用java编写多线程ftp断点下载文件程序

前几天看到有某位网友写了用http进行断点下载文件，但是网上没有看到ftp断点下载的文章或代码，现在本人写了一下。经过测试没有问题。请大家多多指教。如有疏漏的地方请各位技术友人指出。本人不胜感激。

 

 

package test.download; 

import java.io.File;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.RandomAccessFile;

import java.net.SocketException;

import java.util.concurrent.CountDownLatch;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

 

import org.apache.commons.net.ftp.FTPClient;

import org.apache.commons.net.ftp.FTPClientConfig;

import org.apache.commons.net.ftp.FTPFile;

import org.apache.commons.net.ftp.FTPReply;

import org.apache.log4j.Logger;

import util.LogMgr; 

publicclass TestProtocolFtp {

 

   private FTPClientFTP;

   private Stringhost;

   privateintport;

   private Stringuser;

   private Stringpwd;

   private Stringtaskdate;

   privatebooleanforceexit;

   privatestatic Loggerlog =LogMgr.getInstance().getSystemLogger();

   public String toString() {

      returnhost +":" +port +"@" +user +"/" +pwd;

   }

   publicboolean Login(String strHost,int nPort, String strUser,

          StringstrPwd) {

      host = strHost;

      port = nPort;

      user = strUser;

      pwd = strPwd;

      boolean bOK =false;

      try {

          if (FTP ==null) {

             FTP =new FTPClient();

          }else {

             try {

                 FTP.disconnect();

             }catch (Exception e) {

             }

          }

          log.debug("登录用户:" + strUser + "   密码:" + strPwd);

          FTP.setDefaultTimeout(3600 * 1000);

          FTP.setConnectTimeout(3600 * 1000);

          FTP.connect(strHost, nPort);

 

          int reply =FTP.getReplyCode();

          if (!FTPReply.isPositiveCompletion(reply)){

             FTP.disconnect();

             log.error("FTPserver refused connection.");

             returnfalse;

          }

 

          bOK=FTP.login(strUser, strPwd);

          if (bOK) {

             FTP.enterLocalPassiveMode();

             FTP.setFileType(FTPClient.BINARY_FILE_TYPE);//设置为二进制传输模式

             FTP.setDataTimeout(3600 * 1000);

          }else {

             log

                    .error("FTP server Login Failure Code:"

                           +FTP.getReplyCode());

          }

      }catch (SocketException se) {

          log.error("FTPlogin", se);

      }catch (Exception e) {

          log.error("FTPlogin", e);

      }

 

      return bOK;

   }

 

   publicvoid Close() {

      try {

          if (FTP !=null) {

             FTP.logout();

             FTP.disconnect();

          }

      }catch (Exception e) {

      }

   }

 

   privateboolean ftpValidate() {

      if ((FTP !=null)&& (FTP.isConnected()))

          returntrue;

      else

          returnfalse;

   }

 

   publicboolean ReLogin() {

      int i = 1;

      boolean ret =false;

 

      if (ftpValidate()) {

          returntrue;

      }

 

      while (!ftpValidate()) {

          if (i > 3) {

             return ret;

          }

 

          log.debug(":第" + i + "次ReLogin登陆ftp:" + host +"," +user);

 

          try {

             Thread.sleep(1000* i * 30);

          }catch (Exception e) {

             log.error(":ftp relogin failed. ", e);

          }

 

          ret= Login(host,port,user,pwd);

          if (ret)

             break;

 

          i++;

      }

 

      return ret;

   }

 

   class MonitorThreadextends Thread {

      FTPClientftpClient =null;

      intnSeconds = 0;

      ThreadftpThread =null;

 

      public MonitorThread(int nSeconds, FTPClient ftp, Thread t) {

          ftpClient = ftp;

          this.nSeconds = nSeconds;

          this.ftpThread = t;

      }

      publicvoid run() {

          if (nSeconds > 0) {

             try {

                 log.debug(":sleep开始");

                 Thread.sleep(((long)nSeconds) * 1000);

                 log.debug(":sleep结束");

             }catch (InterruptedException e){

                 log.debug(":Monitor thread interrupted by ftp thread");

                 return;

             }

             try {

                 log.debug("ftp timeout for " +nSeconds

                        +" seconds, interrupt ftp thread");

 

                 ftpThread.interrupt();

             }catch (Exception e) {

                 log.error("Interruptftp error", e);

             }

          }

      }

   }

 

   privatelongcontentLength = 0;

 

   /**从服务器下载指定的文件到本地，返回本地文件名称，如果返回为