Java Code For FTP Using UDP













//server
import java.io.*;
import java.net.*;

class FTPUDPS
{
    public static void main(String[] args)
    {
                DatagramSocket socket=null;
                //Send, Receive packets
                DatagramPacket inPacket=null;
                DatagramPacket outPacket=null;
                byte[] inBuf, outBuf;
                final int PORT=50000;

                try
                {
                        socket=new DatagramSocket(PORT);
                        while(true)
                        {
                                System.out.println("\nRunning...\n");

                                //Receive Client's request
                                inBuf=new byte[100];
                                inPacket=new DatagramPacket(inBuf, inBuf.length);
                                socket.receive(inPacket);

                                //Get Port and IPAddress
                                int source_port=inPacket.getPort();
                                InetAddress source_address=inPacket.getAddress();
                                System.out.println("Client: "+source_address + ":" + source_port);

                                //Send File list
                                String dirname="/home/vaibhav/TextFiles/";
                                File f1=new File(dirname);
                                File fl[]=f1.listFiles();

                                StringBuilder sb=new StringBuilder("\n");
                                int c=0;

                                for(int i=0;i<fl.length;i++)
                                {
                                        if(fl[i].canRead() && (fl[i].toString()).endsWith(".txt"))
                                        c++;
                                }

                                sb.append(c+" .txt files found.\n\n");

                                for(int i=0;i<fl.length;i++)
                                        if((fl[i].toString()).endsWith(".txt"))       
                                                sb.append(fl[i].getName()+" "+fl[i].length()+" Bytes\n");

                                sb.append("\nEnter file name for download: ");
                                outBuf=(sb.toString()).getBytes();
                                outPacket=new DatagramPacket(outBuf, 0, outBuf.length, source_address, source_port);
                                socket.send(outPacket);

                                //Receive Filename request
                                inBuf=new byte[100];
                                inPacket=new DatagramPacket(inBuf, inBuf.length);
                                socket.receive(inPacket);
                                String filename=new String(inPacket.getData(), 0, inPacket.getLength());

                                System.out.println("Requested File: "+filename);

                                boolean flis=false;
                                int index=-1;
                                sb=new StringBuilder("");
                                for(int i=0;i<fl.length;i++)
                                {
                                        if(((fl[i].getName()).toString()).equalsIgnoreCase(filename))
                                        {
                                                index=i;
                                                flis=true;
                                        }

                                }

                                if(!flis)
                                {
                                        System.out.println("ERROR");
                                        sb.append("ERROR");
                                        outBuf=(sb.toString()).getBytes();
                                        outPacket=new DatagramPacket(outBuf, 0, outBuf.length, source_address, source_port);
                                        socket.send(outPacket);
                                }
                                else
                                {
                                        try
                                        {
                                                //File Send Process, Independent
                                                File ff=new File(fl[index].getAbsolutePath());
                                                FileReader fr=new FileReader(ff);
                                                BufferedReader brf=new BufferedReader(fr);      
                                                String s=null;
                                                sb=new StringBuilder();

                                                while((s=brf.readLine())!=null)
                                                {
                                                        sb.append(s);
                                                }

                                                if(brf.readLine()==null)
                                                        System.out.println("File Read Successful. Closing Socket.");
                                                       
                                                outBuf=(sb.toString()).getBytes();
                                                outPacket=new DatagramPacket(outBuf, 0, outBuf.length, source_address, source_port);
                                                socket.send(outPacket);    
                                        }
                                        catch(IOException ioe)
                                        {
                                        System.out.println(ioe);
                                        }
                                }
                        }
                }
               
                catch(Exception e)
                {
                        System.out.println("Error\n");
                }
    }
}

//client
import java.io.*;
import java.net.*;
import java.util.Scanner;

class FTPUDPC
{
    public static void main(String[] args)
    {
                DatagramSocket socket = null;
                DatagramPacket inPacket = null;
                DatagramPacket outPacket = null;
                byte[] inBuf, outBuf;
                final int PORT = 50000;
                String msg = null;
                Scanner src=new Scanner(System.in);

                try
                {
                        InetAddress address = InetAddress.getByName("127.0.0.1");
                        socket = new DatagramSocket();

                        msg = "";
                        outBuf = msg.getBytes();
                        outPacket = new DatagramPacket(outBuf, 0, outBuf.length, address, PORT);
                        socket.send(outPacket);

                        inBuf = new byte[65535];
                        inPacket = new DatagramPacket(inBuf, inBuf.length);
                        socket.receive(inPacket);

                        String data = new String(inPacket.getData(), 0, inPacket.getLength());
                        //Print file list
                        System.out.println(data);

                        //Send file name
                        String filename=src.nextLine();             
                        outBuf = filename.getBytes();
                        outPacket = new DatagramPacket(outBuf, 0, outBuf.length,address, PORT);
                        socket.send(outPacket);

                        //Receive file
                        inBuf = new byte[100000];
                        inPacket = new DatagramPacket(inBuf, inBuf.length);
                        socket.receive(inPacket);

                        data = new String(inPacket.getData(), 0, inPacket.getLength());
                        if(data.endsWith("ERROR"))
                        {
                                System.out.println("File doesn't exist.\n");
                                socket.close();
                        }
                        else
                        {
                                try
                                {
                                        BufferedWriter pw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(filename)));
                                        pw.write(data);
                                        //Force write buffer to File
                                        pw.close();

                                        System.out.println("File Write Successful. Closing Socket.");
                                        socket.close();
                                }
                                       
                                catch(IOException ioe)
                                {
                                        System.out.println("File Error\n");
                                        socket.close();
                                }
                        }
                }
                catch (Exception e)
                {
                        System.out.println("\nNetwork error. Please try again.\n");
                }
    }
}

Java Code For FTP Using TCP














//Server
import java.io.*;
import java.net.*;
import java.util.Arrays;

class FileSend
{
        public static void main(String args[])
        {
                //Keep trying until Client connects.
                try
                {
                        ServerSocket serversocket=new ServerSocket(50000);
                        //Created ServerSocket on port 50000. Acknowledge client.
                        System.out.println("Running...");
                        //Accept incoming Client request.
                        Socket socket=serversocket.accept();
                        System.out.println("Client connected.");
                       
                        //Read and Write on Socket.
                        PrintWriter pw=new PrintWriter(socket.getOutputStream());
                        BufferedReader br=new BufferedReader(new InputStreamReader(socket.getInputStream()));
                       
                        //Send File List
                        String dirname="/media/VA/ACN/TextFiles";
                        File f1=new File(dirname);
                        File fl[]=f1.listFiles();
                       
                        //Sort Alphabetically
                        Arrays.sort(fl);
                       
                        //Counter for required files
                        int c=0;

                        for(int i=0;i<fl.length;i++)
                        {
                                if(fl[i].canRead() && (fl[i].toString()).endsWith(".txt"))
                                        c++;
                        }
                       
                        pw.println(" "+c+" .txt files found, listed A-Z.");

                        for(int i=0;i<fl.length;i++)
                              if((fl[i].toString()).endsWith(".txt"))       
                                        pw.println(" "+fl[i].getName()+" "+fl[i].length()+" Bytes");

                        //Output String Stream delimiter
                        pw.println("~");
                        pw.flush();
                       
                        //Convert ASCII to Decimal value.
                        String tem=br.readLine();                       
                        int temp=Integer.parseInt(tem);
                        temp-=49;
                        System.out.println("Index: "+temp);
                       
                        //Check if file exists
                        boolean flis=false;
                        int index=0;
                               
                        if(temp>=0 && temp<=fl.length)
                        {
                                flis=true;
                                index=temp;
                        }
                        else
                                flis=false;
                               
                        if(flis)
                        {
                                try
                                {
                                        //File Send Process, Independent
                                        File ff=new File(fl[index].getAbsolutePath());
                                        FileReader fr=new FileReader(ff);
                                        BufferedReader brf=new BufferedReader(fr);      
                                        String s;

                                        while((s=brf.readLine())!=null)
                                                pw.println(s);
                                        //Force write buffer to Client
                                        pw.flush();
                                       
                                        if(brf.readLine()==null)
                                                System.out.println("File Read Successful. Closing Socket.");                               
                                }
                                catch(IOException ioe)
                                {
                                        System.out.println("\nError in FTP. Please try again.");
                                }
                        }                       
                       
                        //Close streams and socket.
                        br.close();
                        socket.close();
                }
                catch(Exception E)
                {
                        System.out.println("\nConnection error, please try again.");
                }
        }
}

//client
import java.io.*;
import java.net.*;

class FileReceive
{
        public static void main(String args[])
        {
                try
                {
                        Socket socket=new Socket("127.0.0.1", 50000);
                       
                        //Read and Write on Socket.
                        PrintWriter out=new PrintWriter(socket.getOutputStream());
                        BufferedReader br=new BufferedReader(new InputStreamReader(socket.getInputStream()));
                       
                        //Read from Console
                        BufferedReader bu=new BufferedReader(new InputStreamReader(System.in));
                       
                        String s;
                       
                        while((br.read())!='~')
                                System.out.println(br.readLine());
                       
                        System.out.println("Enter file index no: ");
                        out.println(bu.read());
                        //Force write buffer
                        out.flush();
                       
                        //File Receive Process, Independent
                        try
                        {
                                BufferedWriter pw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("Received.txt")));
                               
                                while((s=br.readLine())!=null)
                                        pw.write(s);
                                //Force write buffer to Server
                                pw.close();
                               
                                if(br.readLine()==null)
                                        System.out.println("File Write Successful. Closing Socket.");
                        }
                        catch(IOException ioe)
                        {
                        }
                }
                catch(Exception E)
                {
                        System.out.println("Server is down, please try again later.");
                }
        }
}