import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPFile;
import org.apache.commons.net.ftp.FTPReply;public class FtpCtrl {public static void main(String[] args) throws Exception {String url = "ip";int port = 21;String username = "username";String password = "password";String path = "/";String filename = "ftp.test.tmp";FileInputStream fis = new FileInputStream("/home/iamsuperman/ftp.txt");uploadFile(url, port, username, password, path, filename, fis);}/*** @param ip*            FTP服务器IP地址* @param port*            FTP服务器端口* @param username*            FTP服务器登录名* @param password*            FTP服务器密码* @param remotePath*            远程文件路径* @param fileName*            待删除的文件名* @return* @see [类、类#方法、类#成员]*/public static boolean deleteFtpFile(String ip, int port, String username, String password, String remotePath,String fileName) {boolean success = false;FTPClient ftp = new FTPClient();try {int reply;// 连接FTP服务器if (port > -1) {ftp.connect(ip, port);} else {ftp.connect(ip);}// 登录
            ftp.login(username, password);reply = ftp.getReplyCode();if (!FTPReply.isPositiveCompletion(reply)) {ftp.disconnect();return success;}// 转移到FTP服务器目录
            ftp.changeWorkingDirectory(remotePath);success = ftp.deleteFile(remotePath + "/" + fileName);ftp.logout();} catch (IOException e) {e.printStackTrace();success = false;} finally {if (ftp.isConnected()) {try {ftp.disconnect();} catch (IOException e) {e.printStackTrace();}}}return success;}/*** Description: 从FTP服务器下载文件* * @param ip*            FTP服务器hostname* @param port*            FTP服务器端口* @param username*            FTP登录账号* @param password*            FTP登录密码* @param remotePath*            FTP服务器上的相对路径* @param fileName*            要下载的文件名* @param localPath*            下载后保存到本地的路径* @return*/public static boolean downloadFile(String ip, int port, String username, String password, String remotePath,String fileName, String localPath) {boolean success = false;FTPClient ftp = new FTPClient();try {int reply;// 连接FTP服务器if (port > -1) {ftp.connect(ip, port);} else {ftp.connect(ip);}ftp.login(username, password);// 登录reply = ftp.getReplyCode();if (!FTPReply.isPositiveCompletion(reply)) {ftp.disconnect();return success;}ftp.changeWorkingDirectory(remotePath);// 转移到FTP服务器目录FTPFile[] fs = ftp.listFiles();for (FTPFile ff : fs) {if (ff.getName().equals(fileName)) {File localFile = new File(localPath + "/" + ff.getName());OutputStream is = new FileOutputStream(localFile);ftp.retrieveFile(ff.getName(), is);is.close();}}ftp.logout();success = true;} catch (IOException e) {e.printStackTrace();} finally {if (ftp.isConnected()) {try {ftp.disconnect();} catch (IOException e) {e.printStackTrace();}}}return success;}/*** Description: 向FTP服务器上传文件* * @param ip*            FTP服务器hostname* @param port*            FTP服务器端口，如果默认端口请写-1* @param username*            FTP登录账号* @param password*            FTP登录密码* @param path*            FTP服务器保存目录* @param filename*            上传到FTP服务器上的文件名* @param input*            输入流* @return 成功返回true，否则返回false*/public static boolean uploadFile(String ip, int port, String username, String password, String path,String filename, InputStream input) {boolean success = false;FTPClient ftp = new FTPClient();try {int reply;// 连接FTP服务器if (port > -1) {ftp.connect(ip, port);} else {ftp.connect(ip);}// 登录FTP
            ftp.login(username, password);reply = ftp.getReplyCode();if (!FTPReply.isPositiveCompletion(reply)) {ftp.disconnect();return success;}ftp.changeWorkingDirectory(path);ftp.storeFile(filename, input);input.close();ftp.logout();success = true;} catch (IOException e) {success = false;e.printStackTrace();} finally {if (ftp.isConnected()) {try {ftp.disconnect();} catch (IOException e) {e.printStackTrace();}}}return success;}}
==============================================================================获取连接时候：ftp.enterLocalPassiveMode();这句话特别重要。