name="to">Page to item index.</param>
/// <param name="copy">Creates a copy and returns a new list instead of changing the current one.</param>
/// <returns>Pagged list collection.</returns>
public static List<T> Page<T>(this List<T> list, string sortField, bool sortDirection, int from, int to, bool copy)
{
List<T> _pageList = new List<T>();
// Copy list
if (copy)
{
T[] _arrList = new T[list.Count];
list.CopyTo(_arrList);
_pageList = new List<T>(_arrList);
}
else
{
_pageList = list;
}
// Make sure there are enough items in the list
if (from > _pageList.Count)
{
int diff = Math.Abs(from - to);
from = _pageList.Count - diff;
}
if (to > _pageList.Count)
{
to = _pageList.Count;
}
// Sort items
if (!string.IsNullOrEmpty(sortField))
{
SortDirection sortDir = SortDirection.Descending;
if (!sortDirection) sortDir = SortDirection.Ascending;
_pageList.SortObjects(sortField, sortDir);
}
// Calculate max number of items per page
int count = to - from;
if (from + count > _pageList.Count) count -= (from + count) - _pageList.Count;
// Get max number of items per page
T[] pagged = new T[count];
_pageList.CopyTo(from, pagged, 0, count);
// Return pagged items
return new List<T>(pagged);
}
/// <summary>
/// Shuffle's list items.
/// </summary>
/// <typeparam name="T">List type.</typeparam>
/// <param name="list">Generic list.</param>
public static void Shuffle<T>(this List<T> list)
{
Random rng = new Random();
for (int i = list.Count - 1; i > 0; i--)
{
int swapIndex = rng.Next(i + 1);
if (swapIndex != i)
{
T tmp = list[swapIndex];
list[swapIndex] = list[i];
list[i] = tmp;
}
}
}
/// <summary>
/// Converts generic List to DataTable.
/// </summary>
/// <typeparam name="T">Type.</typeparam>
/// <param name="list">Generic list.</param>
/// <param name="columns">Name of the columns to copy to the DataTable.</param>
/// <returns>DataTable.</returns>
public static DataTable ToDataTable<T>(this List<T> list, string[] columns)
{
List<string> _columns = new List<string>(columns);
DataTable dt = new DataTable();
foreach (PropertyInfo info in typeof(T).GetProperties())
{
if (_columns.Contains(info.Name) || columns == null)
{
dt.Columns.Add(new DataColumn(info.Name, info.PropertyType));
}
}
foreach (T t in list)
{
DataRow row = dt.NewRow();
foreach (PropertyInfo info in typeof(T).GetProperties())
{
if (_columns.Contains(info.Name) || columns == null)
{
row[info.Name] = info.GetValue(t, null);
}
}
dt.Rows.Add(row);
}
return dt;
}
}
public static class DateTimeExtenders
{
/// <summary>
/// Returns number of month from a string representation.
/// </summary>
/// <returns>Number of month.</returns>
public static int MonthToNumber(this DateTime datetime, string month)
{
month = month.ToLower();
for (int i = 1; i <= 12; i++)
{
DateTime _dt = DateTime.Parse("1." + i + ".2000");
string _month = CultureInfo.InvariantCulture.DateTimeFormat.GetMonthName(i).ToLower();
if (_month == month)
{
return i;
}
}
return 0;
}
/// <summary>
/// Returns month name from month number.
/// </summary>
/// <returns>Name of month.</returns>
public static string MonthToName(this DateTime datetime, int month)
{
for (int i = 1; i <= 12; i++)
{
if (i == month)
{
return CultureInfo.InvariantCulture.DateTimeFormat.GetMonthName(i);
}
}
return "";
}
}
public static class ObjectExtender
{
public static object CloneBinary<T>(this T originalObject)
{
using (var stream = new System.IO.MemoryStream())
{
BinaryFormatter binaryFormatter = new BinaryFormatter();
binaryFormatter.Serialize(stream, originalObject);
stream.Position = 0;
return (T)binaryFormatter.Deserialize(stream);
}
}
public static object CloneObject(this object obj)
{
using (MemoryStream memStream = new MemoryStream())
{
BinaryFormatter binaryFormatter = new BinaryFormatter(null, new StreamingContext(StreamingContextStates.Clone));
binaryFormatter.Serialize(memStream, obj);
memStream.Position = 0;
return binaryFormatter.Deserialize(memStream);
}
}
}
public static class StringExtenders
{
/// <summary>
/// Returns string as unit.
/// </summary>
/// <param name="value">Value.</param>
/// <returns>Unit</returns>
public static Unit ToUnit(this string value)
{
// Return empty unit
if (string.IsNullOrEmpty(value))
return Unit.Empty;
// Trim value
value = value.Trim();
// Return pixel unit
if (value.EndsWith("px"))
{
// Set unit type
string _int = value.Replace("px", "");
// Try parsing to int
double _val = 0;
if (!double.TryParse(_int, out _val))
{
// Invalid value
return Unit.Empty;
}
// Return unit
return new Unit(_val, UnitType.Pixel);
}
// Return percent unit
if (value.EndsWith("%"))
{
// Set unit type
string _int = value.Replace("%", "");
// Try parsing to int
double _val = 0;
if (!double.TryParse(_int, out _val))
{
// Invalid value
return Unit.Empty;
}
// Return unit
return new Unit(_val, UnitType.Percentage);
}
// No match found
return new Unit();
}
/// <summary>
/// Returns alternative string if current string is null or empty.
/// </summary>
/// <param name="str"></param>
/// <param name="alternative"></param>
/// <returns></returns>
public static string Alternative(this string str, string alternative)
{
if (string.IsNullOrEmpty(str)) return alternative;
return str;
}
/// <summary>
/// Removes all HTML tags from string.
/// </summary>
/// <param name="html">String containing HTML tags.</param>
/// <returns>String with no HTML tags.</returns>
public static string StripHTML(this string html)
{
string nohtml = Regex.Replace(html, "<(.|\n)*?>", "");
nohtml = nohtml.Replace("\r\n", "").Replace("\n", "").Replace(" ", "").Trim();
return nohtml;
}
}
第一个是我最喜欢的，因为它可以代替:
Control c = this.FindControl("tbName");
if (c != null)
{
// Do something with c
customer.Name = ((TextBox)c).Text;
}
用这个:
TextBox c = this.FindControl<TextBox>("tbName");
customer.Name = c.Text;
设置默认字符串值:
string str = "";
if (string.IsNullOrEmpty(str))
{
str = "I'm empty!";
}
就变成:
str = str.Alternative("I'm empty!");
