java ftp文件服务器,java ftp文件服务器

Java提供了一些类和API来实现FTP文件服务器。以下是一个简单的FTP文件服务器的示例代码：

import java.io.*;
import java.net.*;
import org.apache.commons.net.ftp.*;

public class FTPServer {
   public static void main(String[] args) {
      FTPServer server = new FTPServer();
      server.start();
   }

   public void start() {
      int port = 21;
      try {
         ServerSocket serverSocket = new ServerSocket(port);
         System.out.println("FTP Server started on port " + port);

         while (true) {
            Socket clientSocket = serverSocket.accept();
            System.out.println("Accepted connection from " + clientSocket.getInetAddress().getHostAddress());

            FTPConnection connection = new FTPConnection(clientSocket);
            connection.start();
         }
      } catch (IOException ex) {
         System.err.println("Error starting FTP server: " + ex.getMessage());
      }
   }
}

class FTPConnection extends Thread {
   private Socket clientSocket;
   private FTPServer server;
   private FTPClient ftp;

   public FTPConnection(Socket clientSocket) {
      this.clientSocket = clientSocket;
      this.server = server;
      ftp = new FTPClient();
   }

   public void run() {
      try {
         ftp.connect(clientSocket.getInetAddress().getHostName());
         ftp.login("anonymous", "");
         ftp.enterLocalPassiveMode();

         BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
         PrintWriter out = new PrintWriter(new OutputStreamWriter(clientSocket.getOutputStream()));

         String line = null;
         out.print("220 FTP Server ready.\r\n");
         out.flush();

         while ((line = in.readLine()) != null) {
            if (line.startsWith("USER")) {
               out.print("331 Password required for " + line.substring(5) + "\r\n");
               out.flush();
            } else if (line.startsWith("PASS")) {
               out.print("230 User logged in.\r\n");
               out.flush();
            } else if (line.startsWith("QUIT")) {
               out.print("221 Goodbye.\r\n");
               out.flush();
               break;
            } else if (line.startsWith("TYPE")) {
               out.print("200 Command okay.\r\n");
               out.flush();
            } else if (line.startsWith("LIST")) {
               FTPFile[] files = ftp.listFiles();
               out.print("150 Opening ASCII mode data connection for file list.\r\n");
               out.flush();

               for (FTPFile file : files) {
                  out.print(file.getName() + "\r\n");
                  out.flush();
               }

               out.print("226 Transfer complete.\r\n");
               out.flush();
            } else if (line.startsWith("RETR")) {
               out.print("150 Opening BINARY mode data connection for " + line.substring(5) + "\r\n");
               out.flush();
               String fileName = line.substring(5);
               OutputStream os = clientSocket.getOutputStream();
               ftp.retrieveFile(fileName, os);
               out.print("226 Transfer complete.\r\n");
               out.flush();
            } else {
               out.print("502 Command not implemented.\r\n");
               out.flush();
            }
         }

         ftp.disconnect();
         clientSocket.close();
      } catch (IOException ex) {
         System.err.println("Error handling FTP connection: " + ex.getMessage());
      }
   }
}

这个例子使用Apache Commons Net库来实现FTP连接和文件传输。它可以处理一些基本的FTP命令，如USER、PASS、LIST和RETR。你可以根据需要添加更多的功能和命令来实现一个更完整的FTP文件服务器。