C#修改文件中的行内容

//修改文件内容的方法（多少行，修改为的内容，文件路径）
public void EditFile(int curLine, string newLineValue, string patch)
{
FileStream fs = new FileStream(patch, FileMode.Open, FileAccess.Read);
StreamReader sr = new StreamReader(fs, Encoding.GetEncoding("utf-8"));
string line = sr.ReadLine();
StringBuilder sb = new StringBuilder();
for (int i = 1; line != null; i++)
{
sb.Append(line + "\r\n");
if (i != curLine - 1)
line = sr.ReadLine();
else
{
sr.ReadLine();
line = newLineValue;
}
}
sr.Close();
fs.Close();
FileStream fs1 = new FileStream(patch, FileMode.Open, FileAccess.Write);
StreamWriter sw = new StreamWriter(fs1, Encoding.GetEncoding("utf-8"));
sw.Write(sb.ToString());
sw.Close();
fs1.Close();
}