JSch是Java Secure Channel的缩写。JSch是一个SSH2的纯Java实现。它允许你连接到一个SSH服务器，并且可以使用端口转发，X11转发，文件传输等，当然你也可以集成它的功能到你自己的应用程序。

  本文只介绍如何使用JSch实现的SFTP功能。

  SFTP是Secure File Transfer Protocol的缩写，安全文件传送协议。可以为传输文件提供一种安全的加密方法。SFTP 为 SSH的一部份，是一种传输文件到服务器的安全方式。SFTP是使用加密传输认证信息和传输的数据，所以，使用SFTP是非常安全的。但是，由于这种传输方式使用了加密/解密技术，所以传输效率比普通的FTP要低得多，如果您对网络安全性要求更高时，可以使用SFTP代替FTP。（来自百度的解释） 

  要使用JSch，需要下载它的jar包，请从官网下载它：http://www.jcraft.com/jsch/

package com.ebao.jewel.gs.integration.pub.connection.impl;     import java.io.FileNotFoundException;  import java.io.OutputStream;  import java.net.UnknownHostException;  import java.util.Properties;  import java.util.Vector;     import org.apache.commons.httpclient.auth.AuthenticationException;     import com.ebao.jewel.gs.integration.pub.CommonLog.exception.ExceptionUtil;  import com.ebao.jewel.gs.integration.pub.CommonLog.utils.JewelIntLogUtils;  import com.ebao.jewel.gs.integration.pub.commons.InterfaceUtil;  import com.ebao.jewel.gs.integration.pub.connection.IConnection;  import com.ebao.jewel.gs.integration.pub.constants.InterfaceConstants;  import com.jcraft.jsch.ChannelSftp;  import com.jcraft.jsch.JSch;  import com.jcraft.jsch.JSchException;  import com.jcraft.jsch.Session;     public class JewelSftpClient implements IConnection {       private Session sshSession = null;       private ChannelSftp channelSftp = null;       private int connectTimes = 0;       public boolean connect(String host, int port, String username, String pwd)       throws Exception {      if (sshSession == null || !sshSession.isConnected()) {           JSch jsch = new JSch();           try {          sshSession = jsch.getSession(username, host, port);        } catch (JSchException je) {          // throw new Connection          throw je;        }      }      if (!sshSession.isConnected()) {        InterfaceUtil.batchLog("[TEST] sshSession.connect()");        sshSession.setPassword(pwd);           Properties sshConfig = new Properties();        sshConfig.put("StrictHostKeyChecking", "no");        sshSession.setConfig(sshConfig);        try {          sshSession.connect();        } catch (JSchException ex) {             if (ex.getMessage().indexOf("Session.connect") != -1) {            throw new UnknownHostException(ExceptionUtil.getExceptionMsg(ex));          } else {            throw new AuthenticationException(ExceptionUtil.getExceptionMsg(ex));          }        }      }      InterfaceUtil.batchLog("[TEST] sshSession has connected.");      try {        if (channelSftp == null || !channelSftp.isConnected()) {          InterfaceUtil.batchLog("[TEST] channelSftp.connect()");          channelSftp = (ChannelSftp) sshSession.openChannel("sftp");          channelSftp.connect();        }           InterfaceUtil.batchLog("[TEST] channelSftp has been established.");        return true;      } catch (JSchException je) {        if (connectTimes++ < InterfaceConstants.MAX_CONNECT_TIMES) {          String seq = connectTimes == 1 ? "1st" : connectTimes == 2              ? "2nd"              : connectTimes == 3 ? "3rd" : connectTimes + "st";          InterfaceUtil.batchLog("[TEST]" + seq              + " connection failed. Disconnected "              + (disconnect() == true ? "succeeded" : "failed"));          long sleepTime = InterfaceUtil.getConnectSleepTime() * 1000L;          Thread.sleep(sleepTime);          InterfaceUtil.batchLog("[TEST]" + sleepTime + " ms passed. Try "              + (int) (connectTimes + 1) + " connection.");          if (connectTimes == 4) {            InterfaceUtil                .batchLog("[TEST] !!!!!!!!!!!connection goes wrong!!!!!!!!!!!!!!!!");          }          return connect(host, port, username, pwd);        } else {          InterfaceUtil.batchLog("[TEST] connect excceeded 10 times.");          throw je;        }      }    }       public boolean disconnect() throws Exception {      try {        if (channelSftp != null && channelSftp.isConnected()) {             channelSftp.disconnect();          InterfaceUtil.batchLog("[TEST] channelSftp has cloesd.");        }        if (sshSession != null && sshSession.isConnected()) {             sshSession.disconnect();          InterfaceUtil.batchLog("[TEST] sshSession has cloesd.");        }        return true;      } catch (Exception e) {        return false;         }       }       public void upload(String src, String dst) throws Exception {      channelSftp.put(src, dst);    }       public void download(String src, String dst) throws Exception {      channelSftp.get(src, dst);       }       @SuppressWarnings("unchecked")    public Vector<Object> listFiles(String directory) throws Exception {      try {        channelSftp.cd(directory);      } catch (Exception e) {        throw new FileNotFoundException("No such file or directory.src:"            + directory);      }      Vector<Object> files = channelSftp.lsnames(directory);      return files;       }       public boolean moveFile(String src, String dst) throws Exception {      try {        channelSftp.rename(src, dst);        return true;      } catch (Exception e) {        JewelIntLogUtils.batchLog("[TEST] Move the file from " + src + " to "            + dst + " fail", e);        throw e;      }    }       public boolean isConnected() {      return channelSftp != null && channelSftp.isConnected();    }       @Override    public void download(String src, OutputStream out) throws Exception {      channelSftp.get(src, out);    }  }