C#操作本地文件及保存文件到数据库的基本方法总结

using System.IO;

StreamWriter sw=File.CreateText("c:\\text.txt");  
sw.WriteLine("C#");                //写入一行文本 
sw.Write("www.csdn.net");             //在文本末尾写入文本 
sw.Flush();                    //清空 
sw.Close();                    //关闭 

StreamReader sr = File.OpenText("c:\\text.txt"); 
sr.ReadLine();                  //读取一行数据 
sr.Read();                    //读取一个字符 
sr.ReadToEnd();                  //从当前位置读取到文本结束 
sr.Close();                    //释放资源 

StreamWriter sw = File.AppendText("c:\\text.txt"); 
sw.WriteLine("C#");                 //写入一行文本 
sw.Write("www.csdn.net");              //在文本末尾写入文本 
sw.Flush();                     //清空 
sw.Close();                     //关闭 

File.Exists("c:\\text.txt"); 

File.Delete("c:\\text.txt"); 

File.Copy("c:\\text.txt", "c:\\copy.txt");   //把c:\\text.txt复制到c:\\copy.txt 

File.Copy("c:\\text.txt", "d:\\text.txt");  //把c:\\text.txt移动到d:\\text.txt 

Directory.Delete("c:\\test");       //删除C盘下的test文件夹 
Directory.CreateDirectory("c:\\test");  //在C盘创建test文件夹 
Directory.Exists("c:\\test");       //验证C盘test文件夹是否存在 
Directory.Move("c:\\test", "d:\\test");  //把c:\test移动到d:\test 

create table tb_file 
( 
 id       number(20) not null, 
 file_name    nvarchar2(100), 
 file_content  blob, 
 constraint pk_tb_file primary key (id) 
) 
tablespace mydb storage( 
 initial 64K 
 minextents 1 
 maxextents unlimited 
); 

create sequence seq_tb_file  --创建自增序列 
minvalue 1 
maxvalue 9999999999999999999 
start with 1 
increment by 1 
nocache 
order; 
 
create or replace trigger ai_tb_file --创建触发器，当插入新记录时自增主键id 
before insert on tb_file 
for each row 
when (new.id is null) 
begin 
select seq_tb_file.nextval into :new.id from dual; 
end; 

//添加命名空间 
using System; 
using System.Data.OracleClient; 
using System.IO; 
using System.Data; 
 
/// <summary> 
/// 把文件插入数据库中 
/// </summary> 
/// <param name="filePath">文件名，包含路径，如c:\temp.rar</param> 
/// <returns></returns> 
public int Insert(string filePath) 
{ 
  string connStr = "data source=orcl;user=mydbuser;password=mydbuser;"; 
  OracleConnection conn = new OracleConnection(connStr); 
  OracleCommand cmd = conn.CreateCommand(); 
 
  //读取文件 
  FileStream fs = File.OpenRead(filePath); 
  byte[] buffer = new byte[fs.Length]; 
  fs.Read(buffer, 0, buffer.Length); 
 
  OracleParameter paramFileContent = cmd.CreateParameter(); 
  paramFileContent.OracleType = OracleType.Blob; 
  paramFileContent.ParameterName = "FileContent"; 
  paramFileContent.Direction = ParameterDirection.Input; 
  paramFileContent.Value = buffer; 
  cmd.Parameters.Add(paramFileContent); 
 
  OracleParameter paramFileName = cmd.CreateParameter(); 
  paramFileName.OracleType = OracleType.VarChar; 
  paramFileName.ParameterName = "FileName"; 
  paramFileName.Direction = ParameterDirection.Input; 
  paramFileName.Value = Path.GetFileName(filePath); 
  cmd.Parameters.Add(paramFileName); 
 
  string sqlInsert = "insert into tb_file (file_name, file_content) values (:FileName, :FileContent)"; 
  cmd.CommandText = sqlInsert; 
  cmd.CommandType = CommandType.Text; 
 
  conn.Open(); 
  int result = cmd.ExecuteNonQuery(); 
  conn.Close(); 
 
  return result; 
} 
 
 
/// <summary> 
/// 根据文件名从数据库中获取文件 
/// </summary> 
/// <param name="fileName">数据库中的文件名</param> 
/// <param name="savePath">文件的保存路径，包括文件名，如c:\file.rar</param> 
public void Select(string fileName, string savePath) 
{ 
  string connStr = "data source=orcl;user=mydbuser;password=mydbuser;"; 
  OracleConnection conn = new OracleConnection(connStr); 
  OracleCommand cmd = conn.CreateCommand(); 
 
  string sqlSelect = "select file_name, file_content from tb_file where file_name=:FileName"; 
  cmd.CommandText = sqlSelect; 
  cmd.CommandType = CommandType.Text; 
 
  OracleParameter paramFileName = cmd.CreateParameter(); 
  paramFileName.OracleType = OracleType.VarChar; 
  paramFileName.ParameterName = "FileName"; 
  paramFileName.Direction = ParameterDirection.Input; 
  paramFileName.Value = fileName; 
  cmd.Parameters.Add(paramFileName);       
 
  conn.Open(); 
  OracleDataReader dr = cmd.ExecuteReader(); 
  dr.Read(); 
  byte[] buffer = (byte[])dr["file_content"]; 
  dr.Close(); 
  conn.Close(); 
 
  //把文件保存到指定路径 
  File.WriteAllBytes(savePath, buffer); 
}