如何通过FTP上传文件到服务器

下面的代码示例演示了使用异步操作将文件上传到FTP服务器。

using System;
using System.Net;
using System.Threading;
using System.IO;
namespace Examples.System.Net
{
    public class FtpState
    {
        private ManualResetEvent wait;
        private FtpWebRequest request;
        private string fileName;
        private Exception operationException = null;
        string status;
        public FtpState()
        {
            wait = new ManualResetEvent(false);
        }
        public ManualResetEvent OperationComplete
        {
            get {return wait;}
        }
        public FtpWebRequest Request
        {
            get {return request;}
            set {request = value;}
        }
        public string FileName
        {
            get {return fileName;}
            set {fileName = value;}
        }
        public Exception OperationException
        {
            get {return operationException;}
            set {operationException = value;}
        }
        public string StatusDescription
        {
            get {return status;}
            set {status = value;}
        }
    }
    public class AsynchronousFtpUpLoader
    {  
        // Command line arguments are two strings: 
        // 1. The url that is the name of the file being uploaded to the server. 
        // 2. The name of the file on the local machine. 
        // 
        public static void Main(string[] args)
        {
            // Create a Uri instance with the specified URI string. 
            // If the URI is not correctly formed, the Uri constructor 
            // will throw an exception.
            ManualResetEvent waitObject;
            Uri target = new Uri (args[0]);
            string fileName = args[1];
            FtpState state = new FtpState();
            FtpWebRequest request = (FtpWebRequest)WebRequest.Create(target);
            request.Method = WebRequestMethods.Ftp.UploadFile;
            // This example uses anonymous logon. 
            // The request is anonymous by default; the credential does not have to be specified.  
            // The example specifies the credential only to 
            // control how actions are logged on the server.
            request.Credentials = new NetworkCredential ("anonymous","janeDoe@contoso.com");
            // Store the request in the object that we pass into the 
            // asynchronous operations.
            state.Request = request;
            state.FileName = fileName;
            // Get the event to wait on.
            waitObject = state.OperationComplete;
            // Asynchronously get the stream for the file contents.
            request.BeginGetRequestStream(
                new AsyncCallback (EndGetStreamCallback), 
                state
            );
            // Block the current thread until all operations are complete.
            waitObject.WaitOne();
            // The operations either completed or threw an exception. 
            if (state.OperationException != null)
            {
                throw state.OperationException;
            }
            else
            {
                Console.WriteLine("The operation completed - {0}", state.StatusDescription);
            }
        }
        private static void EndGetStreamCallback(IAsyncResult ar)
        {
            FtpState state = (FtpState) ar.AsyncState;
            Stream requestStream = null;
            // End the asynchronous call to get the request stream. 
            try
            {
                requestStream = state.Request.EndGetRequestStream(ar);
                // Copy the file contents to the request stream. 
                const int bufferLength = 2048;
                byte[] buffer = new byte[bufferLength];
                int count = 0;
                int readBytes = 0;
                FileStream stream = File.OpenRead(state.FileName);
                do
                {
                    readBytes = stream.Read(buffer, 0, bufferLength);
                    requestStream.Write(buffer, 0, readBytes);
                    count += readBytes;
                }
                while (readBytes != 0);
                Console.WriteLine ("Writing {0} bytes to the stream.", count);
                // IMPORTANT: Close the request stream before sending the request.
                requestStream.Close();
                // Asynchronously get the response to the upload request.
                state.Request.BeginGetResponse(
                    new AsyncCallback (EndGetResponseCallback), 
                    state
                );
            } 
            // Return exceptions to the main application thread. 
            catch (Exception e)
            {
                Console.WriteLine("Could not get the request stream.");
                state.OperationException = e;
                state.OperationComplete.Set();
                return;
            }
        }
        // The EndGetResponseCallback method   
        // completes a call to BeginGetResponse. 
        private static void EndGetResponseCallback(IAsyncResult ar)
        {
            FtpState state = (FtpState) ar.AsyncState;
            FtpWebResponse response = null;
            try 
            {
                response = (FtpWebResponse) state.Request.EndGetResponse(ar);
                response.Close();
                state.StatusDescription = response.StatusDescription;
                // Signal the main application thread that  
                // the operation is complete.
                state.OperationComplete.Set();
            }
            // Return exceptions to the main application thread. 
            catch (Exception e)
            {
                Console.WriteLine ("Error getting response.");
                state.OperationException = e;
                state.OperationComplete.Set();
            }
        }
    }
}

看看FtpWebRequest:第三个例子展示了如何执行上传。

(文件的大小没有真正的区别，除了网络问题有更多的机会中断它。)