WPF中怎样将一个Textbox中的内容保存为txt【附源代码】

<Window x:Class="Test.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:Test"
mc:Ignorable="d"
Title="MainWindow" Height="350" Width="525">
<Grid>
<TextBox x:Name="textBox1" HorizontalAlignment="Left" Height="23" Margin="146,108,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Width="120"/>
<Button x:Name="button1" Content="Button" HorizontalAlignment="Left" Margin="198,186,0,0" VerticalAlignment="Top" Width="75" Click="button1_Click"/>

</Grid>
</Window>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
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;
using System.IO;//添加引用

namespace Test
{
/// <summary>
/// MainWindow.xaml 的交互逻辑
/// </summary>
public partial class MainWindow : Window
{
public MainWindow()
{
InitializeComponent();
}

private void button1_Click(object sender, RoutedEventArgs e)
{
WriteFile("E:\\123.txt", textBox1.Text);
}
/// <summary>
/// 写文件
/// </summary>
/// <param name="Path">文件路径</param>
/// <param name="Strings">文件内容</param>
public static void WriteFile(string Path, string Strings)
{
if (!System.IO.File.Exists(Path))
{
//Directory.CreateDirectory(Path);
System.IO.FileStream f = System.IO.File.Create(Path);
f.Close();
f.Dispose();
}
System.IO.StreamWriter f2 = new System.IO.StreamWriter(Path, true, System.Text.Encoding.UTF8);
f2.WriteLine(Strings);
f2.Close();
f2.Dispose();
}
}
}