C#winform向Txt文件传值，不重复录入且不清空

private void textLog_TextChanged(object sender, EventArgs e)

{

FileStream fs = new FileStream(@"C:\\文件导入记录日志.txt", FileMode.Open);

StreamReader Reader = new StreamReader(fs);

string strLine = Reader.ReadLine();

while (strLine!=null && strLine!="")

{

strLine = Reader.ReadLine();

}

StreamWriter sw = new StreamWriter(fs);

sw.WriteLine(strLine+textLog.Text);

sw.Flush();

sw.Close();

fs.Close();

}