具体不做详细介绍了，直接上代码

/// <summary>
  /// 功能：FileStream文件流读取文件
  /// </summary>
  /// <param name="filePath">参数：文件路径</param>
  /// <returns>返回值：StreamReader对象</returns>
  public static StreamReader ReadFileByFs(string filePath)
  {
   FileStream Fs = null;
   StreamReader Sr = null;
   try
   {
    Fs = new FileStream(filePath, FileMode.OpenOrCreate, FileAccess.Read);
    Sr = new StreamReader(Fs, Encoding.Default);
   }
   catch (IOException e)
   {
    throw e;
   }
   return Sr;
  }

　　代码 2：
      

 /// <summary>
  /// 功能：FileStream文件流写文件
  /// </summary>
  /// <param name="filePath">参数：文件路径</param>
  /// <returns>返回值：StreamWriter对象</returns>
  public static StreamWriter WriteFileByFs(string filePath)
  {
   FileStream Fs = null;
   StreamWriter Sw = null;
   try
   {
    Fs = new FileStream(filePath, FileMode.OpenOrCreate, FileAccess.Write);
    Sw = new StreamWriter(Fs, Encoding.Default);
   }
   catch (IOException e)
   {
    throw e;
   }
   return Sw;
  }

以上代码针对IO读写文件方法封装做了详细介绍，希望能够帮助到大家。