详解C#对路径...的访问被拒绝解决过程

  private void button1_Click(object sender, EventArgs e)
    {
      System.IO.StreamReader st;

//由于我的查询语句较长，采用了读取txt文本的方式后做查询操作。
      st = new System.IO.StreamReader(Application.StartupPath + "\\SQL2.txt", System.Text.Encoding.Default);
   
      string stingsql=st.ReadToEnd();
      st.Close();

      textBox1.Text = stingsql;
      DataTable dt = new DataTable();
      dt = bc.QueryCommand(stingsql);
   
      string filepath = @"F:\病案导出备份\患者统计表.csv";//此处必须为路径加文件名称，否则
      ImportToCSV(dt, filepath);
    }

    public static void ImportToCSV(DataTable dt, string filepath)
    {
      FileStream fs = null;
      StreamWriter sw = null;
      try
      {
        fs = new FileStream(filepath, FileMode.Create, FileAccess.Write);
        sw = new StreamWriter(fs, Encoding.Default);
        string head = "";
        //拼接列头
        for (int cNum = 0; cNum < dt.Columns.Count; cNum++)
        {
          head += dt.Columns[cNum].ColumnName + ",";
        }
        //csv文件写入列头
        sw.WriteLine(head);
        string data = "";
        //csv写入数据
        for (int i = 0; i < dt.Rows.Count; i++)
        {
          string data2 = string.Empty;
          //拼接行数据
          for (int cNum1 = 0; cNum1 < dt.Columns.Count; cNum1++)
          {
            data2 = data2 + "\"" + dt.Rows[i][dt.Columns[cNum1].ColumnName].ToString() + "\",";
          }
          bool flag = data != data2;
          if (flag)
          {
            sw.WriteLine(data2);
          }
          data = data2;

        }
        string msg = "数据被成功导出到：" + filepath;
        MessageBox.Show(msg);
      }
      catch (Exception ex)
      {
        // logger.Error("导出csv失败！" + ex.Message);

        MessageBox.Show("导出失败" + ex.Message);
        return;
      }
      finally
      {
        if (sw != null)
        {
          sw.Close();
        }
        if (fs != null)
        {
          fs.Close();
        }
        sw = null;
        fs = null;
      }
    }

 private bool GetChannelInfo()
 {
      comCheckWindow.LoadCheckResult("准备加载项目通道信息", Color.FromName("Green"));
      XmlDocument proFile = new XmlDocument(); //读取项目配置文件
      proFile.Load(proFilePath);
      XmlNodeList channelList = proFile.SelectSingleNode("Project").ChildNodes;
      if (channelList.Count == 0) return false;
      ......
      return true;
 }