Using System.Text;

byte[ ] 转换为string

byte[ ] image;

string ll = Encoding.Default.GetString(image);

string 转换为byte[ ]
string ss;

byte[] b = Encoding.Default.GetBytes(ss);

数据库中image类型的字段的处理。

首先我想从数据库中读出图片（以image类型存储的), 并且写入txt文件中：

private void GetImage()

  {

    string conn = "Server=192.168.0.11; User id=user; Pwd=pwd; Database=database";

    SqlConnection sqlCon = new SqlConnection(conn);

    string sql = "SELECT ImageFile, PersonID FROM Persons where PersonID = 1";

    SqlCommand myCommand = new SqlCommand();

    myCommand.Connection = sqlCon;

    myCommand.CommandType = CommandType.Text;

    myCommand.CommandText = sql;

    DataTable myTable = new DataTable();

    SqlDataAdapter myDataAda = new SqlDataAdapter();

    myDataAda.SelectCommand = myCommand;

    try

    {

      sqlCon.Open();

      myDataAda.Fill(myTable);

      sqlCon.Close();

      if(myTable.Rows.Count>0)

      {

        byte[] image = (byte[])myTable.Rows[0]["ImageFile"];

        string ll = Encoding.Default.GetString(image);

        WriteStr(@"F:\test.txt",ll);

      }

    }

    catch(Exception ex)

    {

      string err = ex.Message;

    }

    finally

    {

      sqlCon.Close();

      myCommand.Dispose();

      myDataAda.Dispose();

    }

  }

  private void WriteStr(string strLogFileName, string strLogContent)

  {

    try

    {

      FileInfo objFileInfo = new FileInfo(strLogFileName);

      using (FileStream objFileStream = objFileInfo.OpenWrite())

      {

        using (StreamWriter objStreamWriter = new StreamWriter(objFileStream))

        {

          objStreamWriter.BaseStream.Seek(0, SeekOrigin.End);

          objStreamWriter.Write("{0}", strLogContent);

        }

      }

    }

    catch

    {

    }

  }
其次，需要把图片从txt文件中读出然后存入数据库中。

string ss = ReadStr(@"F:\test.txt");

    byte[] b = Encoding.Default.GetBytes(ss);

    string conn = "Server=server; User id=user; Pwd=pwd; Database=database";

    SqlConnection sqlCon = new SqlConnection(conn);

    string sql = "update Persons set ImageFile=@img where PersonID = 1";

    SqlCommand myCommand = new SqlCommand();

    SqlParameter sp = new SqlParameter("@img",SqlDbType.Image);

    myCommand.Connection = sqlCon;

    myCommand.CommandType = CommandType.Text;

    myCommand.CommandText = sql;

    sp.Value = b;

    myCommand.Parameters.Add(sp);

    try

    {

      sqlCon.Open();

      myCommand.ExecuteNonQuery();

      sqlCon.Close();

    }

    catch(Exception eS)

    {

      string ee = eS.Message;

    }

    finally

    {

      sqlCon.Close();

      myCommand.Dispose();

    }

 

Stream To Byte[]

 public static byte[] StreamToByte(Stream Reader)

        {

            try

            {

                MemoryStream mem = new MemoryStream(1024 * 500);

                byte[] buffer = new byte[1024];

                int bytesRead = 0;

                int TotalByteRead = 0;

                while (true)

                {

                    bytesRead = Reader.Read(buffer, 0, buffer.Length);

                    if (bytesRead == 0)

                        break;

                    TotalByteRead += bytesRead;

                    mem.Write(buffer, 0, buffer.Length);

                }

                if (mem.Length > 0)

                {

                    return mem.ToArray();

                }

                else

                {

                    return null;

                }

            }

            catch (Exception ep)

            {

                throw ep;

            }

        }