C#操作Oracle的blob

using System;
using Fjeptri.DataAccess.DataHelper;
using System.Data.OracleClient;
using System.Data;
using System.IO;
using System.Windows.Forms;
using blank;

namespace WindowsApplication1
{
 /// <summary>
 /// Blob 的摘要说明。
 /// </summary>
 public class Blob
 {
  public Blob()
  {
   //
   // TODO: 在此处添加构造函数逻辑
   //
  }

  public void InsertBlob() //插入Blob内容
  {
   //获取提交数据库的文件内容。
   OracleLob blob = this.GetTempBLobs();

   //文件内容是否为空
   if(blob.IsNull)
   {return;}

   //向数据库提交内容。
   OracleConnection conn = new OracleConnection(ConfigInfo.GetConnectionString());
   if(conn.State == ConnectionState.Closed)
   {
    conn.Open();
   }
   OracleTransaction transaction =conn.BeginTransaction();
   string Create="insert into tablewithlobs(a,b) values(tablewithlobs_seq.nextval,:Blob)";
   OracleParameter[] param=new OracleParameter[1];
   param[0]=new OracleParameter("Blob",OracleType.Blob);
   param[0].Value = blob;
   OracleHelper.ExecuteNonQuery(transaction,CommandType.Text,Create,param);
   transaction.Commit();
   conn.Close();
  }

  private OracleLob GetTempBLobs() //获取提交数据库的文件内容
  {
   //输入文件内容
   Stream stream = Stream.Null;
   OpenFileDialog openFileDialog = new OpenFileDialog();
   string fileName = openFileDialog.FileName;
   openFileDialog.CheckFileExists = true;
   if (openFileDialog.ShowDialog() == DialogResult.OK)
   {
    stream = openFileDialog.OpenFile(); 
   }
   else
   {
    return OracleLob.Null;
   }
   stream.Position =0 ;
   byte[] byte_buffer = new byte[stream.Length];
   for(int i=0;i<stream.Length;i++)
   {
    byte_buffer[i]=(byte)stream.ReadByte();
   }
   
   //创建临时Blob变量
   OracleType lobtype=OracleType.Blob;
   string CreateTempBlob= "DECLARE A " + lobtype + "; "+
    "BEGIN "+
    "DBMS_LOB.CREATETEMPORARY(A, FALSE); "+
    ":LOC := A; "+
    "END;";
   
   OracleConnection conn = new OracleConnection(ConfigInfo.GetConnectionString());
   if(conn.State == ConnectionState.Closed)
   {
    conn.Open();
   }
   OracleTransaction transaction = conn.BeginTransaction();
   OracleParameter[] param=new OracleParameter[1];
   param[0]=new OracleParameter("LOC",OracleType.Blob);
   OracleHelper.CacheParameter(CreateTempBlob,param);
   param[0].Direction = ParameterDirection.Output;
   OracleHelper.ExecuteNonQuery(transaction,CommandType.Text,CreateTempBlob,param);
   OracleLob tempLob = (OracleLob)param[0].Value;

   //将文件内容传入Blob变量
   tempLob.BeginBatch(OracleLobOpenMode.ReadWrite);
   tempLob.Write(byte_buffer,0,byte_buffer.Length);
   tempLob.Position = 0;
   conn.Close();
   return tempLob;
  }

  public void ReadBLob(decimal A) //读出Blob内容
  {
   //从数据库读出内容
   string Read = "select b from tablewithlobs where a =:a";
   OracleParameter[] param=OracleHelper.GetCacheParameter(Read);
   if(param==null)
   {
    param=new OracleParameter[1];
    param[0]=new OracleParameter("a",OracleType.Number);
    OracleHelper.CacheParameter(Read,param);
   }
   param[0].Value = A;
   OracleDataReader dr = OracleHelper.ExecuteReader(ConfigInfo.GetConnectionString(),CommandType.Text,Read,param);
   OracleLob blob = OracleLob.Null;
   while(dr.Read())
   {
    blob = dr.GetOracleLob(0);
   }
   
   //打开保存内容的文件
   string filename =string.Empty;
   byte[] buffer=null;
   SaveFileDialog saveFileDialog = new SaveFileDialog();
   if(saveFileDialog.ShowDialog() == DialogResult.OK)
   {
    filename = saveFileDialog.FileName;
   }
   if(filename == string.Empty)
   {
    MessageBox.Show("请确定保存的文件路径！");
    return;
   }

   //将Blob类型的内容转化成文件流类型
   buffer = new byte[blob.Length];
   blob.Read(buffer,0,buffer.Length);

   //将内容写入文件
   FileStream fs= new FileStream(filename,FileMode.OpenOrCreate);
   fs.Write(buffer,0,buffer.Length);
   fs.Close();
  }

  public void UpdateBlob(decimal A) //更新Blob内容
  {
   //提交更新的文件内容
   Stream stream = Stream.Null;
   OpenFileDialog openFileDialog = new OpenFileDialog();
   string fileName = openFileDialog.FileName;
   openFileDialog.CheckFileExists = true;
   if (openFileDialog.ShowDialog() == DialogResult.OK)
   {
    stream = openFileDialog.OpenFile();
   }
   else
   {
    return;
   }
   
   //获取要更新的数据库内容
   string Update = "select b from tablewithlobs where a =:a for update";
   OracleConnection conn = new OracleConnection(ConfigInfo.GetConnectionString());
   conn.Open();
   OracleTransaction transaction = conn.BeginTransaction();
   OracleParameter[] param=OracleHelper.GetCacheParameter(Update);
   if(param==null)
   {
    param=new OracleParameter[1];
    param[0]=new OracleParameter("a",OracleType.Number);
    OracleHelper.CacheParameter(Update,param);
   }
   param[0].Value = A;
   OracleDataReader dr = OracleHelper.ExecuteReader(transaction,CommandType.Text,Update,param);
   OracleLob blob = OracleLob.Null;
   while(dr.Read())
   {
    blob = dr.GetOracleLob(0);
   }
   
   //向数据库写入更新内容
   stream.Position =0 ;
   byte[] byte_buffer = new byte[stream.Length];
   for(int i=0;i<stream.Length;i++)
   {
    byte_buffer[i]=(byte)stream.ReadByte();
   }
   blob.Write(byte_buffer,0,byte_buffer.Length);
   transaction.Commit();
   conn.Close();
   stream.Close();

  }

  public void DeleteBlob(decimal A) //删除Blob内容
  {
   OracleConnection conn = new OracleConnection(ConfigInfo.GetConnectionString());
   conn.Open();
   OracleTransaction transaction = conn.BeginTransaction();
   string Delete="delete tablewithlobs where a=:a";
   OracleParameter[] param=OracleHelper.GetCacheParameter(Delete);
   if(param==null)
   {
    param=new OracleParameter[1];
    param[0]=new OracleParameter("a",OracleType.Number);
    OracleHelper.CacheParameter(Delete,param);
   }
   param[0].Value=A;
   OracleHelper.ExecuteNonQuery(transaction,CommandType.Text,Delete,param);
   transaction.Commit();
   conn.Close();
   MessageBox.Show("删除成功！");
  }
 }
}