FTP Client

[Jeff Holmes]

Carl asked that I post some source code for an FTP Client that he helped me with. This is just real rough source, but it provides some very basic functionality and can be improved on and implemented into almost anything you want. Thanks for the help Carl

<font size=2>
import java.io.*;
import java.net.*;
import java.util.*;
import javax.swing.*;
  
public class FTPClient {
private boolean pauser = false;  //Used for wait return
private static final int CNTRL_PORT = 21;
private Socket csock = null;
private Socket dsock = null;
private BufferedReader dcis;
private PrintWriter pos;

    public FTPClient(String server, String user, String pass) {
        try { 
            ftpConnect(server);
            ftpLogin(user, pass);
        } catch(IOException ioe) {
System.err.println("Failed with connection to Server");
}
    }

private String responseParser(String resp) throws IOException {
if (resp.substring(0,1).equals("1")) {
pauser = true;
return(resp);
} else if (resp.substring(0,1).equals("2")) {
pauser = false;
return(resp);
} else if ((resp.substring(0,1).equals("3"))
  | | (resp.substring(0,1).equals("4"))
  | | (resp.substring(0,1).equals("5"))) {
return(resp);
} else {
return(null);
}
}

public void ftpLogout() {
try {
pos.print("BYE\r\n");
pos.flush();
pos.close();
dcis.close();
csock.close();
dsock.close();
} catch (IOException e) {
System.err.println("Error closing FTP: " + e.getMessage());
}
}

private String ftpSendCmd(String cmd) throws IOException {
if (pauser) {
if (dcis != null) {
String discard = dcis.readLine();
pauser = false;
}
}
pos.print(cmd + "\r\n");
pos.flush();
String response = responseHandler(cmd);
return(response);
}

private String responseHandler(String cmd) throws IOException {
String reply = this.responseParser(dcis.readLine());
String numerals = reply.substring(0,3);
String hyph_test = reply.substring(3,4);
String next = null;
        if(hyph_test.equals("-")) {
            String tester = numerals + " ";
            boolean done = false;
            while(!done) { 
            next = dcis.readLine();
                while (next.equals("") | | next.equals("  ")) {
                    next = dcis.readLine();
            }
            if(next.substring(0,4).equals(tester))
            done = true;
}
        return next;
        } else 
return reply;
}

    private Socket ftpGetDataSock() throws IOException {
        String reply = ftpSendCmd("PASV");
        StringTokenizer st = new StringTokenizer(reply, ",");
        String[] parts = new String[6]; 
        int i = 0; 
        while(st.hasMoreElements()) {
            try {
                parts[ i ] = st.nextToken();
                i++;
            } catch(NoSuchElementException nope){nope.printStackTrace();}
        } 
        String[] possNum = new String[3];
        for(int j = 0; j < 3; j++) {
            possNum[j] = parts[0].substring(parts[0].length() - (j + 1),
                parts[0].length() - j);
            if(!Character.isDigit(possNum[j].charAt(0)))
                possNum[j] = "";
        }
        parts[0] = possNum[2] + possNum[1] + possNum[0];
        String[] porties = new String[3];
        for(int k = 0; k < 3; k++) {
            if((k + 1) <= parts[5].length())
                porties[k] = parts[5].substring(k, k + 1);
            else porties[k] = "FOOBAR"; 
            if(!Character.isDigit(porties[k].charAt(0)))
                    porties[k] = "";
        } 
        parts[5] = porties[0] + porties[1] + porties[2];
        String ip = parts[0]+"."+parts[1]+"."+parts[2]+"."+parts[3];
        int port = -1;
        try { 
            int big = Integer.parseInt(parts[4]) << 8;
            int small = Integer.parseInt(parts[5]);
            port = big + small; 
        } catch(NumberFormatException nfe) {nfe.printStackTrace();}
        if((ip != null) && (port != -1))
  
            dsock = new Socket(ip, port);
        else throw new IOException();
        return dsock;
    }

    public void ftpSetTransferType(boolean asc) throws IOException {
        String ftype = (asc? "A" : "I");
        ftpSendCmd("TYPE "+ftype);
    }   

    private void ftpConnect(String server) throws IOException {
        csock = new Socket(server, CNTRL_PORT);
        InputStream cis = csock.getInputStream();
        dcis =  new BufferedReader(new InputStreamReader(cis));
        OutputStream cos = csock.getOutputStream();
        pos = new PrintWriter(cos, true);
        String numerals = responseHandler(null); 
        if(numerals.substring(0,3).equals("220")) ; 
        else System.err.println("Error connecting to ftp server.");
    }
  
    private void ftpLogin(String user, String pass)
        throws IOException {
        ftpSendCmd("USER "+user);
        ftpSendCmd("PASS "+pass);
    }
  
    private void ftpSetDir(String dir)
        throws IOException { 
        ftpSendCmd("CWD "+dir);
    }

    private String getAsString(InputStream is) {
    int c=0;
        char lineBuffer[]=new char[128], buf[]=lineBuffer;
        int room= buf.length, offset=0;
        try {
        loop:
while (true) {
            switch (c = is.read() ) {
                case -1: 
break loop;
                default: 
if (--room < 0) {
                    buf = new char[offset + 128];
                    room = buf.length - offset - 1;
                    System.arraycopy(lineBuffer, 0,buf, 0, offset);
                    lineBuffer = buf;
                    }
                    buf[offset++] = (char) c;
                    break;
                }
            }
        } catch(IOException ioe) {
System.err.println("Error in getAsStrig." + ioe.getMessage());
//ioe.printStackTrace();
}
        if ((c == -1) && (offset == 0)) {
            return null;
        }
        return String.copyValueOf(buf, 0, offset);
    }

    public String download(String dir, String file) throws IOException { 
return download(dir, file, true); 
}
  
    public String download(String dir, String file, boolean asc) throws IOException {
        ftpSetDir(dir);
        ftpSetTransferType(asc);
        dsock = ftpGetDataSock();
        InputStream is = dsock.getInputStream();
        ftpSendCmd("RETR "+file);
        String contents = getAsString(is);
        ftpLogout();
        return contents;
    }
  
    public void append(String dir, String file, String what, boolean asc) throws IOException {
        ftpSetDir(dir);
        ftpSetTransferType(asc);
        dsock = ftpGetDataSock();
        OutputStream os = dsock.getOutputStream();
        DataOutputStream dos = new DataOutputStream(os);
        ftpSendCmd("APPE "+file); 
        dos.writeBytes(what);
        dos.flush();
        dos.close();
        ftpLogout();
    }
  
    public void upload(String remotedir, String file, String localdir, boolean asc, JProgressBar progbar) throws IOException {
//Check if file is OK
int inc = 0;
progbar.setMinimum(0);
progbar.setValue(0);
progbar.update(progbar.getGraphics());
File ftpFile = new File(localdir + "\\" + file);
if (!ftpFile.isFile()) {
throw new IOException("FTP file does not exist."); 
}
RandomAccessFile raf = new RandomAccessFile(ftpFile,"r");
progbar.setMaximum(((int)raf.length()));
        ftpSetDir(remotedir);
        ftpSetTransferType(asc);
        dsock = ftpGetDataSock();
        OutputStream os = dsock.getOutputStream();
        DataOutputStream dos = new DataOutputStream(os);
        ftpSendCmd("STOR "+file);
int idata = 0;
while (true) {
idata = raf.read();
if (idata != -1) {
dos.writeByte(idata);
} else {
break;
}
if (progbar!=null) {
++inc;
if (inc > 20) {
progbar.setValue(progbar.getValue() + 20);
progbar.update(progbar.getGraphics());
inc = 0;
}
}
}
        dos.flush();
        dos.close();
    }
    
    public String delete(String dir, String File) throws IOException {
        ftpSetDir(dir);
        return(ftpSendCmd("DELE "+ File));      
    }
  
public String getList(String dir) throws IOException {
   ftpSetDir(dir);
   ftpSetTransferType(true);
   dsock = ftpGetDataSock();
   InputStream is = dsock.getInputStream();
   ftpSendCmd("LIST");
   String contents = getAsString(is);
   return contents;
}

public String getNlst(String dir) throws IOException {
ftpSetDir(dir);
ftpSetTransferType(true);
dsock = ftpGetDataSock();   
InputStream is = dsock.getInputStream();   
ftpSendCmd("NLST");   
String contents = getAsString(is);   
return contents;
}
}

Added UBB CODE tags to preserver your indentation
[This message has been edited by Frank Carver (edited November 14, 2000).]
[This message has been edited by Carl Trusiak (edited November 15, 2000).]
[This message has been edited by shailesh sonavadekar (edited October 25, 2001).]

[Carl Trusiak]

Thank You Jeff, nice work.

[George Brown]

good stuff, but I wondered why half of it is italicised and half isn't... ?

[Carl Trusiak]

I edited the code, UBB was interpreting the [ i ] as Italic. Had to put spaces in it to prevent that.

[gautham kasinath]

hey! is der anyway one can increase the font size on the

tags???
Regds
Gautham Kasinath

[shailesh sonavadekar]

i hope this is legible for all. Gautam , I hope this will be helpful.
Shailesh.