在Winform中当我们对输入内容有限制。。比如说必须是时间呀。。货币呀。。。等等时，我们或许可以使用MaskedTextBox,但是在WPF中不存在这个控件。。所以我们可以自己写一个这样的空间作为用户空间来使用它。。。

下面就是一个自写的MaskedTextBox全码：

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.ComponentModel;using System.Windows;using System.Windows.Controls;using System.Windows.Data;using System.Windows.Documents;using System.Windows.Input;using System.Windows.Media;using System.Windows.Media.Imaging;using System.Windows.Navigation;using System.Windows.Shapes;namespace MaskedTextBox.Control{    public class MaskedTextBox : TextBox    {        public static readonly DependencyProperty InputMaskProperty;        private List<InputMaskChar> _maskChars;        private int _caretIndex;        static MaskedTextBox()        {            TextProperty.OverrideMetadata(typeof(MaskedTextBox),                new FrameworkPropertyMetadata(null, new CoerceValueCallback(Text_CoerceValue)));            InputMaskProperty = DependencyProperty.Register("InputMask", typeof(string), typeof(MaskedTextBox),                new PropertyMetadata(string.Empty, new PropertyChangedCallback(InputMask_Changed)));        }        public MaskedTextBox()        {            this._maskChars = new List<InputMaskChar>();            DataObject.AddPastingHandler(this, new DataObjectPastingEventHandler(MaskedTextBox_Paste));        }        /// <summary>        /// Get or Set the input mask.        /// </summary>        public string InputMask        {            get { return this.GetValue(InputMaskProperty) as string; }            set { this.SetValue(InputMaskProperty, value); }        }        [Flags]        protected enum InputMaskValidationFlags        {            None = 0,            AllowInteger = 1,            AllowDecimal = 2,            AllowAlphabet = 4,            AllowAlphanumeric = 8        }        /// <summary>        /// Returns a value indicating if the current text value is valid.        /// </summary>        /// <returns></returns>        public bool IsTextValid()        {            string value;            return this.ValidateTextInternal(this.Text, out value);        }        private class InputMaskChar        {            private InputMaskValidationFlags _validationFlags;            private char _literal;            public InputMaskChar(InputMaskValidationFlags validationFlags)            {                this._validationFlags = validationFlags;                this._literal = (char)0;            }            public InputMaskChar(char literal)            {                this._literal = literal;            }            public InputMaskValidationFlags ValidationFlags            {                get { return this._validationFlags; }                set { this._validationFlags = value; }            }            public char Literal            {                get { return this._literal; }                set { this._literal = value; }            }            public bool IsLiteral()            {                return (this._literal != (char)0);            }            public char GetDefaultChar()            {                return (this.IsLiteral()) ? this.Literal : ‘_‘;            }        }        protected override void OnInitialized(EventArgs e)        {            base.OnInitialized(e);            //DependencyPropertyDescriptor dpd = DependencyPropertyDescriptor.FromProperty(TextProperty, typeof(TextBox));            //if (dpd != null)            //{            //    dpd.AddValueChanged(this, delegate            //    {            //        this.UpdateInputMask();            //    });            //}        }        protected override void onm ouseUp(MouseButtonEventArgs e)        {            base.OnMouseUp(e);            this._caretIndex = this.CaretIndex;        }        protected override void OnPreviewKeyDown(KeyEventArgs e)        {            base.OnKeyDown(e);            //no mask specified, just function as a normal textbox            if (this._maskChars.Count == 0)                return;            if (e.Key == Key.Delete)            {                //delete key pressed: delete all text                this.Text = this.GetDefaultText();                this._caretIndex = this.CaretIndex = 0;                e.Handled = true;            }            else            {                //backspace key pressed                if (e.Key == Key.Back)                {                    if (this._caretIndex > 0 || this.SelectionLength > 0)                    {                        if (this.SelectionLength > 0)                        {                            //if one or more characters selected, delete them                            this.DeleteSelectedText();                        }                        else                        {                            //if no characters selected, shift the caret back to the previous non-literal char and delete it                            this.MoveBack();                            char[] characters = this.Text.ToCharArray();                            characters[this._caretIndex] = this._maskChars[this._caretIndex].GetDefaultChar();                            this.Text = new string(characters);                        }                        //update the base class caret index, and swallow the event                        this.CaretIndex = this._caretIndex;                        e.Handled = true;                    }                }                else if (e.Key == Key.Left)                {                    //move back to the previous non-literal character                    this.MoveBack();                    e.Handled = true;                }                else if (e.Key == Key.Right || e.Key == Key.Space)                {                    //move forwards to the next non-literal character                    this.MoveForward();                    e.Handled = true;                }            }        }        protected override void OnPreviewTextInput(TextCompositionEventArgs e)        {            base.OnPreviewTextInput(e);            //no mask specified, just function as a normal textbox            if (this._maskChars.Count == 0)                return;            this._caretIndex = this.CaretIndex = this.SelectionStart;            if (this._caretIndex == this._maskChars.Count)            {                //at the end of the character count defined by the input mask- no more characters allowed                e.Handled = true;            }            else            {                //validate the character against its validation scheme                bool isValid = this.ValidateInputChar(char.Parse(e.Text),                    this._maskChars[this._caretIndex].ValidationFlags);                if (isValid)                {                    //delete any selected text                    if (this.SelectionLength > 0)                    {                        this.DeleteSelectedText();                    }                    //insert the new character                    char[] characters = this.Text.ToCharArray();                    characters[this._caretIndex] = char.Parse(e.Text);                    this.Text = new string(characters);                    //move the caret on                     this.MoveForward();                }                e.Handled = true;            }        }        /// <summary>        /// Validates the specified character against all selected validation schemes.        /// </summary>        /// <param name="input"></param>        /// <param name="validationFlags"></param>        /// <returns></returns>        protected virtual bool ValidateInputChar(char input, InputMaskValidationFlags validationFlags)        {            bool valid = (validationFlags == InputMaskValidationFlags.None);            if (!valid)            {                Array values = Enum.GetValues(typeof(InputMaskValidationFlags));                //iterate through the validation schemes                foreach (object o in values)                {                    InputMaskValidationFlags instance = (InputMaskValidationFlags)(int)o;                    if ((instance & validationFlags) != 0)                    {                        if (this.ValidateCharInternal(input, instance))                        {                            valid = true;                            break;                        }                    }                }            }            return valid;        }        /// <summary>        /// Returns a value indicating if the current text value is valid.        /// </summary>        /// <returns></returns>        protected virtual bool ValidateTextInternal(string text, out string displayText)        {            if (this._maskChars.Count == 0)            {                displayText = text;                return true;            }            StringBuilder displayTextBuilder = new StringBuilder(this.GetDefaultText());            bool valid = (!string.IsNullOrEmpty(text) &&                text.Length <= this._maskChars.Count);            if (valid)            {                for (int i = 0; i < text.Length; i++)                {                    if (!this._maskChars[i].IsLiteral())                    {                        if (this.ValidateInputChar(text[i], this._maskChars[i].ValidationFlags))                        {                            displayTextBuilder[i] = text[i];                        }                        else                        {                            valid = false;                        }                    }                }            }            displayText = displayTextBuilder.ToString();            return valid;        }        /// <summary>        /// Deletes the currently selected text.        /// </summary>        protected virtual void DeleteSelectedText()        {            StringBuilder text = new StringBuilder(this.Text);            string defaultText = this.GetDefaultText();            int selectionStart = this.SelectionStart;            int selectionLength = this.SelectionLength;            text.Remove(selectionStart, selectionLength);            text.Insert(selectionStart, defaultText.Substring(selectionStart, selectionLength));            this.Text = text.ToString();            //reset the caret position            this.CaretIndex = this._caretIndex = selectionStart;        }        /// <summary>        /// Returns a value indicating if the specified input mask character is a placeholder.        /// </summary>        /// <param name="character"></param>        /// <param name="validationFlags">If the character is a placeholder, returns the relevant validation scheme.</param>        /// <returns></returns>        protected virtual bool IsPlaceholderChar(char character, out InputMaskValidationFlags validationFlags)        {            validationFlags = InputMaskValidationFlags.None;            switch (character.ToString().ToUpper())            {                case "I":                    validationFlags = InputMaskValidationFlags.AllowInteger;                    break;                case "D":                    validationFlags = InputMaskValidationFlags.AllowDecimal;                    break;                case "A":                    validationFlags = InputMaskValidationFlags.AllowAlphabet;                    break;                case "W":                    validationFlags = (InputMaskValidationFlags.AllowAlphanumeric);                    break;            }            return (validationFlags != InputMaskValidationFlags.None);        }        /// <summary>        /// Invoked when the coerce value callback is invoked.        /// </summary>        /// <param name="obj"></param>        /// <param name="e"></param>        private static object Text_CoerceValue(DependencyObject obj, object value)        {            MaskedTextBox mtb = (MaskedTextBox)obj;            if (value =http://www.mamicode.com/= null || value.Equals(string.Empty))                value = mtb.GetDefaultText();            else if (value.ToString().Length > 0)            {                string displayText;                mtb.ValidateTextInternal(value.ToString(), out displayText);                value = displayText;            }            return value;        }        /// <summary>        /// Invoked when the InputMask dependency property reports a change.        /// </summary>        /// <param name="obj"></param>        /// <param name="e"></param>        private static void InputMask_Changed(DependencyObject obj, DependencyPropertyChangedEventArgs e)        {            (obj as MaskedTextBox).UpdateInputMask();        }        /// <summary>        /// Invokes when a paste event is raised.        /// </summary>        /// <param name="sender"></param>        /// <param name="e"></param>        private void MaskedTextBox_Paste(object sender, DataObjectPastingEventArgs e)        {            //TODO: play nicely here?            //            if (e.DataObject.GetDataPresent(typeof(string)))            {                string value = http://www.mamicode.com/e.DataObject.GetData(typeof(string)).ToString();                string displayText;                if (this.ValidateTextInternal(value, out displayText))                {                    this.Text = displayText;                }            }            e.CancelCommand();        }        /// <summary>        /// Rebuilds the InputMaskChars collection when the input mask property is updated.        /// </summary>        private void UpdateInputMask()        {            string text = this.Text;            this._maskChars.Clear();            this.Text = string.Empty;            string mask = this.InputMask;            if (string.IsNullOrEmpty(mask))                return;            InputMaskValidationFlags validationFlags = InputMaskValidationFlags.None;            for (int i = 0; i < mask.Length; i++)            {                bool isPlaceholder = this.IsPlaceholderChar(mask[i], out validationFlags);                if (isPlaceholder)                {                    this._maskChars.Add(new InputMaskChar(validationFlags));                }                else                {                    this._maskChars.Add(new InputMaskChar(mask[i]));                }            }            string displayText;            if (text.Length > 0 && this.ValidateTextInternal(text, out displayText))            {                this.Text = displayText;            }            else            {                this.Text = this.GetDefaultText();            }        }        /// <summary>        /// Validates the specified character against its input mask validation scheme.        /// </summary>        /// <param name="input"></param>        /// <param name="validationType"></param>        /// <returns></returns>        private bool ValidateCharInternal(char input, InputMaskValidationFlags validationType)        {            bool valid = false;            switch (validationType)            {                case InputMaskValidationFlags.AllowInteger:                case InputMaskValidationFlags.AllowDecimal:                    int i;                    if (validationType == InputMaskValidationFlags.AllowDecimal &&                        input == ‘.‘ && !this.Text.Contains(‘.‘))                    {                        valid = true;                    }                    else                    {                        valid = int.TryParse(input.ToString(), out i);                    }                    break;                case InputMaskValidationFlags.AllowAlphabet:                    valid = char.IsLetter(input);                    break;                case InputMaskValidationFlags.AllowAlphanumeric:                    valid = (char.IsLetter(input) || char.IsNumber(input));                    break;            }            return valid;        }        /// <summary>        /// Builds the default display text for the control.        /// </summary>        /// <returns></returns>        private string GetDefaultText()        {            StringBuilder text = new StringBuilder();            foreach (InputMaskChar maskChar in this._maskChars)            {                text.Append(maskChar.GetDefaultChar());            }            return text.ToString();        }        /// <summary>        /// Moves the caret forward to the next non-literal position.        /// </summary>        private void MoveForward()        {            int pos = this._caretIndex;            while (pos < this._maskChars.Count)            {                if (++pos == this._maskChars.Count || !this._maskChars[pos].IsLiteral())                {                    this._caretIndex = this.CaretIndex = pos;                    break;                }            }        }        /// <summary>        /// Moves the caret backward to the previous non-literal position.        /// </summary>        private void MoveBack()        {            int pos = this._caretIndex;            while (pos > 0)            {                if (--pos == 0 || !this._maskChars[pos].IsLiteral())                {                    this._caretIndex = this.CaretIndex = pos;                    break;                }            }        }    }} 

<Window x:Class="TestApp.Window1"    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"    xmlns:ctrl="clr-namespace:MaskedTextBox.Control;assembly=MaskedTextBox.Control"        Title="Window1" Height="300" Width="300" Loaded="Window_Loaded">    <Grid>        <Grid.RowDefinitions>            <RowDefinition></RowDefinition>            <RowDefinition></RowDefinition>            <RowDefinition></RowDefinition>        </Grid.RowDefinitions>                <ctrl:MaskedTextBox Name="txt" InputMask="ii:ii" TextChanged="txt_TextChanged"></ctrl:MaskedTextBox>                <ctrl:MaskedTextBox Name="txt1" Grid.Row="1" InputMask="ii:ii" Text="{Binding Path=Time}" TextChanged="txt_TextChanged"></ctrl:MaskedTextBox>        <Border Grid.Row="2" Margin="115.69,30.167,98,30.167" BorderBrush="Black">            <TextBlock Name="txbStatus" HorizontalAlignment="Center" Foreground="Red" Height="18"></TextBlock>        </Border>    </Grid></Window>

using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Windows;using System.Windows.Controls;using System.Windows.Data;using System.Windows.Documents;using System.Windows.Input;using System.Windows.Media;using System.Windows.Media.Imaging;using System.Windows.Navigation;using System.Windows.Shapes;namespace TestApp{    /// <summary>    /// Interaction logic for Window1.xaml    /// </summary>    public partial class Window1 : Window    {        Booking _booking;        public Window1()        {            InitializeComponent();            //create a booking instance with a time of 12:00            this._booking = new Booking();            this._booking.Time = "12:00";        }        private void txt_TextChanged(object sender, TextChangedEventArgs e)        {            if (!this.IsLoaded) return;            bool valid = this.txt.IsTextValid();            this.txbStatus.Text = valid ? "VALID" : "INVALID";            this.txbStatus.Foreground = valid ? Brushes.Green : Brushes.Red;        }        private void Window_Loaded(object sender, RoutedEventArgs e)        {            //set the datacontext of the masked textbox            this.txt1.DataContext = this._booking;        }    }}

using System;using System.Collections.Generic;using System.Linq;using System.Text;namespace TestApp{    public class Booking    {        public string Time        {            get;            set;        }    }}