java使用Apache工具集实现ftp文件传输代码详解

<dependency>
  <groupId>commons-net</groupId>
  <artifactId>commons-net</artifactId>
  <version>3.5</version>
</dependency>

/**
   * 连接FTP Server
   * @throws IOException
   */
public static final String ANONYMOUS_USER="anonymous";
private FTPClient connect(){
	FTPClient client = new FTPClient();
	try{
		//连接FTP Server
		client.connect(this.host, this.port);
		//登陆
		if(this.user==null||"".equals(this.user)){
			//使用匿名登陆
			client.login(ANONYMOUS_USER, ANONYMOUS_USER);
		} else{
			client.login(this.user, this.password);
		}
		//设置文件格式
		client.setFileType(FTPClient.BINARY_FILE_TYPE);
		//获取FTP Server 应答
		int reply = client.getReplyCode();
		if(!FTPReply.isPositiveCompletion(reply)){
			client.disconnect();
			return null;
		}
		//切换工作目录
		changeWorkingDirectory(client);
		System.out.println("===连接到FTP："+host+":"+port);
	}
	catch(IOException e){
		return null;
	}
	return client;
}
/**
   * 切换工作目录，远程目录不存在时，创建目录
   * @param client
   * @throws IOException
   */
private void changeWorkingDirectory(FTPClient client) throws IOException{
	if(this.ftpPath!=null&&!"".equals(this.ftpPath)){
		Boolean ok = client.changeWorkingDirectory(this.ftpPath);
		if(!ok){
			//ftpPath 不存在，手动创建目录
			StringTokenizer token = new StringTokenizer(this.ftpPath,"\\//");
			while(token.hasMoreTokens()){
				String path = token.nextToken();
				client.makeDirectory(path);
				client.changeWorkingDirectory(path);
			}
		}
	}
}
/**
   * 断开FTP连接
   * @param ftpClient
   * @throws IOException
   */
public void close(FTPClient ftpClient) throws IOException{
	if(ftpClient!=null && ftpClient.isConnected()){
		ftpClient.logout();
		ftpClient.disconnect();
	}
	System.out.println("!!!断开FTP连接："+host+":"+port);
}

/**
   * 上传文件
   * @param targetName 上传到ftp文件名
   * @param localFile 本地文件路径
   * @return
   */
public Boolean upload(String targetName,String localFile){
	//连接ftp server
	FTPClient ftpClient = connect();
	if(ftpClient==null){
		System.out.println("连接FTP服务器["+host+":"+port+"]失败！");
		return false;
	}
	File file = new File(localFile);
	//设置上传后文件名
	if(targetName==null||"".equals(targetName))
	      targetName = file.getName();
	FileInputStream fis = null;
	try{
		long now = System.currentTimeMillis();
		//开始上传文件
		fis = new FileInputStream(file);
		System.out.println(">>>开始上传文件："+file.getName());
		Boolean ok = ftpClient.storeFile(targetName, fis);
		if(ok){
			//上传成功
			long times = System.currentTimeMillis() - now;
			System.out.println(String.format(">>>上传成功：大小：%s,上传时间：%d秒", formatSize(file.length()),times/1000));
		} else//上传失败
		System.out.println(String.format(">>>上传失败：大小：%s", formatSize(file.length())));
	}
	catch(IOException e){
		System.err.println(String.format(">>>上传失败：大小：%s", formatSize(file.length())));
		e.printStackTrace();
		return false;
	}
	finally{
		try{
			if(fis!=null)
			          fis.close();
			close(ftpClient);
		}
		catch(Exception e){
		}
	}
	return true;
}

/**
   * 下载文件
   * @param localPath 本地存放路径
   * @return
   */
public int download(String localPath){
	// 连接ftp server
	FTPClient ftpClient = connect();
	if(ftpClient==null){
		System.out.println("连接FTP服务器["+host+":"+port+"]失败！");
		return 0;
	}
	File dir = new File(localPath);
	if(!dir.exists())
	      dir.mkdirs();
	FTPFile[] ftpFiles = null;
	try{
		ftpFiles = ftpClient.listFiles();
		if(ftpFiles==null||ftpFiles.length==0)
		        return 0;
	}
	catch(IOException e){
		return 0;
	}
	int c = 0;
	for (int i=0;i<ftpFiles.length;i++){
		FileOutputStream fos = null;
		try{
			String name = ftpFiles[i].getName();
			fos = new FileOutputStream(new File(dir.getAbsolutePath()+File.separator+name));
			System.out.println("<<<开始下载文件："+name);
			long now = System.currentTimeMillis();
			Boolean ok = ftpClient.retrieveFile(new String(name.getBytes("UTF-8"),"ISO-8859-1"), fos);
			if(ok){
				//下载成功
				long times = System.currentTimeMillis() - now;
				System.out.println(String.format("<<<下载成功：大小：%s,上传时间：%d秒", formatSize(ftpFiles[i].getSize()),times/1000));
				c++;
			} else{
				System.out.println("<<<下载失败");
			}
		}
		catch(IOException e){
			System.err.println("<<<下载失败");
			e.printStackTrace();
		}
		finally{
			try{
				if(fos!=null)
				            fos.close();
				close(ftpClient);
			}
			catch(Exception e){
			}
		}
	}
	return c;
}

private static final DecimalFormat DF = new DecimalFormat("#.##");
  /**
   * 格式化文件大小（B，KB，MB，GB）
   * @param size
   * @return
   */
  private String formatSize(long size){
    if(size<1024){
      return size + " B";
    }else if(size<1024*1024){
      return size/1024 + " KB";
    }else if(size<1024*1024*1024){
      return (size/(1024*1024)) + " MB";
    }else{
      double gb = size/(1024*1024*1024);
      return DF.format(gb)+" GB";
    }
  }

public static void main(String args[]){
    FTPTest ftp = new FTPTest("192.168.1.10",21,null,null,"/temp/2016/12");
    ftp.upload("newFile.rar", "D:/ftp/TeamViewerPortable.rar");
    System.out.println("");
    ftp.download("D:/ftp/");
  }

===连接到FTP：192.168.1.10:21
>>>开始上传文件：TeamViewerPortable.rar
>>>上传成功：大小：5 MB,上传时间：3秒
!!!断开FTP连接：192.168.1.10:21

===连接到FTP：192.168.1.10:21
<<<开始下载文件：newFile.rar
<<<下载成功：大小：5 MB,上传时间：4秒
!!!断开FTP连接：192.168.1.10:21