.NET学习之文字转码

最近项目中需要用到了附件图片查看审批功能，业务申请的时候图片默认是上传到FTP的，由于之前没有写过处理FTP的文件，我需要将图片的路径绑到插件中去，我原本思路是直接把FTP路径放进去，结果发现不行，我以为是路径中中文编码有问题，所以我试了各种编码转换，结果一个后台大哥和我说，处理FTP文件都是先在后台启动一个FTP服务，将文件在本地有一个备份，再将本地的文件路径返回到页面上去，可怜我犯傻了一天，试了各种编码。

再次验证了写逻辑代码，一定要清楚功能是在前台处理还是在后台处理，要不然容易出乱子，今天就是，我当时在浏览器中直接可以访问FTP协议路径下的文件，没有输入帐号密码之类的，所以我以为是页面局部标签渲染，也是可以直接访问这个路径，结果浪费了一天时间，想想也是，服务器中的文件不用帐号密码就可以直接访问和下载，文件安全性得不到保证。

/// <summary>
/// GB2312转换成UTF8
/// </summary>
/// <param name="text"></param>
/// <returns></returns>
public static string gb2312_utf8(string text)
{
  //声明字符集
  System.Text.Encoding utf8, gb2312;
  //gb2312
  gb2312 = System.Text.Encoding.GetEncoding("gb2312");
  //utf8
  utf8 = System.Text.Encoding.GetEncoding("utf-8");
  byte[] gb;
  gb = gb2312.GetBytes(text);
  gb = System.Text.Encoding.Convert(gb2312, utf8, gb);
  //返回转换后的字符
  return utf8.GetString(gb);
}

/// <summary>
/// UTF8转换成GB2312
/// </summary>
/// <param name="text"></param>
/// <returns></returns>
public static string utf8_gb2312(string text)
{
  //声明字符集
  System.Text.Encoding utf8, gb2312;
  //utf8
  utf8 = System.Text.Encoding.GetEncoding("utf-8");
  //gb2312
  gb2312 = System.Text.Encoding.GetEncoding("gb2312");
  byte[] utf;
  utf = utf8.GetBytes(text);
  utf = System.Text.Encoding.Convert(utf8, gb2312, utf);
  //返回转换后的字符
  return gb2312.GetString(utf);
}

/// <summary>
/// UTF8转换成gbk
/// </summary>
/// <param name="text"></param>
/// <returns></returns>
public static string utf8_gbk(string text)
{
  //声明字符集
  System.Text.Encoding utf8, gbk;
  //utf8
  utf8 = System.Text.Encoding.GetEncoding("utf-8");
  //gb2312
  gbk = System.Text.Encoding.GetEncoding("gbk");
  byte[] utf;
  utf = utf8.GetBytes(text);
  utf = System.Text.Encoding.Convert(utf8, gbk, utf);
  //返回转换后的字符
  return gbk.GetString(utf);
}


  public static int Asc(string character)
  {
      if (character.Length == 1)
      {
          System.Text.ASCIIEncoding asciiEncoding = new System.Text.ASCIIEncoding();
          int intAsciiCode = (int)asciiEncoding.GetBytes(character)[0];
          return (intAsciiCode);
      }
      else
      {
          throw new Exception("Character is not valid.");
      }
  }

      //显示图片
      private void GetFJImg(HttpContext context)
      {

          if (!string.IsNullOrEmpty(sSQBH) && !string.IsNullOrEmpty(sFJMC))
          {
              //定义FTP请求对象
              FtpWebRequest reqFTP = null;
              //定义FTP响应对象
              FtpWebResponse response = null;
              //FTP数据流
              Stream ftpStream = null;
              MemoryStream outStream = new MemoryStream();
              try
              {
                  if (string.IsNullOrEmpty(sFTPLJ))
                  {
                      Stream stream = new MemoryStream(byteFTPNR);
                      int bufferSize = 2048;
                      byte[] buffer = new byte[bufferSize];
                      int contentLen = stream.Read(buffer, 0, bufferSize);
                      while (contentLen != 0)
                      {
                          outStream.Write(buffer, 0, contentLen);
                          contentLen = stream.Read(buffer, 0, bufferSize);
                      }
                      stream.Close();


                  }
                  else
                  {
                      //FTP模式
                      string filePath = string.Empty;
                      string URL = ConfigurationManager.AppSettings["FtpAddr"];
                      string username = ConfigurationManager.AppSettings["FtpUser"];
                      string password = ConfigurationManager.AppSettings["FtpPwd"];
                      filePath = "ftp://" + URL + "/" + sSQBH + "/" + sFJMC;
                      reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri(filePath));
                      reqFTP.Method = WebRequestMethods.Ftp.DownloadFile;
                      reqFTP.UseBinary = true;
                      reqFTP.Credentials = new NetworkCredential(username, password);
                      response = (FtpWebResponse)reqFTP.GetResponse();
                      ftpStream = response.GetResponseStream();
                      int bufferSize = 2048;
                      byte[] buffer = new byte[bufferSize];
                      int contentLen = ftpStream.Read(buffer, 0, bufferSize);
                      while (contentLen != 0)
                      {
                          outStream.Write(buffer, 0, contentLen);
                          contentLen = ftpStream.Read(buffer, 0, bufferSize);
                      }
                      ftpStream.Close();

                  }
                  context.Response.ContentType = "image/GIF";
                  context.Response.Cache.SetCacheability(HttpCacheability.Public);
                  context.Response.BufferOutput = false;
                  context.Response.BinaryWrite(outStream.ToArray());
                  context.Response.Flush();
              }
              catch (Exception ex)
              {
                  ILog log = new ErrorLog(this.GetType());
                  log.WriteLog(ex, "GetFJImg获取图片信息出错!", ex.Message);
              }
              finally
              {
                  if (response != null)
                  {
                      response.Close();
                  }
                  if (ftpStream != null)
                  {
                      ftpStream.Close();
                  }
              }
          }
      }