C#WPF读取文本

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;
using System.IO;

namespace WpfApplication2
{
    /// <summary>
    /// Interaction logic for Window1.xaml
    /// </summary>
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
            StreamReader sr = new StreamReader("E:\\Project(vs)\\WpfApplication2\\xsdf.txt", Encoding.GetEncoding("GB2312"));
            string str = "";
         String line;
         while ((line = sr.ReadLine()) != null)
         {
             str +=  line.ToString() + "\r\n";

         }
         textBox1.Text = str;

        }
    }
}