C# 文件同时读写

//文件冲突测试
FileStream fs1 = new FileStream("readtest1.txt", FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
int i1 = fs1.ReadByte();
FileStream fs2 = new FileStream("readtest1.txt",FileMode.Open,FileAccess.Read,FileShare.ReadWrite);

textBox1.Text = i1.ToString()+"\r\n";

FileStream fs3 = new FileStream("readtest1.txt", FileMode.Create,FileAccess.Write);
fs3.WriteByte(24);
fs3.Flush();
int i2 = fs2.ReadByte();
textBox1.Text += i2.ToString();
fs3.Close();
fs2.Close();
fs1.Close();