.NET 2.0下简单的FTP访问程序
[简介]
也许大家也不想总依赖着第三方FTP软件，值得高兴的是，本文将给你开发出一套免费的来。尽管，本文中的代码没有设计成可重用性很高的库，不过确实是一个简单的可以重复使用部分代码的程序。本文最大的目的是演示如何在.NET 2.0中使用C#设计FTP访问程序。
[代码使用]
添加以下命名空间：
Code:
using System.Net;
using System.IO;
using System.IO;
下面的步骤可以看成，使用 FtpWebRequest对象发送FTP请求的一般步骤：
1. 创建一个带有ftp服务器Uri的FtpWebRequest对象
2. 设置FTP的执行模式（上传、下载等）
3. 设置ftp webrequest选项（支持ssl，作为binary传输等）
4. 设置登陆帐号
5. 执行请求
6. 接收响应流（如果需要的话）
7. 关闭FTP请求，并关闭任何已经打开的数据流
首先，创建一个uri，它包括ftp地址、文件名（目录结构），这个uri将被用于创建 FtpWebRequest 实例。
设置 FtpWebRequest 对象的属性，这些属性决定ftp请求的设置。一些重用的属性如下：
Credentials ：用户名、密码
KeepAlive ：是否在执行完请求之后，就关闭。默认，设置为true
UseBinary ：传输文件的数据格式Binary 还是ASCII。
UsePassive ：主动还是被动模式，早期的ftp，主动模式下，客户端会正常工作；不过，如今，大部分端口都已经被封掉了，导致主动模式会失败。
Contentlength ：这个值经常被忽略，不过如果你设置的话，还是对服务器有帮助的，至少让它事先知道用户期望的文件是多大。
Method ：决定本次请求的动作（upload, download, filelist 等等）
上传文件
private
void
Upload(
string
filename)
{
FileInfo fileInf = new FileInfo(filename);
string uri = " ftp:// " + ftpServerIP + " / " + fileInf.Name;
FtpWebRequest reqFTP;
// Create FtpWebRequest object from the Uri provided
reqFTP = (FtpWebRequest)FtpWebRequest.Create( new Uri(
" ftp:// " + ftpServerIP + " / " + fileInf.Name));
// Provide the WebPermission Credintials
reqFTP.Credentials = new NetworkCredential(ftpUserID,
ftpPassword);
// By default KeepAlive is true, where the control connection is
// not closed after a command is executed.
reqFTP.KeepAlive = false ;
// Specify the command to be executed.
reqFTP.Method = WebRequestMethods.Ftp.UploadFile;
// Specify the data transfer type.
reqFTP.UseBinary = true ;
// Notify the server about the size of the uploaded file
reqFTP.ContentLength = fileInf.Length;
// The buffer size is set to 2kb
int buffLength = 2048 ;
byte [] buff = new byte [buffLength];
int contentLen;
// Opens a file stream (System.IO.FileStream) to read
the file to be uploaded
FileStream fs = fileInf.OpenRead();
try
{
// Stream to which the file to be upload is written
Stream strm = reqFTP.GetRequestStream();
// Read from the file stream 2kb at a time
contentLen = fs.Read(buff, 0 , buffLength);
// Till Stream content ends
while (contentLen != 0 )
{
// Write Content from the file stream to the
// FTP Upload Stream
strm.Write(buff, 0 , contentLen);
contentLen = fs.Read(buff, 0 , buffLength);
}
// Close the file stream and the Request Stream
strm.Close();
fs.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message, " Upload Error " );
}
}
{
FileInfo fileInf = new FileInfo(filename);
string uri = " ftp:// " + ftpServerIP + " / " + fileInf.Name;
FtpWebRequest reqFTP;
// Create FtpWebRequest object from the Uri provided
reqFTP = (FtpWebRequest)FtpWebRequest.Create( new Uri(
" ftp:// " + ftpServerIP + " / " + fileInf.Name));
// Provide the WebPermission Credintials
reqFTP.Credentials = new NetworkCredential(ftpUserID,
ftpPassword);
// By default KeepAlive is true, where the control connection is
// not closed after a command is executed.
reqFTP.KeepAlive = false ;
// Specify the command to be executed.
reqFTP.Method = WebRequestMethods.Ftp.UploadFile;
// Specify the data transfer type.
reqFTP.UseBinary = true ;
// Notify the server about the size of the uploaded file
reqFTP.ContentLength = fileInf.Length;
// The buffer size is set to 2kb
int buffLength = 2048 ;
byte [] buff = new byte [buffLength];
int contentLen;
// Opens a file stream (System.IO.FileStream) to read
the file to be uploaded
FileStream fs = fileInf.OpenRead();
try
{
// Stream to which the file to be upload is written
Stream strm = reqFTP.GetRequestStream();
// Read from the file stream 2kb at a time
contentLen = fs.Read(buff, 0 , buffLength);
// Till Stream content ends
while (contentLen != 0 )
{
// Write Content from the file stream to the
// FTP Upload Stream
strm.Write(buff, 0 , contentLen);
contentLen = fs.Read(buff, 0 , buffLength);
}
// Close the file stream and the Request Stream
strm.Close();
fs.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message, " Upload Error " );
}
}
上面的代码用于 上传文件，设置FtpWebRequest 到ftp服务器上指定的文件，并设置其它属性。打开本地文件，把其内容写入FTP请求数据流。
下载文件：
private
void
Download(
string
filePath,
string
fileName)
{
FtpWebRequest reqFTP;
try
{
// filePath = <<The full path where the
// file is to be created. the>>,
// fileName = <<Name of the file to be createdNeed not
// name on FTP server. name name()>>
FileStream outputStream = new FileStream(filePath +
" \\ " + fileName, FileMode.Create);
reqFTP = (FtpWebRequest)FtpWebRequest.Create( new Uri( " ftp:// " +
ftpServerIP + " / " + fileName));
reqFTP.Method = WebRequestMethods.Ftp.DownloadFile;
reqFTP.UseBinary = true ;
reqFTP.Credentials = new NetworkCredential(ftpUserID,
ftpPassword);
FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();
Stream ftpStream = response.GetResponseStream();
long cl = response.ContentLength;
int bufferSize = 2048 ;
int readCount;
byte [] buffer = new byte [bufferSize];
readCount = ftpStream.Read(buffer, 0 , bufferSize);
while (readCount > 0 )
{
outputStream.Write(buffer, 0 , readCount);
readCount = ftpStream.Read(buffer, 0 , bufferSize);
}
ftpStream.Close();
outputStream.Close();
response.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
{
FtpWebRequest reqFTP;
try
{
// filePath = <<The full path where the
// file is to be created. the>>,
// fileName = <<Name of the file to be createdNeed not
// name on FTP server. name name()>>
FileStream outputStream = new FileStream(filePath +
" \\ " + fileName, FileMode.Create);
reqFTP = (FtpWebRequest)FtpWebRequest.Create( new Uri( " ftp:// " +
ftpServerIP + " / " + fileName));
reqFTP.Method = WebRequestMethods.Ftp.DownloadFile;
reqFTP.UseBinary = true ;
reqFTP.Credentials = new NetworkCredential(ftpUserID,
ftpPassword);
FtpWebResponse response = (FtpWebResponse)reqFTP.GetResponse();
Stream ftpStream = response.GetResponseStream();
long cl = response.ContentLength;
int bufferSize = 2048 ;
int readCount;
byte [] buffer = new byte [bufferSize];
readCount = ftpStream.Read(buffer, 0 , bufferSize);
while (readCount > 0 )
{
outputStream.Write(buffer, 0 , readCount);
readCount = ftpStream.Read(buffer, 0 , bufferSize);
}
ftpStream.Close();
outputStream.Close();
response.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
上面是从FTP 下载文件的示例代码，与上传不一样，这里需要一个响应数据流（response stream），它包括文件请求的内容。使用FtpWebRequest 类中的 GetResponse() 函数得到数据。
获取文件列表
public
string
[] GetFileList()
{
string [] downloadFiles;
StringBuilder result = new StringBuilder();
FtpWebRequest reqFTP;
try
{
reqFTP = (FtpWebRequest)FtpWebRequest.Create( new Uri(
" ftp:// " + ftpServerIP + " / " ));
reqFTP.UseBinary = true ;
reqFTP.Credentials = new NetworkCredential(ftpUserID,
ftpPassword);
reqFTP.Method = WebRequestMethods.Ftp.ListDirectory;
WebResponse response = reqFTP.GetResponse();
StreamReader reader = new StreamReader(response
.GetResponseStream());
string line = reader.ReadLine();
while (line != null )
{
result.Append(line);
result.Append( " \n " );
line = reader.ReadLine();
}
// to remove the trailing '\n'
result.Remove(result.ToString().LastIndexOf( ' \n ' ), 1 );
reader.Close();
response.Close();
return result.ToString().Split( ' \n ' );
}
catch (Exception ex)
{
System.Windows.Forms.MessageBox.Show(ex.Message);
downloadFiles = null ;
return downloadFiles;
}
}
{
string [] downloadFiles;
StringBuilder result = new StringBuilder();
FtpWebRequest reqFTP;
try
{
reqFTP = (FtpWebRequest)FtpWebRequest.Create( new Uri(
" ftp:// " + ftpServerIP + " / " ));
reqFTP.UseBinary = true ;
reqFTP.Credentials = new NetworkCredential(ftpUserID,
ftpPassword);
reqFTP.Method = WebRequestMethods.Ftp.ListDirectory;
WebResponse response = reqFTP.GetResponse();
StreamReader reader = new StreamReader(response
.GetResponseStream());
string line = reader.ReadLine();
while (line != null )
{
result.Append(line);
result.Append( " \n " );
line = reader.ReadLine();
}
// to remove the trailing '\n'
result.Remove(result.ToString().LastIndexOf( ' \n ' ), 1 );
reader.Close();
response.Close();
return result.ToString().Split( ' \n ' );
}
catch (Exception ex)
{
System.Windows.Forms.MessageBox.Show(ex.Message);
downloadFiles = null ;
return downloadFiles;
}
}
上面是得到ftp服务器上的指定路径下的文件列表，Uri被指定为Ftp服务器名称、端口以及目录结构。
对于FTP服务器上文件的 重命名， 删除， 获取文件大小， 文件详细信息， 创建目录等等操作于上面类似，你很容易地理解本文中的代码。
