Java-Programs/ftpserver.java at master · Vigneshwaran07/Java-Programs · GitHub

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import java.net.*;
import java.io.*;
import java.util.*;

public class fserver
{
    public static void main(String args[]) throws Exception
    {
        ServerSocket soc=new ServerSocket(5218);
        System.out.println("FTP Server Started on Port Number 5218");
        while(true)
        {
            System.out.println("Waiting for Connection ...");
            transferfile t=new transferfile(soc.accept());

        }
    }
}

class transferfile extends Thread
{
    Socket ClientSoc;

    DataInputStream din;
    DataOutputStream dout;

    transferfile(Socket soc)
    {
        try
        {
            ClientSoc=soc;
            din=new DataInputStream(ClientSoc.getInputStream());
            dout=new DataOutputStream(ClientSoc.getOutputStream());
            System.out.println("FTP Client Connected ...");
            start();

        }
        catch(Exception ex)
        {
        }
    }
    void SendFile() throws Exception
    {
        String filename=din.readUTF();
        File f=new File(filename);
        if(!f.exists())
        {
            dout.writeUTF("File Not Found");
            return;
        }
        else
        {
            dout.writeUTF("READY");
            FileInputStream fin=new FileInputStream(f);
            int ch;
            do
            {
                ch=fin.read();
                dout.writeUTF(String.valueOf(ch));
            }
            while(ch!=-1);
            fin.close();
            dout.writeUTF("File Receive Successfully");
        }
    }

    void ReceiveFile() throws Exception
    {
        String filename=din.readUTF();
        if(filename.compareTo("File not found")==0)
        {
            return;
        }
        File f=new File(filename);
        String option;

        if(f.exists())
        {
            dout.writeUTF("File Already Exists");
            option=din.readUTF();
        }
        else
        {
            dout.writeUTF("SendFile");
            option="Y";
        }

            if(option.compareTo("Y")==0)
            {
                FileOutputStream fout=new FileOutputStream(f);
                int ch;
                String temp;
                do
                {
                    temp=din.readUTF();
                    ch=Integer.parseInt(temp);
                    if(ch!=-1)
                    {
                        fout.write(ch);
                    }
                }while(ch!=-1);
                fout.close();
                dout.writeUTF("File Send Successfully");
            }
            else
            {
                return;
            }

    }


    public void run()
    {
        while(true)
        {
            try
            {
            System.out.println("Waiting for Command ...");
            String Command=din.readUTF();
            if(Command.compareTo("GET")==0)
            {
                System.out.println("\tGET Command Received ...");
                SendFile();
                continue;
            }
            else if(Command.compareTo("SEND")==0)
            {
                System.out.println("\tSEND Command Receiced ...");
                ReceiveFile();
                continue;
            }
            else if(Command.compareTo("DISCONNECT")==0)
            {
                System.out.println("\tDisconnect Command Received ...");
                System.exit(1);
            }
            }
            catch(Exception ex)
            {
            }
        }
    }
}