openFileDialog1.Filter = "文本文件(*.txt)|*.txt";//设置过滤参数
openFileDialog1.ShowDialog();//显示打开文件的对话框
textBox1.Text = openFileDialog1.FileName;
StreamReader sr = new StreamReader(textBox1.Text, Encoding.Default);
textBox2.Text = sr.ReadLine();
sr.Close();