FTP协议Java实现

Java代码:
FTPClient.java

package org;

import java.io.BufferedInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.Writer;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;

public class FtpClient ...{

public static final int DEFAULT_PORT = 1968;

private static int print(Reader in) throws IOException ...{
int c;
int prev = 0, current = 0;
int result = 0;
int count = 0, k1 = 0, k2 = 0, k3 = 0;
while (prev != ' ' && current != ' ') ...{
prev = current;
c = in.read();
current = c;
if (count < 3) ...{
switch (count) ...{
case 0:
k1 = current - '0';
break;
case 1:
k2 = current - '0';
break;
case 2:
k3 = current - '0';
break;
}
}
count++;
System.out.write(current);
}
result = k1 * 100 + k2 * 10 + k3;
return result;
}

private static void printData(Reader in) throws IOException ...{
int c = 0;

while ((c = in.read()) != -1) ...{
System.out.print((char) c);
}
System.out.println();
}

private static void inputCommand(Writer out, String command) throws IOException ...{
out.write(command);
out.write(" \r\n");
out.flush();
}

public static void main(String[] args) ...{
String hostname = "192.168.1.101";

Socket commandConn = null;

Socket dataConn = null;

try ...{

commandConn = new Socket(hostname, DEFAULT_PORT);

Writer out = new OutputStreamWriter(commandConn.getOutputStream(),
"8859_1");

InputStream raw = commandConn.getInputStream();
BufferedInputStream buffer = new BufferedInputStream(raw);
InputStreamReader commandIn = new InputStreamReader(buffer,
"8859_1");

System.out.println("login in");
int i = print(commandIn);// 220

inputCommand(out, "USER winters");
System.out.println("USER winters");
i = print(commandIn);// 331

inputCommand(out, "PASS 123456");
System.out.println("PASS 123456");
i = print(commandIn);// 230

inputCommand(out, "SYST");
System.out.println("SYST");
i = print(commandIn);// 215

inputCommand(out, "PWD");
System.out.println("PWD");
i = print(commandIn);// 257

inputCommand(out, "TYPE A");
System.out.println("TYPE A");
i = print(commandIn);// 200

inputCommand(out, "PASV");
System.out.println("PASV");

int port = getPortNumber(commandIn);
dataConn = new Socket(hostname, port);
BufferedInputStream dataBuffer = new BufferedInputStream(dataConn
.getInputStream());
InputStreamReader dataIn = new InputStreamReader(dataBuffer,
"8859_1");

System.out.println("Connected " + hostname + " on " + port);

/** *//**
* LIST
*/

inputCommand(out, "LIST");
System.out.println("LIST");
System.out.print("commandIn : ");
i = print(commandIn);// 150

System.out.print("dataIn : ");
printData(dataIn);// abc

i = print(commandIn);// 226

/** *//** ************************************* */

inputCommand(out, "PASV");
System.out.println("PASV");
port = getPortNumber(commandIn);

dataConn = new Socket(hostname, port);
dataBuffer = new BufferedInputStream(dataConn.getInputStream());
dataIn = new InputStreamReader(dataBuffer, "8859_1");

System.out.println("Connected " + hostname + " on " + port);

/** *//**
* RETR
*/

inputCommand(out, "RETR 1.txt");
System.out.println("RETR 1.txt");

System.out.print("commandIn : ");
i = print(commandIn);// 150

System.out.print("dataIn : ");
printData(dataIn);// abc

i = print(commandIn);// 226

} catch (IOException e) ...{
System.err.println(e);
} finally ...{
try ...{
if (commandConn != null)
commandConn.close();
if (dataConn != null)
dataConn.close();
} catch (IOException e) ...{
System.err.println(e);
}
}

}

private static int getPortNumber(InputStreamReader in) throws IOException ...{
int c;
int prev = 0, current = 0;
boolean start = false;
ByteArrayOutputStream out = new ByteArrayOutputStream();
while (prev != ' ' && current != ' ') ...{
prev = current;
c = in.read();
current = c;

if (prev == '(')
start = true;
if (current == ')')
start = false;
if (start)
out.write(current);
// System.out.println("==" + out.toString() + "==");
System.out.write(current);
}

String ipWithPort = out.toString();
StringTokenizer stk = new StringTokenizer(ipWithPort, ",");
List list = new ArrayList();
while (stk.hasMoreTokens()) ...{
list.add(stk.nextToken());
}
String[] str = (String[]) list.toArray(new String[list.size()]);
int a = Integer.parseInt(str[4]);
int b = Integer.parseInt(str[5]);
int port = a * 256 + b;
// System.out.println("debug: port == " + port);
return port;
}
}