基于FtpClient(JDK1.7)实现Ftp连接

FTP 概述

文件传输协议（FTP）作为网络共享文件的传输协议，在网络应用软件中具有广泛的应用。FTP的目标是提高文件的共享性和可靠高效地传送数据。

在传输文件时，FTP 客户端程序先与服务器建立连接，然后向服务器发送命令。服务器收到命令后给予响应，并执行命令。FTP 协议与操作系统无关，任何操作系统上的程序只要符合 FTP 协议，就可以相互传输数据。

FTP 协议

相比其他协议，如 HTTP 协议，FTP 协议要复杂一些。与一般的 C/S 应用不同点在于一般的C/S 应用程序一般只会建立一个 Socket 连接，这个连接同时处理服务器端和客户端的连接命令和数据传输。而FTP协议中将命令与数据分开传送的方法提高了效率。

FTP 使用 2 个端口，一个数据端口和一个命令端口（也叫做控制端口）。这两个端口一般是21 （命令端口）和 20 （数据端口）。控制 Socket 用来传送命令，数据 Socket 是用于传送数据。每一个 FTP 命令发送之后，FTP 服务器都会返回一个字符串，其中包括一个响应代码和一些说明信息。其中的返回码主要是用于判断命令是否被成功执行了。

基于FtpClient实现的Ftp连接实现原理层也是通过Socket来实现的

以下是示例代码：

package com.test;import java.io.DataInputStream;
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 java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Pattern;import sun.net.ftp.FtpClient;
import sun.net.ftp.FtpProtocolException;/*** Java自带的API对FTP的操作* * 文件名称：FtpUtil.java*/
public final class FtpUtil {private FtpUtil(){}public final static int BUFF_SIZE = 1024;/*** ftp文件上传* @param connectionString ftp协议链接字符串 ftp://用户名:密码@地址:端口/ 或  ftp://地址:端口/* @param localFile 本地文件或文件夹* @param isOver 是否覆盖存在文件* @throws RuntimeException */@SuppressWarnings("restriction")public final static void upload(String connectionString, File localFile, boolean isOver) throws RuntimeException{if(!localFile.exists()){throw new RuntimeException("local file is exists!");}FtpClient ftpClient = connect(connectionString);try {upload(ftpClient, localFile, isOver);}finally {try{ftpClient.close();}catch(Exception ex){throw new RuntimeException(ex);}}}/*** ftp文件上传* @param connectionString ftp协议链接字符串 ftp://用户名:密码@地址:端口/ 或  ftp://地址:端口/* @param remoteFile ftp服务器文件名称* @param fileStream 待写入文件流* @param isOver 是否覆盖存在文件* @throws RuntimeException*/@SuppressWarnings("restriction")public final static void upload(String connectionString, String remoteFile, InputStream fileStream, boolean isOver) throws RuntimeException {FtpClient ftpClient = connect(connectionString);try {if(!"".equals(ftpClient.getStatus(remoteFile)) && !isOver)//是否覆盖文件return;try (OutputStream os = ftpClient.putFileStream(remoteFile); InputStream is = fileStream) {byte[] bytes = new byte[BUFF_SIZE];// 创建一个缓冲区int c;while ((c = is.read(bytes)) > 0) {os.write(bytes, 0, c);}}} catch(Exception ex){throw new RuntimeException("input stream write fail!", ex);}finally {try{ftpClient.close();}catch(Exception ex){throw new RuntimeException(ex);}}}/*** 文件上传* @param ftpClient ftp客户端句柄* @param localFile 本地文件或文件夹* @param isOver 是否覆盖存在文件* @throws RuntimeException*/@SuppressWarnings("restriction")private static void upload(FtpClient ftpClient, File localFile, boolean isOver) throws RuntimeException {if(localFile.isDirectory()){try{try{ftpClient.changeDirectory(localFile.getName());}catch(Exception ex){ftpClient.makeDirectory(localFile.getName());ftpClient.changeDirectory(localFile.getName());}String[] files = localFile.list();File tempFile;for (int i = 0; i < files.length; i++) {        tempFile = new File(localFile.getPath()+"\\"+files[i] );        if(tempFile.isDirectory()){        upload(ftpClient, tempFile, isOver);        ftpClient.changeToParentDirectory();        }else{                      tempFile = new File(localFile.getPath()+"\\"+files[i]);        streamWrite(ftpClient, tempFile, isOver);}                   }        }catch(Exception ex){throw new RuntimeException(ex);}}else{        streamWrite(ftpClient, localFile, isOver);}        } /*** 文件写入到ftp服务器* @param ftpClient ftp客户端句柄* @param localFile 本地文件* @param isOver 是否覆盖存在文件* @throws RuntimeException*/@SuppressWarnings("restriction")private static void streamWrite(FtpClient ftpClient, File localFile, boolean isOver) throws RuntimeException{try{if(!"".equals(ftpClient.getStatus(localFile.getName())) && !isOver)//是否覆盖文件return;try (OutputStream os = ftpClient.putFileStream(localFile.getName());InputStream is = new FileInputStream(localFile)) {byte[] bytes = new byte[BUFF_SIZE];// 创建一个缓冲区int c;while ((c = is.read(bytes)) > 0) {os.write(bytes, 0, c);}}}catch(Exception ex){throw new RuntimeException(ex);}}/** * 从ftp下载文件到本地 *  * @param filename 服务器上的文件名 * @param newfilename 本地生成的文件名 * @return * @throws Exception */  @SuppressWarnings("restriction")public static long downloadFile(FtpClient ftpClient, String filename, String newfilename) {long result = 0;InputStream is = null;FileOutputStream os = null;try {is = ftpClient.getFileStream(filename);java.io.File outfile = new java.io.File(newfilename);os = new FileOutputStream(outfile);byte[] bytes = new byte[is.available()];int c;while ((c = is.read(bytes)) != -1) {os.write(bytes, 0, c);result = result + c;}} catch (IOException | FtpProtocolException e) {e.printStackTrace();} finally {try {if (is != null) {is.close();}if (os != null) {os.close();}} catch (IOException e) {e.printStackTrace();}}return result;}/** * 取得相对于当前连接目录的某个目录下所有文件列表 *  * @param path * @return * @throws FtpProtocolException */  @SuppressWarnings("restriction")public static List<Object> getFileList(FtpClient ftpClient,String path) throws FtpProtocolException{  List<Object> list = new ArrayList<Object>();  DataInputStream dis;  try {  dis = new DataInputStream(ftpClient.nameList( path));  String filename = "";  while((filename = dis.readLine()) != null){  list.add(filename);  }  } catch (IOException e) {  e.printStackTrace();  }  return list;  }  /*** 连接到ftp服务器* @param ip ftp服务器地址* @param port ftp服务器端口* @param user 登陆ftp服务器用户* @param password 登陆ftp服务器用户密码* @param remotePath ftp服务器文件路径* @return FtpClient* @throws RuntimeException*/@SuppressWarnings("restriction")private static FtpClient connect(String ip, int port, String user, String password, String remotePath) throws RuntimeException {FtpClient ftpClient = FtpClient.create();SocketAddress addr = new InetSocketAddress(ip, port);try{ftpClient.connect(addr);ftpClient.login(user, password.toCharArray());ftpClient.setBinaryType();if (remotePath!=null && remotePath.length() != 0) { // 把远程系统上的目录切换到参数path所指定的目录String[] paths=remotePath.split("/");for(String path : paths){if(path.length() == 0)continue;try{ftpClient.changeDirectory(path);}catch(FtpProtocolException ex){ftpClient.makeDirectory(path);ftpClient.changeDirectory(path);}}}return ftpClient;}catch(Exception ex){throw new RuntimeException(ex);}}/*** 连接到ftp服务器* @param connectionString 链接字符串* @return*/@SuppressWarnings("restriction")private static FtpClient connect(String connectionString) throws RuntimeException{Pattern pattern = Pattern.compile("^ftp://(?:\\S+?:\\S+?@)?\\S+?(?:\\d+?)?");if(pattern.matcher(connectionString).find()){String autho = "anonymous", uri = connectionString.substring("ftp://".length()).replace("\\", "/"),user = "anonymous",pwd = "", ip = "", remotePath = "";int sp = uri.indexOf("/"), port = 21;if(sp >= 0){remotePath = uri.substring(sp);uri = uri.substring(0, sp);}sp = uri.lastIndexOf("@");if(sp >= 0){autho = uri.substring(0, sp);uri = ip = uri.substring(sp + 1);}sp = autho.lastIndexOf(":");if(sp >= 0){user = autho.substring(0, sp);pwd  = autho.substring(sp + 1);}sp = uri.lastIndexOf(":");if(sp >= 0){ip = uri.substring(0, sp);port  = Integer.parseInt(uri.substring(sp + 1));}return connect(ip, port, user, pwd, remotePath);}throw new RuntimeException("connectionString is invalid!");}/** * 断开与ftp服务器连接 *  * @throws IOException */ @SuppressWarnings("restriction")public static boolean closeServer(FtpClient ftpClient) {  try {  if (ftpClient != null) {  //ftpClient.closeServer();  ftpClient.close();}  System.out.println("已从服务器断开");  return true;  } catch (IOException e) {  e.printStackTrace();  return false;  }  }  @SuppressWarnings("restriction")public static void main(String[] args) throws FtpProtocolException {FtpClient ftpClient=connect("192.168.10.11", 22, "test_ftp", "test_123", "/test");System.out.println("===="+ftpClient.isPassiveModeEnabled());//upload(ftpClient, new File("E:\\test\\test12.txt"), true);System.out.println("getFileList: "+getFileList(ftpClient, "/test").get(0));long ll=downloadFile(ftpClient, "/test/test.txt", "E:\\test\\test.txt");System.out.println("long : "+ll);closeServer(ftpClient);}
}

参考自 http://blog.csdn.net/wochunyang/article/details/53332557