使用的是 Apache 的 commons-net 实现的。

import java.io.File;
import java.io.FileInputStream;
import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPReply;

/**
 * FTP 连接，上传
 * @author lc
 * @web www.liuchang.org
 * 2015-10-29
 */
public class FTPUtil {
	
	public static String SUCCESS = "S";
	public static String ERROR = "E";
	
	private FTPClient ftp = null;
	
	/**
	 * 建立连接
	 * @param url
	 * @param port
	 * @param username
	 * @param password
	 */
	public void connect(String url, int port, String username, 
			String password){
		
		ftp = new FTPClient();
		try {
			ftp.connect(url, port);
			ftp.login(username, password);
			int reply = ftp.getReplyCode();
			if (!FTPReply.isPositiveCompletion(reply)) { 
	            ftp.disconnect(); 
	            throw new RuntimeException("FTP connect error, ReplyCode :" + reply);
	        }
			
		} catch (Exception e) {
			disconnect();
			e.printStackTrace();
		}
		
	}
	
	/**
	 * 文件上传
	 * @param directory 上传目录
	 * @param uploadFile 本地文件目录
	 * @param saveFileName 文件名
	 * @return
	 */
	public String uploadFile(String directory, String uploadFile, String saveFileName){
		if(ftp == null){
			System.out.println("create connect before upload file");
			return ERROR;
		}
		
		try {
			ftp.changeWorkingDirectory(directory);
			ftp.storeFile(saveFileName, new FileInputStream(new File(uploadFile)));
		} catch (Exception e) {
			disconnect();
			e.printStackTrace();
			return ERROR;
		}
		
		return SUCCESS;
	}
	
	public void disconnect(){
		if(ftp != null){
			try {
				ftp.logout();
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
	}
}