C# txt文件写入，若不存在则生成文件，若存在则直接追加写入

C#txt文件写入，若不存在则生成文件，若存在则直接追加写入

if (!System.IO.File.Exists(path))
{
   FileStream fs1 = new FileStream(path, FileMode.Create,      
   FileAccess.Write);//创建写入文件 
   System.IO.File.SetAttributes(path, FileAttributes.ReadOnly); //设置文件属性为只读
   StreamWriter sw = new StreamWriter(fs1, Encoding.GetEncoding("utf-8"));
   sw.WriteLine("写入内容");//开始写入值
   sw.Close();
   fs1.Close();
 }
else
{
   new FileInfo(path).Attributes = FileAttributes.Normal;//获取文件的属性进行修改在操作
   FileStream fs1 = new FileStream(path, FileMode.Append, FileAccess.Write);//打开文件 
   StreamWriter sw = new StreamWriter(fs1, Encoding.GetEncoding("utf-8"));
   sw.WriteLine(error);//开始写入值
   sw.Close();
   fs1.Close();
}