java 150例子

import java.net.*; import java.io.*; import java.util.*; class FtpClient { static final boolean debug = false; public static final int FTP_PORT = 21; // ftp的端口 static int FTP_SUCCESS = 1; static int FTP_TRY_AGAIN = 2; static int FTP_ERROR = 3; // 数据传输套接字 private Socket dataSocket = null; private boolean replyPending = false; private boolean binaryMode = false; private boolean passiveMode = false; String user = null; // 登录用的用户名 String password = null; // 登录用的密码 String command; // 最近一次命令 int lastReplyCode; // 最近的响应信息 public String welcomeMsg; // 服务器的欢迎信息 // 从服务器返回的响应字符串对象 protected Vector serverResponse = new Vector(1); protected Socket serverSocket = null; // 与服务器通信的套接字 public PrintWriter serverOutput; public InputStream serverInput; // 从服务器读取响应的缓冲流 /** 返回服务器连接的状态 */ public boolean serverIsOpen() { return serverSocket != null; } /** 设置为被动模式 */ public void setPassive(boolean mode) { passiveMode = mode; } /** 读取服务器的响应信息 */ public int readServerResponse() throws IOException { StringBuffer replyBuf = new StringBuffer(32); int c; int continuingCode = -1; int code = -1; String response; if (debug) System.out.println("readServerResponse start"); try{ while (true) { if (debug) System.out.println("readServerResponse outer while loop: "+ serverInput.available()); while ((c = serverInput.read()) != -1) { if (c == '\r') { if ((c = serverInput.read()) != '\n') replyBuf.append('\r'); } replyBuf.append((char)c); if (c == '\n') break; } if (debug) System.out.println("Now past inner while loop"); response = replyBuf.toString(); replyBuf.setLength(0); if (debug) { System.out.print(response); } try { code = Integer.parseInt(response.substring(0, 3)); } catch (NumberFormatException e) { code = -1; } catch (StringIndexOutOfBoundsException e) { // 此行不存在响应码，循环跳到下一次 continue; } serverResponse.addElement(response); if (continuingCode != -1) { /* we've seen a XXX- sequence */ if (code != continuingCode || (response.length() >= 4 && response.charAt(3) == '-')) { continue; } else { continuingCode = -1; // 到达程序的结尾 break; } } else if (response.length() >= 4 && response.charAt(3) == '-') { continuingCode = code; continue; } else { break; } } }catch(Exception e){e.printStackTrace();} if (debug) System.out.println("readServerResponse done"); return lastReplyCode = code; } /** 发送命令 <i>cmd</i> 给服务器 */ public void sendServer(String cmd) { if (debug) System.out.println("sendServer start"); serverOutput.println(cmd); if (debug) System.out.println("sendServer done"); } /** 返回服务器的所有响应字符串 */ public String getResponseString() { String s = new String(); for(int i = 0;i < serverResponse.size();i++) { s+=serverResponse.elementAt(i); } serverResponse = new Vector(1); return s; } /** 获取响应字符串 */ public String getResponseStringNoReset() { String s = new String(); for(int i = 0;i < serverResponse.size();i++) { s+=serverResponse.elementAt(i); } return s; } /** 发送 QUIT 命令给服务器并关闭连接 */ public void closeServer() throws IOException { if (serverIsOpen()) { issueCommand("QUIT"); if (! serverIsOpen()) { return; } serverSocket.close(); serverSocket = null; serverInput = null; serverOutput = null; } } protected int issueCommand(String cmd) throws IOException { command = cmd; int reply; if (debug) System.out.println(cmd); if (replyPending) { if (debug) System.out.println("replyPending"); if (readReply() == FTP_ERROR) System.out.print("Error reading pending reply\n"); } replyPending = false; do { sendServer(cmd); reply = readReply(); if (debug) System.out.println("in while loop of issueCommand method"); } while (reply == FTP_TRY_AGAIN); return reply; } // 检测命令 protected void issueCommandCheck(String cmd) throws IOException { if (debug) System.out.println("issueCommandCheck"); if (issueCommand(cmd) != FTP_SUCCESS) { throw new FtpProtocolException(cmd); } } /** 读取返回数据 */ protected int readReply() throws IOException { lastReplyCode = readServerResponse(); switch (lastReplyCode / 100) { case 1: replyPending = true; case 2:// 这个case用来以后扩展功能 case 3: return FTP_SUCCESS; case 5: if (lastReplyCode == 530) { if (user == null) { throw new FtpLoginException("Not logged in"); } return FTP_ERROR; } if (lastReplyCode == 550) { if (!command.startsWith("PASS")) throw new FileNotFoundException(command); else throw new FtpLoginException("Error: Wrong Password!"); } } return FTP_ERROR; } //　打开数据连接 protected Socket openDataConnection(String cmd) throws IOException { ServerSocket portSocket = null; String portCmd; InetAddress myAddress = InetAddress.getLocalHost(); byte addr[] = myAddress.getAddress(); int shift; String ipaddress; int port = 0; IOException e; if (this.passiveMode) { // 首先尝试被动模式传输 try { getResponseString(); if (issueCommand("PASV") == FTP_ERROR) { e = new FtpProtocolException("PASV"); throw e; } String reply = getResponseStringNoReset(); reply = reply.substring(reply.lastIndexOf("(") + 1, reply .lastIndexOf(")")); StringTokenizer st = new StringTokenizer(reply, ","); String[] nums = new String[6]; int i = 0; while (st.hasMoreElements()) { try { nums[i] = st.nextToken(); i++; } catch (Exception a) { a.printStackTrace(); } } ipaddress = nums[0] + "." + nums[1] + "." + nums[2] + "." + nums[3]; try { int firstbits = Integer.parseInt(nums[4]) << 8; int lastbits = Integer.parseInt(nums[5]); port = firstbits + lastbits; } catch (Exception b) { b.printStackTrace(); } if ((ipaddress != null) && (port != 0)) { dataSocket = new Socket(ipaddress, port); } else { e = new FtpProtocolException("PASV"); throw e; } if (issueCommand(cmd) == FTP_ERROR) { e = new FtpProtocolException(cmd); throw e; } } catch (FtpProtocolException fpe) { portCmd = "PORT "; // 附加host地址 for (int i = 0; i < addr.length; i++) { portCmd = portCmd + (addr[i] & 0xFF) + ","; } try { portSocket = new ServerSocket(20000); // 附加端口 portCmd = portCmd + ((portSocket.getLocalPort() >>> 8) & 0xff) + "," + (portSocket.getLocalPort()