private void Button_Click(object sender, RoutedEventArgs e)
        {
            //最好使用WPF原生OpenFileDialog 
            Microsoft.Win32.OpenFileDialog openFileDialog = new Microsoft.Win32.OpenFileDialog();
            openFileDialog.Title = "选择文件";
            openFileDialog.Filter = "jpg|*.jpg|jpeg|*.jpeg";
            openFileDialog.FileName = string.Empty;
            openFileDialog.FilterIndex = 1;
            openFileDialog.RestoreDirectory = true;
            openFileDialog.DefaultExt = "jpg";
            bool? result = openFileDialog.ShowDialog();
            if (result !=true)
            {
                return;
            }
            string fileName = openFileDialog.FileName;
            this.textBox1.Text = fileName;
            BitmapImage image = new BitmapImage(new Uri(fileName));
            image1.Source = image;            
        }