[HELP] Download file from FTP server

Question

hi,
I want to write a java program that can download and upload files from ftp server. Currently I only manage to upload a file to ftp server but i cant download file from ftp server. Here is the source code that only allow user to upload file. Anyone can give me some guidelines so that my program can download and also upload file? thx.
import java.io.*;
import java.net.*;
public class FTPUpload {
private static final int CTRLPORT = 21;
private static Socket ctrlSocket;
private static PrintWriter ctrlOutput;
private static BufferedReader ctrlInput;
private static byte[] localHostAddress;
public final static String DIR = "C:\\zip\\";
public static void main(String[] args) {
try {
String host = "192.168.1.1";
String loginName = "testuser";
String password = "password";
String dirName = "/home/testuser";
String fileName = "hello.zip";
ctrlSocket = new Socket(host, CTRLPORT);
localHostAddress = ctrlSocket.getLocalAddress().getAddress();
ctrlOutput = new PrintWriter(ctrlSocket.getOutputStream());
ctrlInput = new BufferedReader(new InputStreamReader(ctrlSocket.getInputStream()));
ctrlOutput.println("USER " + loginName);
ctrlOutput.flush();
ctrlOutput.println("PASS " + password);
ctrlOutput.flush();
ctrlOutput.println("CWD " + dirName);
ctrlOutput.flush();
ctrlOutput.println("TYPE I");
ctrlOutput.flush();
FileInputStream fis = new FileInputStream(DIR + fileName);
Socket dataSocket = dataConnection("STOR " + fileName);
OutputStream outstr = dataSocket.getOutputStream();
int n;
byte[] buff = new byte[1024];
while ((n = fis.read(buff)) > 0) {
outstr.write(buff,0,n);
dataSocket.close();
fis.close();
ctrlOutput.close();
ctrlInput.close();
ctrlSocket.close();
}catch (Exception e) {
e.printStackTrace();
private static Socket dataConnection(String ctrlcmd)
throws IOException,UnknownHostException {
String cmd = "PORT ";
ServerSocket serverDataSocket = new ServerSocket(0,1);
for (int i=0;i<4;i++) {
cmd = cmd + (localHostAddress[i] & 0xff) + ",";
cmd = cmd + (((serverDataSocket.getLocalPort())/256) & 0xff)
+ ","
+ (serverDataSocket.getLocalPort() & 0xff);
ctrlOutput.println(cmd);
ctrlOutput.flush();
ctrlOutput.println(ctrlcmd);
ctrlOutput.flush();
Socket dataSocket = serverDataSocket.accept();
serverDataSocket.close();
return dataSocket;
}

Answer 1

Or just use a java.net.URL("ftp://...) ..., get its input stream, and away you go ...