C#读取大文件(四)

    }    
            prgLoader.Value = 100;    
            lblShowPercent.Text = prgLoader.Value.ToString() +  "%" ;    
            btnOk.Text =  "关闭" ;    
         }    
        }    
         else     
        {    
          if (intCount == 0)    
         {    
            strSelect = strTargetSelect;    
            sqlcmd.CommandText = strSelect;    
            bytContent =  new   byte [intLength];    
            bytContent = sqlcmd.ExecuteScalar()  as   byte [];    
            fs.Write(bytContent,0,intLength);    
         }    
          else     
         {    
             int  i = 0;    
            bytContent =  new   byte [intBlock];    
             while (i < intCount)    
            {    
             strSelect =  "declare @content varbinary(16) " ;  //再sql中声明获取目标image列内容的句柄变量    
             strSelect += strTargetHandle;  //获取句柄    
              //锁定并读取指定长度的数据    
             strSelect +=  " readtext "  + strTableName +  "."  + strColumnName +  " @content @start @count HOLDLOCK" ;    
              if (i == 0)    
             {    
                 //添加@start和@count变量，分别表偏移变量和取的长度    
                sqlcmd.Parameters.Add( "@start" ,System.Data.SqlDbType.Int).Value = 0;     
                sqlcmd.Parameters.Add( "@count" ,System.Data.SqlDbType.Int).Value = intBlock;    
             }    
              else     
             {    
                sqlcmd.Parameters[ "@start" ].Value = i * intBlock;    
                sqlcmd.Parameters[ "@count" ].Value = intBlock;    
             }    
             sqlcmd.CommandText = strSelect;    
             bytContent = sqlcmd.ExecuteScalar()  as   byte [];    
 fs.Write(bytContent,0,intBlock);    
             ++i;    
 
            }    
             //将剩余的字节写入流    
             int  intResidual = intLength % intBlock;    
             if (intResidual > 0)    
            {    
             strSelect =  "declare @content varbinary(16) " ;  //再sql中声明获取目标image列内容的句柄变量    
             strSelect += strTargetHandle;  //获取句柄    
              //锁定并读取指定长度的数据    
             strSelect +=  " readtext "  + strTableName +  "."  + strColumnName +  " @content @start @count HOLDLOCK" ;    
             bytContent =  new   byte [intResidual];    
             sqlcmd.Parameters[ "@start" ].Value = intCount * intBlock;    
             sqlcmd.Parameters[ "@count" ].Value = intResidual;    
             sqlcmd.CommandText = strSelect;    
             bytContent = sqlcmd.ExecuteScalar()  as   byte [];    
             fs.Write(bytContent,0,intResidual);    
 
            }    
         }    
 
        }    
         bytContent =  null ;    
         fs.Close();    
     }    
      catch     
     {    
            state = 0;    
            System.IO.File.Delete(strPath);    
                                    bytContent =  null ;    
                                    fs.Close();    
             return   false ;    
     }    
     state = 0;    
      return   true ;    

    }

本文转自 BruceAndLee 51CTO博客，原文链接：http://blog.51cto.com/leelei/194147，如需转载请自行联系原作者